an introduction to boundary layer meteorology -回复
boundary layer
How Does a Boundary Layer Help Engineers!
• This means that instead of solving for the whole Navier Stokes equation set for the full flow, we can approximate a solution by solving for the boundary layer where the viscous effects are felt. • Thus, in order to calculate skin friction and aerodynamic heating at the surface, you only have to account for friction and thermal conduction within the thin boundary layer. Hence; you wont need to analyze the large flow outside the boundary layer
Properties of Boundary Layers
• The external flow reacts to the edge of the boundary layer just as it would to the physical surface of an object. So the boundary layer gives any object an "effective" shape which is usually slightly different from the physical shape. (Hence, the displacement thickness)
Boundary layer mesh generation for viscous flow simulations
INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERINGInt.J.Numer.Meth.Engng2000;49:193–218Boundary layer mesh generation forviscous ow simulationsRao V.Garimella∗;†and Mark S.Shephard‡Scientiÿc Computation Research Center;Rensselaer Polytechnic Institute;Troy NY12180;U.S.A.SUMMARYViscous ow problems exhibit boundary layers and free shear layers in which the solution gradients,normal and tangential to the ow,di er by orders of magnitude.The generalized advancing layers method is presented here as a method of generating meshes suitable for capturing such ows.The method includes several new technical advances allowing it to mesh complex geometric domains that cannot be handled by other techniques.It is currently being used for simulations in the automotive industry.Copyright?2000John Wiley&Sons,Ltd.KEY WORDS:anisotropic mesh generation;boundary layer meshes;viscous ow simulations1.INTRODUCTIONMany physical problems exhibit relatively strong gradients in certain local directions compared to the other directions.Some examples of such situations are thermal and uid boundary layers, and non-linear solutions in domains with very thin sections.A minimum element size along these directions is necessary to capture the solution in these regions.Anisotropic meshes with small ele-ment sizes in the directions of strong gradients and large sizes along the others leads to signiÿcant savings in mesh size and solution costs.High Reynolds number uid ow simulations have boundary layers at the wall and also free shear layers not attached to any model boundary.The relative rates at which the solution vari-ables change in boundary and shear layers,normal and tangential to the ow,di er by orders of magnitude in such e of properly aligned anisotropic meshes in these cases is essential.A generalization of the advancing layers method[1–4]is presented here for generating boundary layer meshes.The method is designed to e ciently and reliably generate good quality anisotropic tetrahedra near the boundary layer surfaces for arbitrarily complex non-manifold domains starting from a surface mesh.The method has several improvements over the previous advancing layers techniques.It is demonstrated that the common strategy of in ating the surface mesh as is to∗Correspondence to:R.V.Garimella,Los Alamos National Laboratory,EES-5,MS C306,Los Alamos,NM87545, U.S.A.†E-mail:raogarimella@‡E-mail:shephard@Received15April1999 Copyright?2000John Wiley&Sons,Ltd.Revised4August1999194R.V.GARIMELLA AND M.S.SHEPHARDform the boundary layer leads to invalid meshes for some non-manifold models and poor quality elements at sharp corners in2-manifold models.Various procedures are described to make the boundary layer elements valid and to ensure that the mesh is not self-intersecting.The improve-ments incorporated into the method has enabled it to be used successfully to generate boundary layer meshes for geometrically complex industrial models.The rest of this paper is organized in the following manner.A review of the previous e orts in anisotropic mesh generation is presented in Section2.Deÿnitions and notations are described in Section3.Section4presents an overview of the generalized advancing layers method used here.Section5discusses point placement for boundary layer meshing of arbitrarily complex non-manifold geometric domains.Section6describes techniques to ensure that the boundary layer elements generated will be valid while the creation of boundary layer elements is presented in Section7.Section8discusses the method used to guarantee that the boundary layer mesh is not self-intersecting.2.REVIEW OF MESH GENERATION FOR VISCOUS FLOW SIMULATIONS Direct generation of unstructured anisotropic meshes has been attempted with both Delaunay [5–8]and advancing front methods[9–11].The Delaunay criterion itself will always deÿne as isotropic a mesh as possible for a given set of points within the space in which they are deÿned. Therefore,e orts on generating anisotropic meshes using the Delaunay method have focused on meshing in a transformed space using metrics which will yield an anisotropic mesh in the real space.Mavripilis[12]presented a method for anisotropic adaptation of triangular meshes constructing a metric based on two independent stretch vectors at each ing this metric the local space is mapped to a control surface in a transformed higher dimension space in which a Delaunay triangulation is performed.Vallet et al.[13]have proposed a similar idea for the initial mesh generation process as well as adaptation.George et al.[5;6;14]have generalized the ideas of generating anisotropic mesh generation by the Delaunay method using metric speciÿcations.Also,the metrics are modiÿed near viscous walls to keep the mesh as orthogonal to the wall as possible and maintain a certain minimum distance of theÿrst node from the wall.Hassan et al.[15]have used a modiÿed advancing front method to generate anisotropic meshes where a layer of elements is generated from a front using isotropic criteria and compressed to the desired thickness.While this method worked well in2D,it is prone to problems in3D[16]. Hassan et al.[16]have also devised a variation of the advancing front method for boundary layer mesh generation.In this method,the standard advancing front procedure is adapted to place new vertices at the o sets required to generate anisotropic elements.Marcum and Weatherill[17]have described an approach for unstructured grid generation for viscous ows using iterative point insertion followed by local reconnection subject to a quality criteria.The point distribution for the anisotropic mesh is generated along‘normals’to surfaces according to user speciÿcations or error estimates.The most interesting aspect of this work is that they account for sharp‘discontinuities’at edges and vertices and generate points along additional directions in such cases.Most of the work in generating meshes for viscous ow simulations has been in the direction of generating an anisotropic mesh next to surfaces where a boundary layer is expected and then Copyright?2000John Wiley&Sons,Ltd.Int.J.Numer.Meth.Engng2000;49:193–218BOUNDARY LAYER MESH GENERATION195ÿlling the rest of the domain by an isotropic mesh generator.The advancing layers method starts from a triangulation of the surfaces on which the boundary layer mesh must be grown.From each surface node a direction is picked for placing the nodes of the anisotropic mesh.These nodes are connected to form layers of prisms(if necessary,subdivided into tetrahedra)on top of each surface triangle.L o hner[3]described one of the early e orts for combining layers of anisotropic tetrahedronized prisms grown on some model boundaries with an unstructured isotropic mesh generated by an advancing front method in the rest of the domain.The procedure detects poorly shaped,improperly sized and intersecting elements,and deletes them.A recent paper by L o hner[18]advocates the use of anisotropic reÿnement of an isotropic mesh using the Delaunay criterion to generate boundary layer meshes.Kallinderis et al.[2;19]have developed a hybrid prismatic=tetrahedral mesh generator by en-closing the body around which the ow is to be simulated with layers of prisms and thenÿlling the rest of the domain using a combination of octree and advancing front methods.The procedure incorporates an algorithm to ensure that the interior nodes of the prisms are‘visible’from all the relevant faces of the previous layer[2].Included in this method is a procedure to automatically recede and smoothly grade layers in conÿned regions of the model based on ray tracing methods [19].Sharov and Nakahashi[20]have described a similar method with some modiÿcations for generating better elements and for generating all tetrahedra.Pirzadeh[4]describes a similar approach called the advancing layers method(ALM)for the generation of anisotropic meshes for viscous ow calculations.The signiÿcant features of this work are:(1)introduction of prism templates,(2)a non-iterative procedure for obtaining valid diagonals for the prisms,(3)an iterative procedure for obtaining valid directions for placement of points and(4)a procedure for avoiding interference between layers.Connell and Braaten[1]described an implementation of the advancing layers procedure with enhancements to deal with general domains.Their work discusses many of the fundamental issues with mesh generation for viscous ow simulations using the advancing layers methods.The paper details an algorithm to ensure that all prisms have a valid set of diagonals.Also,discussed is a technique,for grading the boundary layer mesh to avoid exposing highly stretched faces to the isotropic mesh generator when elements are deleted.They also discuss the interference of layers, varying thickness boundary layers and resolution of wakes.The advancing layers algorithms reviewed above posses the following complexities:1.They cannot deal with general non-manifold situations.2.They do not account for general interactions of the boundary layer mesh with adjacentsurfaces.3.They may produce poor-quality meshes in the presence of sharp discontinuities in the surfacenormals.4.They do not su ciently address the issue of interaction of anisotropic faces of the boundarylayer mesh with the isotropic mesh.5.They do not provide assurance algorithm for non-interference of boundary layers.The research described herein is a generalization of the advancing layers method mentioned above combined with an isotropic mesh generator based on a combination of advancing front and Delaunay methods[21;33].It addresses many of the issues that arise for complex non-manifold models enabling it to reliably mesh these domains.Copyright?2000John Wiley&Sons,Ltd.Int.J.Numer.Meth.Engng2000;49:193–218196R.V.GARIMELLA AND M.S.SHEPHARD3.DEFINITIONS AND NOTATIONS3.1.Geometric model deÿnitions and conceptsGeometric models may be 2-manifold or non-manifold .Informally,non-manifold models are gen-eral combinations of solids,surfaces and wires [22;23].Geometric model entities are denoted here by G d i ,representing the i th geometric model entity of order d (d =0;1;2;3for vertices,edges,faces and regions,respectively).The data structure used to represent the model in this work is based on the radial edge data structure [23]which presents the idea of uses to represent how topological entities are used by others in a non-manifold model.Every face in the model has two face uses,one on each side of the face.An edge carries as many pairs of uses as there are pairs of face uses coming into it.A vertex carries as many uses as there are edge uses coming into it.The radial edge data structure is more detailed than the minimum amount of information required to represent non-manifold models.The representation can be reduced by fusing edge uses together to form a single ‘edge use’connected to two face uses.Similarly,vertex uses are condensed so that the minimum number of uses are present at any vertex.Such a data structure is referred to as the minimal use data structure [24].3.2.Mesh deÿnitions and conceptsThe representation for the mesh [25–27]used here consists of mesh vertices,edges,faces and regions (and if necessary,their uses).Mesh entities are denoted by M d i ,referring to the i th mesh entity of order d (d =0;1;2;3for vertices,edges,faces and regions,respectively).Each entity in the mesh has a unique classiÿcation with respect to the model.Deÿnition 3.1.Classiÿcation is the unique association of a mesh entity,M d i i ,to a geometricmodel entity,G d j j (d i 6d j )to indicate that M d i i forms part or all of the discretization of G d j j butnot its boundary.The classiÿcation operator is denoted by @and M d i i @G d j j is used to denote theclassiÿcation of M d i i on G dj j .Deÿnition 3.2.A mesh manifold is a set of mesh face uses around a vertex,connected by edge uses,that locally separate the three-dimensional space into two halves.Some examples of mesh face use manifolds are shown in Figure 1.In Figure 1(a),meshmanifolds for a mesh vertex classiÿed on a model face,M 0v @G 20,are shown.In Figure 1(b),mesh manifolds are shown for two vertices in a non-manifold model.In the ÿgure,G 21is an embedded face §making edge contact with two model faces G 20and G 22.The local topology atM 0a is non-manifold and two mesh manifolds exist at the vertex with respect to just one side of the model faces G 20and G 22.At M 0b ,only one mesh manifold exists in the model region under consideration.The concept of mesh manifolds is used to conceptually reduce a complex non-manifold boundary to a set of topologically simple 2-manifold boundaries.§Embedded face –face with the same model region on both sides.Copyright ?2000John Wiley &Sons,Ltd.Int.J.Numer.Meth.Engng 2000;49:193–218BOUNDARY LAYER MESH GENERATION197Figure1.Examples of mesh face use manifolds.4.OVERVIEW OF GENERALIZED ADVANCING LAYERS METHODThe boundary layer meshing approach described here employs the advancing layers approach as its basis and generalizes it for meshing arbitrarily complex non-manifold geometric domains with good quality anisotropic elements near the surface.The technique is therefore referred to as the generalized advancing layers method.Like the advancing layers method,the procedure takes an input surface mesh,grows the anisotropic boundary layer mesh on it and then hands it over to the isotropic mesher toÿnish meshing the domain.Nodes of the boundary layer mesh are placed on curves(called growth curves)originating from surface mesh nodes.These boundary layer nodes are connected to form the anisotropic elements of the boundary layer mesh.However,unlike other methods,the generalized advancing layers method allows multiple growth curves(i.e.multiple sets of boundary layer nodes)to emanate from each surface node.Therefore, the anisotropic mesh is not constrained to be an in ation of the surface triangles into triangular prisms and their tetrahedronization.The exibility of introducing multiple growth curves eliminates the restriction that boundary layer prisms sharing a surface mesh edge or vertex must be joined along their sides.The procedure incorporates techniques toÿll the gaps between prisms caused by multiple growth curves.This is important since failure to do so will expose the highly anisotropic faces to the isotropic mesher.The basic steps of the generalized advancing layers method are as follows(refer Figure2):1.Growth curves areÿrst determined at mesh vertices classiÿed on model vertices.2.If any of these growth curves lie partly or fully on a model edge,the boundary layer entities(mesh vertices and edges)classiÿed on the model edges are created.3.Boundary layer mesh entities classiÿed on model edges are incorporated into the model edgediscretization.4.Growth curves are determined at mesh vertices classiÿed on model edges(Figure2(b)).5.The growth curves that lie on model boundaries are smoothed,shrunk or pruned to avoidcrossover and self-intersection.6.Growth curves on the model boundary are combined to form three types of abstract boundarylayer constructs—quads,transitions and blends.These constructs are triangulated resulting in boundary layer triangles classiÿed on model faces.Copyright?2000John Wiley&Sons,Ltd.Int.J.Numer.Meth.Engng2000;49:193–218198R.V.GARIMELLA AND M.S.SHEPHARDFigure2.Steps of boundary layer meshing:(a)surface mesh;(b)growth curves on model vertices and model edges;(c)boundary retriangulation;(d)growth curves on model faces;(e)prism creation;(f)blend creation;(g)ÿxing self-intersection;(h)meshing remaining portion of domain by an isotropic mesher.7.Boundary layer triangles lying on model faces are incorporated into the surface triangulation(Figure2(c)).8.Growth curves are determined at mesh vertices classiÿed on model faces(Figure2(d)).9.These growth curves are smoothed,shrunk and pruned to ensure creation of valid elements.10.Growth curves are connected up in the interior to form three more types of abstract boundarylayer constructs—prisms,blends and transition elements(Figure2(e)and2(f)).The com-ponent tetrahedra of these abstractions are directly created to form the solid elements of the boundary layer mesh.11.The inner boundary of the boundary layer mesh is checked for self-intersection so as toprovide valid input to the isotropic mesher.Self intersections areÿxed by local shrinking of the layers locally and then by deletion of elements,if necessary(Figure2(g)).12.The rest of the domain is meshed by the isotropic mesher(Figure2(h)).5.GROWTH CURVES5.1.IntroductionPoints in the boundary layer mesh are placed along boundary and interior growth curves while respecting user-requested layer sizes.All nodes of an interior growth curve except theÿrst are classiÿed in a region of the model.Interior growth curves are straight lines with present capabilities of the mesher.All nodes of a boundary growth curve are classiÿed on the boundary of the model. Boundary growth curves may take an arbitrary shape deÿned by the surface that the nodes of the growth curves are classiÿed on.Copyright?2000John Wiley&Sons,Ltd.Int.J.Numer.Meth.Engng2000;49:193–218BOUNDARY LAYER MESH GENERATION199Figure3.Need for multiple growth curves at non-manifold boundaries:(a)single growth curve along G11;(b)two growth curves along G11.The quality of tetrahedra resulting from prisms in the advancing layers method is heavily in u-enced by the deviation of the sides of the prism from the normal direction to the base triangle. Therefore,nodes of growth curves growing from mesh vertices classiÿed on model edges and vertices are allowed to lie on the boundary if the normal direction of the growth curve is close to the adjacent model surfaces and if the quality of the elements will be good with the nodes on the boundary.The generalized advancing layers method permits multiple growth curves to originate into a single region from any mesh vertex classiÿed on the model boundary.The number of growth curves at any mesh vertex with respect to a model face use depends on the local model topology and geometry.The topological requirement for multiple growth curves at a mesh vertex with respect to a single face use arises at some non-manifold boundaries.At these boundaries,multiple growth curves are necessary for generating a valid mesh.Axiom5.1.The minimum number of growth curves at any boundary mesh vertex required to produce a topologically valid mesh is equal to the number of mesh manifolds at the vertex that include at least one mesh face use classiÿed on a model face with a boundary layer.The above assertion can be easily demonstrated by the example shown in Figures3(a)and3(b).Here,the embedded face G21is incident on vertex G01along with two other faces,G22and G23.Itis assumed that a boundary layer mesh is being grown on G22and on both sides of G21.It can be seen from Figure3(a)that use of only one growth curve at M0i@G01and M0i@G11will lead to intersection of some quads with G11or penetration of G21.Two growth curves at the vertex,one for each mesh manifolds at the vertex is the minimum acceptable number.Also,the nodes of each of these growth curves must lie within the respective mesh manifold(Figure3(b)).Similarly,in 3D,interior edges may penetrate model faces if the minimum number of growth curves are not present at each vertex.At some mesh vertices,multiple growth curves may become necessary due to the geometry of the model faces and the coarseness of their discretization.This is because creation of valid prisms requires that the nodes of a growth curve at any mesh vertex be‘visible’from any mesh face connected to the mesh vertex.Nodal visibility ensures that an element formed by connecting the mesh face to the node has positive volume.If the surface discretization is very coarse or theCopyright?2000John Wiley&Sons,Ltd.Int.J.Numer.Meth.Engng2000;49:193–218200R.V.GARIMELLA AND M.S.SHEPHARDFigure4.Mesh face use subsets in mesh manifolds:(a)all mesh faces share common growth curve;(b)two convex edges,shown by curved double-headed arrows,in mesh manifold;(c)three convex edges in mesh manifold;(d)only one convex edge in mesh manifold which is subdivided into two subsets. model geometry itself changes enough,the normals of the mesh faces may vary so much that it may not be possible toÿnd a valid common node that is visible from all the faces(even with methods described in References[4;28]).Such impossible situations are the limit of the case where the growth curve deviates greatly from the mesh face normal leading to large dihedral angles in elements.Therefore,in general,it is desirable to have multiple growth curves at mesh vertices where the normals of the connected mesh faces change too much.In keeping with the necessity of creating a valid mesh and desirability of creating well-shaped prisms,mesh manifolds areÿrst found at each vertex and these are then divided up into subsets of mesh face uses.Each of these subsets of mesh face uses then share a common growth curve to be used in their prisms.The procedures toÿnd these subsets works with face=side pairs in the mesh instead of requiring face uses to be represented.The determination of subsets of mesh face uses in a mesh manifold sharing a common growth curve is based on the dihedral angle between pairs of mesh face uses.Figure4shows some examples of mesh face use subsets.In Figure4(a),the mesh face uses(shown shaded)form a single subset sharing one growth curve.In Figures4(b)and4(c)some pairs of mesh face uses have a large dihedral angle between them and therefore they are split up into multiple face use sets.In Figure4(d),the mesh face uses are split up into two subsets since there is only one pair of face uses with a large dihedral angle and using only one growth curve for this manifold will result in at elements.5.2.Calculation of growth curvesGrowth curves from mesh vertices classiÿed on model vertices and model edges areÿrst attempted to be grown as boundary growth curves.In doing so,the growth curves must respect topological Copyright?2000John Wiley&Sons,Ltd.Int.J.Numer.Meth.Engng2000;49:193–218BOUNDARY LAYER MESH GENERATION201Figure5.Methods of specifying boundary layers:(a)geometric variation of layer thickness;(b)exponential variation of layer thickness;(c)adaptively varying boundary layer thickness;(d)prescribed variation in boundary layer thickness;(e)prescribed variation of boundary layer thickness and number of layers. compatibility of the mesh with the model and estimated geometric validity of mesh.If creating a boundary growth curve violates any of these requirements,the growth curve is grown into the interior.In computing growth curves,it is assumed that all nodes of the growth curves except the ÿrst have a single classiÿcation on the lowest order model entity possible.For example,when constructing a growth curve from a mesh vertex classiÿed on a model vertex,the lowest order model entity that can carry the growth curve is a connected model edge.Since model edges and faces may be curved,a straight line approximation of the growth curve(obtained from an average normal of the given mesh face uses)is used toÿnd locations on the model entity close to the initial positions of the nodes.An extensive set of checks is performed to ensure that the computed growth curve satisÿes validity and quality requirements of the mesh.Checks are performed to ensure that future con-nections(mesh edges and faces)between the growth curve and any adjacent boundary growth curves will not violate topological compatibility.Also,dihedral angles of future elements resulting from the growth curve are estimated to ensure element quality.If two growth curves from a mesh vertex in a non-manifold model lie on the same model face,they are checked to see if they are Copyright?2000John Wiley&Sons,Ltd.Int.J.Numer.Meth.Engng2000;49:193–218202R.V.GARIMELLA AND M.S.SHEPHARDcoincident and merged.If not,they are checked to ensure that boundary layer quads to be formed with them will not intersect each other.In case of intersection,the growth curve is not created and the other growth curve is used instead.5.3.Node spacing along the growth curvesNode spacing for growth curves may be speciÿed in one of three ways—geometric,exponential or adaptive.In the geometric method,theÿrst layer thickness,the number of layers and the total thickness of the boundary layer mesh are ing this,the thickness of the individual layers is calculated to grow by geometric progression(Figure5(a)).For exponential growth,only theÿrst layer thickness and number of layers is speciÿed for calculation of the node spacing(Figure5(b)).The growth of the layer thicknesses is exponential. In the adaptive method of boundary layer thickness speciÿcation,theÿrst layer thickness t0 and the number of layers,n,are speciÿed.The growth of the boundary layer thickness is still geometric but the layer thickness growth factor r is calculated to ensure a smooth gradation of the boundary layer mesh into the isotropic mesh(Figure5(c)).This is done by assuming the last layer thickness to be times the isotropic mesh size,0:5¡ ¡1:0.The attribute speciÿcation system used for prescribing boundary layer mesh parameters allows spatial variation of all the variables,t0,T and n while maintaining the geometric growth rate of layer thicknesses(Figure5(d)).Figure5(e)shows the boundary layers when the boundary layer thickness and the number of layers both vary on a model entity.6.ENSURING ELEMENT VALIDITYInvalidity of elements in the generalized advancing layers method occurs due to invisibility of growth curve nodes from a mesh face and due to crossover of growth curves(Figure6(a)).The former is dealt with during growth curve creation and the latter is dealt with after the creation of all growth curves.Growth curve crossover is addressed here by smoothing,shrinking and pruning applied in that order.In the smoothing step(Figure6(b)),a weighted Laplacian smoothing procedure is applied to growth curves to eliminate crossover.It is the preferred method of eliminating crossover since it respects the original spacing of nodes along the growth curves.Although smoothing distorts previously well shaped elements,it also corrects crossover in many cases and evens out shape and size variations in the boundary layer mesh.Smoothing of interior growth curves is done by reorienting each growth curve to the average of its adjacent growth curves.Smoothing of boundary growth curves is done by a modiÿed procedure that accounts for their general shape.In this procedure,straight line approximations of the growth curve and its adjacent boundary growth curves are used for computing a smoothed direction and closest point searches done to locate the nodes of the growth curve onto the model boundary.Multiple passes of smoothing are used over each entity and over all the entities.The shrinking procedure is based on the principle that crossover often occurs because the bound-ary layer is too thick relative to the curvature of the model face or the acuteness of the angle between model=mesh faces.Therefore,the shrinking process locally reduces the thickness of the boundary layers if it will make the a ected elements valid(Figure6(c)[i]).This is accomplished by progressively reducing the node spacing of the boundary and interior growth curves which are Copyright?2000John Wiley&Sons,Ltd.Int.J.Numer.Meth.Engng2000;49:193–218。
Chapter2.PlanetaryBoundary
• we live in it • it is where and how most of the solar heating gets into the atmosphere • it is complicated due to the processes of the ground (boundary) • boundary layer is very turbulent • others …
Main references: Stull, R. B., 1988: An Introduction to Boundary Layer Meteorology. Kluwer Academic, 666 pp.
2.1. Planetary boundary layer and its structure
• The virtual potential temperature (it determines the buoyancy) is nearly adiabatic (i.e., constant with height) in the middle portion of the mixed layer (ML), and is super-adiabatic in the surface layer. At the top of the ML there is usually a stable layer to stop the turbulent eddies from rising further. When the layer is very stable so that the temperature increases with height, it is usually called capping inversion. This capping inversion can keep deep convection from developing.
an introduction to boundary layer meteorology
an introduction to boundary layermeteorology篇幅较长，请耐心阅读。
引言：边界层气象学是气象学中一门重要的分支领域，研究大气中接触地球表面的那一层空气，称为边界层。
边界层的特性对气象的各个方面都有着重要影响，如天气现象、能量交换和大气环流等。
本文将详细介绍边界层气象学的基本概念、形成机制、结构特征以及对气象现象的影响。
一、基本概念边界层是指大气中与地表直接接触的那一层空气，其厚度通常在几百米到几千米之间。
它是大气的底层，也是大气与地表之间交换能量、质量和动量的重要界面。
边界层气象学研究的是这一层空气的性质、运动和动力学过程。
二、形成机制边界层的形成主要受地表特性和大气的垂直运动的影响。
大气的垂直运动包括对流、辐射冷却和湍流。
而地表特性指的是地形、土壤类型和植被等。
这些因素共同作用，导致边界层的形成与发展。
1. 对流运动当地表受到太阳辐射而变暖时，空气会受热膨胀，产生上升的气流，称为热对流。
这种上升气流在边界层内不断形成，导致边界层内形成对流的垂直运动。
2. 辐射冷却夜间，地表辐射能量会减少，导致地表变冷。
此时，边界层中的空气也会受到冷却，从而形成下沉气流。
3. 湍流地表和大气之间存在着湍流运动。
湍流是指流体中涡旋运动的不规则运动形式，它使得边界层中的空气不断混合、扩散和交换。
三、结构特征边界层的结构特征包括温度、风速和湍流等方面的变化规律。
1. 温度边界层中的温度变化主要表现在垂直方向，通常呈现降温的趋势。
接近地表的地方，温度变化比较显著，趋于稳定。
而在边界层顶端，温度变化相对较小。
2. 风速边界层内的风速和风向变化较大。
对流运动导致的上升气流和下沉气流使得风速具有垂直剖面变化的特点。
接近地表的地方，风速较小，但上升至较高高度后，风速会逐渐增大。
3. 湍流边界层中湍流的运动非常活跃。
湍流运动混合了不同层次的空气，使得水平和垂直上的质量、能量和动量交换得以实现。
boundary-layer
Boundary Layer Theory
Professor Ugur GUVEN Aerospace Engineer Spacecraft Propulsion Specialist
1
Boundary Layer Definition
• Boundary Layer is the thin boundary region between the flow and the solid surface, where the flow is retarded due to friction between the solid body and the fluid flow.
15
Properties of the Boundary Layer
• Hence since Prandtl number is 0.71 for air at standard conditions, the thermal boundary layer is thicker then the velocity boundary Layer. (Remember Prandtl number is a function of temperature).
Boundary-Layer Separation
第八章 边界层理论剖析
The last chapter introduces Navier-Stokes equation and Reynolds equation, the differential continuity and these two equations form basic differential equation which find the solution of viscosity fluid dynamics. As for they are nonlinear second-order partial differential equations, Reynolds equation is not still be closed, usually we can not obtain the accuracy solution, people turn to seek approximate solution.
Chapter 8 Exercises
3
第八章 边界层理论
§8–1 引言 §8–2 边界层的基本概念 §8–3 边界层的运动微分方程式 §8–4 边界层中的各种厚度 §8–5 边界层的动量方程式和摩擦切应力 §8–6 光滑平板上的层流边界层 第八章 习题
4
Chapter 8 Boundary Layer Theory
has variable velocity du dy is limited to the thinnest layer near the
fixed boundary, which is called boundary layer.
The flow thickness which the velocity increase from 0 to 0.99 U 0
3GPP TS 36.331 V13.2.0 (2016-06)
3GPP TS 36.331 V13.2.0 (2016-06)Technical Specification3rd Generation Partnership Project;Technical Specification Group Radio Access Network;Evolved Universal Terrestrial Radio Access (E-UTRA);Radio Resource Control (RRC);Protocol specification(Release 13)The present document has been developed within the 3rd Generation Partnership Project (3GPP TM) and may be further elaborated for the purposes of 3GPP. The present document has not been subject to any approval process by the 3GPP Organizational Partners and shall not be implemented.This Specification is provided for future development work within 3GPP only. The Organizational Partners accept no liability for any use of this Specification. Specifications and reports for implementation of the 3GPP TM system should be obtained via the 3GPP Organizational Partners' Publications Offices.KeywordsUMTS, radio3GPPPostal address3GPP support office address650 Route des Lucioles - Sophia AntipolisValbonne - FRANCETel.: +33 4 92 94 42 00 Fax: +33 4 93 65 47 16InternetCopyright NotificationNo part may be reproduced except as authorized by written permission.The copyright and the foregoing restriction extend to reproduction in all media.© 2016, 3GPP Organizational Partners (ARIB, ATIS, CCSA, ETSI, TSDSI, TTA, TTC).All rights reserved.UMTS™ is a Trade Mark of ETSI registered for the benefit of its members3GPP™ is a Trade Mark of ETSI registered for the benefit of its Members and of the 3GPP Organizational PartnersLTE™ is a Trade Mark of ETSI currently being registered for the benefit of its Members and of the 3GPP Organizational Partners GSM® and the GSM logo are registered and owned by the GSM AssociationBluetooth® is a Trade Mark of the Bluetooth SIG registered for the benefit of its membersContentsForeword (18)1Scope (19)2References (19)3Definitions, symbols and abbreviations (22)3.1Definitions (22)3.2Abbreviations (24)4General (27)4.1Introduction (27)4.2Architecture (28)4.2.1UE states and state transitions including inter RAT (28)4.2.2Signalling radio bearers (29)4.3Services (30)4.3.1Services provided to upper layers (30)4.3.2Services expected from lower layers (30)4.4Functions (30)5Procedures (32)5.1General (32)5.1.1Introduction (32)5.1.2General requirements (32)5.2System information (33)5.2.1Introduction (33)5.2.1.1General (33)5.2.1.2Scheduling (34)5.2.1.2a Scheduling for NB-IoT (34)5.2.1.3System information validity and notification of changes (35)5.2.1.4Indication of ETWS notification (36)5.2.1.5Indication of CMAS notification (37)5.2.1.6Notification of EAB parameters change (37)5.2.1.7Access Barring parameters change in NB-IoT (37)5.2.2System information acquisition (38)5.2.2.1General (38)5.2.2.2Initiation (38)5.2.2.3System information required by the UE (38)5.2.2.4System information acquisition by the UE (39)5.2.2.5Essential system information missing (42)5.2.2.6Actions upon reception of the MasterInformationBlock message (42)5.2.2.7Actions upon reception of the SystemInformationBlockType1 message (42)5.2.2.8Actions upon reception of SystemInformation messages (44)5.2.2.9Actions upon reception of SystemInformationBlockType2 (44)5.2.2.10Actions upon reception of SystemInformationBlockType3 (45)5.2.2.11Actions upon reception of SystemInformationBlockType4 (45)5.2.2.12Actions upon reception of SystemInformationBlockType5 (45)5.2.2.13Actions upon reception of SystemInformationBlockType6 (45)5.2.2.14Actions upon reception of SystemInformationBlockType7 (45)5.2.2.15Actions upon reception of SystemInformationBlockType8 (45)5.2.2.16Actions upon reception of SystemInformationBlockType9 (46)5.2.2.17Actions upon reception of SystemInformationBlockType10 (46)5.2.2.18Actions upon reception of SystemInformationBlockType11 (46)5.2.2.19Actions upon reception of SystemInformationBlockType12 (47)5.2.2.20Actions upon reception of SystemInformationBlockType13 (48)5.2.2.21Actions upon reception of SystemInformationBlockType14 (48)5.2.2.22Actions upon reception of SystemInformationBlockType15 (48)5.2.2.23Actions upon reception of SystemInformationBlockType16 (48)5.2.2.24Actions upon reception of SystemInformationBlockType17 (48)5.2.2.25Actions upon reception of SystemInformationBlockType18 (48)5.2.2.26Actions upon reception of SystemInformationBlockType19 (49)5.2.3Acquisition of an SI message (49)5.2.3a Acquisition of an SI message by BL UE or UE in CE or a NB-IoT UE (50)5.3Connection control (50)5.3.1Introduction (50)5.3.1.1RRC connection control (50)5.3.1.2Security (52)5.3.1.2a RN security (53)5.3.1.3Connected mode mobility (53)5.3.1.4Connection control in NB-IoT (54)5.3.2Paging (55)5.3.2.1General (55)5.3.2.2Initiation (55)5.3.2.3Reception of the Paging message by the UE (55)5.3.3RRC connection establishment (56)5.3.3.1General (56)5.3.3.1a Conditions for establishing RRC Connection for sidelink communication/ discovery (58)5.3.3.2Initiation (59)5.3.3.3Actions related to transmission of RRCConnectionRequest message (63)5.3.3.3a Actions related to transmission of RRCConnectionResumeRequest message (64)5.3.3.4Reception of the RRCConnectionSetup by the UE (64)5.3.3.4a Reception of the RRCConnectionResume by the UE (66)5.3.3.5Cell re-selection while T300, T302, T303, T305, T306, or T308 is running (68)5.3.3.6T300 expiry (68)5.3.3.7T302, T303, T305, T306, or T308 expiry or stop (69)5.3.3.8Reception of the RRCConnectionReject by the UE (70)5.3.3.9Abortion of RRC connection establishment (71)5.3.3.10Handling of SSAC related parameters (71)5.3.3.11Access barring check (72)5.3.3.12EAB check (73)5.3.3.13Access barring check for ACDC (73)5.3.3.14Access Barring check for NB-IoT (74)5.3.4Initial security activation (75)5.3.4.1General (75)5.3.4.2Initiation (76)5.3.4.3Reception of the SecurityModeCommand by the UE (76)5.3.5RRC connection reconfiguration (77)5.3.5.1General (77)5.3.5.2Initiation (77)5.3.5.3Reception of an RRCConnectionReconfiguration not including the mobilityControlInfo by theUE (77)5.3.5.4Reception of an RRCConnectionReconfiguration including the mobilityControlInfo by the UE(handover) (79)5.3.5.5Reconfiguration failure (83)5.3.5.6T304 expiry (handover failure) (83)5.3.5.7Void (84)5.3.5.7a T307 expiry (SCG change failure) (84)5.3.5.8Radio Configuration involving full configuration option (84)5.3.6Counter check (86)5.3.6.1General (86)5.3.6.2Initiation (86)5.3.6.3Reception of the CounterCheck message by the UE (86)5.3.7RRC connection re-establishment (87)5.3.7.1General (87)5.3.7.2Initiation (87)5.3.7.3Actions following cell selection while T311 is running (88)5.3.7.4Actions related to transmission of RRCConnectionReestablishmentRequest message (89)5.3.7.5Reception of the RRCConnectionReestablishment by the UE (89)5.3.7.6T311 expiry (91)5.3.7.7T301 expiry or selected cell no longer suitable (91)5.3.7.8Reception of RRCConnectionReestablishmentReject by the UE (91)5.3.8RRC connection release (92)5.3.8.1General (92)5.3.8.2Initiation (92)5.3.8.3Reception of the RRCConnectionRelease by the UE (92)5.3.8.4T320 expiry (93)5.3.9RRC connection release requested by upper layers (93)5.3.9.1General (93)5.3.9.2Initiation (93)5.3.10Radio resource configuration (93)5.3.10.0General (93)5.3.10.1SRB addition/ modification (94)5.3.10.2DRB release (95)5.3.10.3DRB addition/ modification (95)5.3.10.3a1DC specific DRB addition or reconfiguration (96)5.3.10.3a2LWA specific DRB addition or reconfiguration (98)5.3.10.3a3LWIP specific DRB addition or reconfiguration (98)5.3.10.3a SCell release (99)5.3.10.3b SCell addition/ modification (99)5.3.10.3c PSCell addition or modification (99)5.3.10.4MAC main reconfiguration (99)5.3.10.5Semi-persistent scheduling reconfiguration (100)5.3.10.6Physical channel reconfiguration (100)5.3.10.7Radio Link Failure Timers and Constants reconfiguration (101)5.3.10.8Time domain measurement resource restriction for serving cell (101)5.3.10.9Other configuration (102)5.3.10.10SCG reconfiguration (103)5.3.10.11SCG dedicated resource configuration (104)5.3.10.12Reconfiguration SCG or split DRB by drb-ToAddModList (105)5.3.10.13Neighbour cell information reconfiguration (105)5.3.10.14Void (105)5.3.10.15Sidelink dedicated configuration (105)5.3.10.16T370 expiry (106)5.3.11Radio link failure related actions (107)5.3.11.1Detection of physical layer problems in RRC_CONNECTED (107)5.3.11.2Recovery of physical layer problems (107)5.3.11.3Detection of radio link failure (107)5.3.12UE actions upon leaving RRC_CONNECTED (109)5.3.13UE actions upon PUCCH/ SRS release request (110)5.3.14Proximity indication (110)5.3.14.1General (110)5.3.14.2Initiation (111)5.3.14.3Actions related to transmission of ProximityIndication message (111)5.3.15Void (111)5.4Inter-RAT mobility (111)5.4.1Introduction (111)5.4.2Handover to E-UTRA (112)5.4.2.1General (112)5.4.2.2Initiation (112)5.4.2.3Reception of the RRCConnectionReconfiguration by the UE (112)5.4.2.4Reconfiguration failure (114)5.4.2.5T304 expiry (handover to E-UTRA failure) (114)5.4.3Mobility from E-UTRA (114)5.4.3.1General (114)5.4.3.2Initiation (115)5.4.3.3Reception of the MobilityFromEUTRACommand by the UE (115)5.4.3.4Successful completion of the mobility from E-UTRA (116)5.4.3.5Mobility from E-UTRA failure (117)5.4.4Handover from E-UTRA preparation request (CDMA2000) (117)5.4.4.1General (117)5.4.4.2Initiation (118)5.4.4.3Reception of the HandoverFromEUTRAPreparationRequest by the UE (118)5.4.5UL handover preparation transfer (CDMA2000) (118)5.4.5.1General (118)5.4.5.2Initiation (118)5.4.5.3Actions related to transmission of the ULHandoverPreparationTransfer message (119)5.4.5.4Failure to deliver the ULHandoverPreparationTransfer message (119)5.4.6Inter-RAT cell change order to E-UTRAN (119)5.4.6.1General (119)5.4.6.2Initiation (119)5.4.6.3UE fails to complete an inter-RAT cell change order (119)5.5Measurements (120)5.5.1Introduction (120)5.5.2Measurement configuration (121)5.5.2.1General (121)5.5.2.2Measurement identity removal (122)5.5.2.2a Measurement identity autonomous removal (122)5.5.2.3Measurement identity addition/ modification (123)5.5.2.4Measurement object removal (124)5.5.2.5Measurement object addition/ modification (124)5.5.2.6Reporting configuration removal (126)5.5.2.7Reporting configuration addition/ modification (127)5.5.2.8Quantity configuration (127)5.5.2.9Measurement gap configuration (127)5.5.2.10Discovery signals measurement timing configuration (128)5.5.2.11RSSI measurement timing configuration (128)5.5.3Performing measurements (128)5.5.3.1General (128)5.5.3.2Layer 3 filtering (131)5.5.4Measurement report triggering (131)5.5.4.1General (131)5.5.4.2Event A1 (Serving becomes better than threshold) (135)5.5.4.3Event A2 (Serving becomes worse than threshold) (136)5.5.4.4Event A3 (Neighbour becomes offset better than PCell/ PSCell) (136)5.5.4.5Event A4 (Neighbour becomes better than threshold) (137)5.5.4.6Event A5 (PCell/ PSCell becomes worse than threshold1 and neighbour becomes better thanthreshold2) (138)5.5.4.6a Event A6 (Neighbour becomes offset better than SCell) (139)5.5.4.7Event B1 (Inter RAT neighbour becomes better than threshold) (139)5.5.4.8Event B2 (PCell becomes worse than threshold1 and inter RAT neighbour becomes better thanthreshold2) (140)5.5.4.9Event C1 (CSI-RS resource becomes better than threshold) (141)5.5.4.10Event C2 (CSI-RS resource becomes offset better than reference CSI-RS resource) (141)5.5.4.11Event W1 (WLAN becomes better than a threshold) (142)5.5.4.12Event W2 (All WLAN inside WLAN mobility set becomes worse than threshold1 and a WLANoutside WLAN mobility set becomes better than threshold2) (142)5.5.4.13Event W3 (All WLAN inside WLAN mobility set becomes worse than a threshold) (143)5.5.5Measurement reporting (144)5.5.6Measurement related actions (148)5.5.6.1Actions upon handover and re-establishment (148)5.5.6.2Speed dependant scaling of measurement related parameters (149)5.5.7Inter-frequency RSTD measurement indication (149)5.5.7.1General (149)5.5.7.2Initiation (150)5.5.7.3Actions related to transmission of InterFreqRSTDMeasurementIndication message (150)5.6Other (150)5.6.0General (150)5.6.1DL information transfer (151)5.6.1.1General (151)5.6.1.2Initiation (151)5.6.1.3Reception of the DLInformationTransfer by the UE (151)5.6.2UL information transfer (151)5.6.2.1General (151)5.6.2.2Initiation (151)5.6.2.3Actions related to transmission of ULInformationTransfer message (152)5.6.2.4Failure to deliver ULInformationTransfer message (152)5.6.3UE capability transfer (152)5.6.3.1General (152)5.6.3.2Initiation (153)5.6.3.3Reception of the UECapabilityEnquiry by the UE (153)5.6.4CSFB to 1x Parameter transfer (157)5.6.4.1General (157)5.6.4.2Initiation (157)5.6.4.3Actions related to transmission of CSFBParametersRequestCDMA2000 message (157)5.6.4.4Reception of the CSFBParametersResponseCDMA2000 message (157)5.6.5UE Information (158)5.6.5.1General (158)5.6.5.2Initiation (158)5.6.5.3Reception of the UEInformationRequest message (158)5.6.6 Logged Measurement Configuration (159)5.6.6.1General (159)5.6.6.2Initiation (160)5.6.6.3Reception of the LoggedMeasurementConfiguration by the UE (160)5.6.6.4T330 expiry (160)5.6.7 Release of Logged Measurement Configuration (160)5.6.7.1General (160)5.6.7.2Initiation (160)5.6.8 Measurements logging (161)5.6.8.1General (161)5.6.8.2Initiation (161)5.6.9In-device coexistence indication (163)5.6.9.1General (163)5.6.9.2Initiation (164)5.6.9.3Actions related to transmission of InDeviceCoexIndication message (164)5.6.10UE Assistance Information (165)5.6.10.1General (165)5.6.10.2Initiation (166)5.6.10.3Actions related to transmission of UEAssistanceInformation message (166)5.6.11 Mobility history information (166)5.6.11.1General (166)5.6.11.2Initiation (166)5.6.12RAN-assisted WLAN interworking (167)5.6.12.1General (167)5.6.12.2Dedicated WLAN offload configuration (167)5.6.12.3WLAN offload RAN evaluation (167)5.6.12.4T350 expiry or stop (167)5.6.12.5Cell selection/ re-selection while T350 is running (168)5.6.13SCG failure information (168)5.6.13.1General (168)5.6.13.2Initiation (168)5.6.13.3Actions related to transmission of SCGFailureInformation message (168)5.6.14LTE-WLAN Aggregation (169)5.6.14.1Introduction (169)5.6.14.2Reception of LWA configuration (169)5.6.14.3Release of LWA configuration (170)5.6.15WLAN connection management (170)5.6.15.1Introduction (170)5.6.15.2WLAN connection status reporting (170)5.6.15.2.1General (170)5.6.15.2.2Initiation (171)5.6.15.2.3Actions related to transmission of WLANConnectionStatusReport message (171)5.6.15.3T351 Expiry (WLAN connection attempt timeout) (171)5.6.15.4WLAN status monitoring (171)5.6.16RAN controlled LTE-WLAN interworking (172)5.6.16.1General (172)5.6.16.2WLAN traffic steering command (172)5.6.17LTE-WLAN aggregation with IPsec tunnel (173)5.6.17.1General (173)5.7Generic error handling (174)5.7.1General (174)5.7.2ASN.1 violation or encoding error (174)5.7.3Field set to a not comprehended value (174)5.7.4Mandatory field missing (174)5.7.5Not comprehended field (176)5.8MBMS (176)5.8.1Introduction (176)5.8.1.1General (176)5.8.1.2Scheduling (176)5.8.1.3MCCH information validity and notification of changes (176)5.8.2MCCH information acquisition (178)5.8.2.1General (178)5.8.2.2Initiation (178)5.8.2.3MCCH information acquisition by the UE (178)5.8.2.4Actions upon reception of the MBSFNAreaConfiguration message (178)5.8.2.5Actions upon reception of the MBMSCountingRequest message (179)5.8.3MBMS PTM radio bearer configuration (179)5.8.3.1General (179)5.8.3.2Initiation (179)5.8.3.3MRB establishment (179)5.8.3.4MRB release (179)5.8.4MBMS Counting Procedure (179)5.8.4.1General (179)5.8.4.2Initiation (180)5.8.4.3Reception of the MBMSCountingRequest message by the UE (180)5.8.5MBMS interest indication (181)5.8.5.1General (181)5.8.5.2Initiation (181)5.8.5.3Determine MBMS frequencies of interest (182)5.8.5.4Actions related to transmission of MBMSInterestIndication message (183)5.8a SC-PTM (183)5.8a.1Introduction (183)5.8a.1.1General (183)5.8a.1.2SC-MCCH scheduling (183)5.8a.1.3SC-MCCH information validity and notification of changes (183)5.8a.1.4Procedures (184)5.8a.2SC-MCCH information acquisition (184)5.8a.2.1General (184)5.8a.2.2Initiation (184)5.8a.2.3SC-MCCH information acquisition by the UE (184)5.8a.2.4Actions upon reception of the SCPTMConfiguration message (185)5.8a.3SC-PTM radio bearer configuration (185)5.8a.3.1General (185)5.8a.3.2Initiation (185)5.8a.3.3SC-MRB establishment (185)5.8a.3.4SC-MRB release (185)5.9RN procedures (186)5.9.1RN reconfiguration (186)5.9.1.1General (186)5.9.1.2Initiation (186)5.9.1.3Reception of the RNReconfiguration by the RN (186)5.10Sidelink (186)5.10.1Introduction (186)5.10.1a Conditions for sidelink communication operation (187)5.10.2Sidelink UE information (188)5.10.2.1General (188)5.10.2.2Initiation (189)5.10.2.3Actions related to transmission of SidelinkUEInformation message (193)5.10.3Sidelink communication monitoring (195)5.10.6Sidelink discovery announcement (198)5.10.6a Sidelink discovery announcement pool selection (201)5.10.6b Sidelink discovery announcement reference carrier selection (201)5.10.7Sidelink synchronisation information transmission (202)5.10.7.1General (202)5.10.7.2Initiation (203)5.10.7.3Transmission of SLSS (204)5.10.7.4Transmission of MasterInformationBlock-SL message (205)5.10.7.5Void (206)5.10.8Sidelink synchronisation reference (206)5.10.8.1General (206)5.10.8.2Selection and reselection of synchronisation reference UE (SyncRef UE) (206)5.10.9Sidelink common control information (207)5.10.9.1General (207)5.10.9.2Actions related to reception of MasterInformationBlock-SL message (207)5.10.10Sidelink relay UE operation (207)5.10.10.1General (207)5.10.10.2AS-conditions for relay related sidelink communication transmission by sidelink relay UE (207)5.10.10.3AS-conditions for relay PS related sidelink discovery transmission by sidelink relay UE (208)5.10.10.4Sidelink relay UE threshold conditions (208)5.10.11Sidelink remote UE operation (208)5.10.11.1General (208)5.10.11.2AS-conditions for relay related sidelink communication transmission by sidelink remote UE (208)5.10.11.3AS-conditions for relay PS related sidelink discovery transmission by sidelink remote UE (209)5.10.11.4Selection and reselection of sidelink relay UE (209)5.10.11.5Sidelink remote UE threshold conditions (210)6Protocol data units, formats and parameters (tabular & ASN.1) (210)6.1General (210)6.2RRC messages (212)6.2.1General message structure (212)–EUTRA-RRC-Definitions (212)–BCCH-BCH-Message (212)–BCCH-DL-SCH-Message (212)–BCCH-DL-SCH-Message-BR (213)–MCCH-Message (213)–PCCH-Message (213)–DL-CCCH-Message (214)–DL-DCCH-Message (214)–UL-CCCH-Message (214)–UL-DCCH-Message (215)–SC-MCCH-Message (215)6.2.2Message definitions (216)–CounterCheck (216)–CounterCheckResponse (217)–CSFBParametersRequestCDMA2000 (217)–CSFBParametersResponseCDMA2000 (218)–DLInformationTransfer (218)–HandoverFromEUTRAPreparationRequest (CDMA2000) (219)–InDeviceCoexIndication (220)–InterFreqRSTDMeasurementIndication (222)–LoggedMeasurementConfiguration (223)–MasterInformationBlock (225)–MBMSCountingRequest (226)–MBMSCountingResponse (226)–MBMSInterestIndication (227)–MBSFNAreaConfiguration (228)–MeasurementReport (228)–MobilityFromEUTRACommand (229)–Paging (232)–ProximityIndication (233)–RNReconfiguration (234)–RNReconfigurationComplete (234)–RRCConnectionReconfiguration (235)–RRCConnectionReconfigurationComplete (240)–RRCConnectionReestablishment (241)–RRCConnectionReestablishmentComplete (241)–RRCConnectionReestablishmentReject (242)–RRCConnectionReestablishmentRequest (243)–RRCConnectionReject (243)–RRCConnectionRelease (244)–RRCConnectionResume (248)–RRCConnectionResumeComplete (249)–RRCConnectionResumeRequest (250)–RRCConnectionRequest (250)–RRCConnectionSetup (251)–RRCConnectionSetupComplete (252)–SCGFailureInformation (253)–SCPTMConfiguration (254)–SecurityModeCommand (255)–SecurityModeComplete (255)–SecurityModeFailure (256)–SidelinkUEInformation (256)–SystemInformation (258)–SystemInformationBlockType1 (259)–UEAssistanceInformation (264)–UECapabilityEnquiry (265)–UECapabilityInformation (266)–UEInformationRequest (267)–UEInformationResponse (267)–ULHandoverPreparationTransfer (CDMA2000) (273)–ULInformationTransfer (274)–WLANConnectionStatusReport (274)6.3RRC information elements (275)6.3.1System information blocks (275)–SystemInformationBlockType2 (275)–SystemInformationBlockType3 (279)–SystemInformationBlockType4 (282)–SystemInformationBlockType5 (283)–SystemInformationBlockType6 (287)–SystemInformationBlockType7 (289)–SystemInformationBlockType8 (290)–SystemInformationBlockType9 (295)–SystemInformationBlockType10 (295)–SystemInformationBlockType11 (296)–SystemInformationBlockType12 (297)–SystemInformationBlockType13 (297)–SystemInformationBlockType14 (298)–SystemInformationBlockType15 (298)–SystemInformationBlockType16 (299)–SystemInformationBlockType17 (300)–SystemInformationBlockType18 (301)–SystemInformationBlockType19 (301)–SystemInformationBlockType20 (304)6.3.2Radio resource control information elements (304)–AntennaInfo (304)–AntennaInfoUL (306)–CQI-ReportConfig (307)–CQI-ReportPeriodicProcExtId (314)–CrossCarrierSchedulingConfig (314)–CSI-IM-Config (315)–CSI-IM-ConfigId (315)–CSI-RS-Config (317)–CSI-RS-ConfigEMIMO (318)–CSI-RS-ConfigNZP (319)–CSI-RS-ConfigNZPId (320)–CSI-RS-ConfigZP (321)–CSI-RS-ConfigZPId (321)–DMRS-Config (321)–DRB-Identity (322)–EPDCCH-Config (322)–EIMTA-MainConfig (324)–LogicalChannelConfig (325)–LWA-Configuration (326)–LWIP-Configuration (326)–RCLWI-Configuration (327)–MAC-MainConfig (327)–P-C-AndCBSR (332)–PDCCH-ConfigSCell (333)–PDCP-Config (334)–PDSCH-Config (337)–PDSCH-RE-MappingQCL-ConfigId (339)–PHICH-Config (339)–PhysicalConfigDedicated (339)–P-Max (344)–PRACH-Config (344)–PresenceAntennaPort1 (346)–PUCCH-Config (347)–PUSCH-Config (351)–RACH-ConfigCommon (355)–RACH-ConfigDedicated (357)–RadioResourceConfigCommon (358)–RadioResourceConfigDedicated (362)–RLC-Config (367)–RLF-TimersAndConstants (369)–RN-SubframeConfig (370)–SchedulingRequestConfig (371)–SoundingRS-UL-Config (372)–SPS-Config (375)–TDD-Config (376)–TimeAlignmentTimer (377)–TPC-PDCCH-Config (377)–TunnelConfigLWIP (378)–UplinkPowerControl (379)–WLAN-Id-List (382)–WLAN-MobilityConfig (382)6.3.3Security control information elements (382)–NextHopChainingCount (382)–SecurityAlgorithmConfig (383)–ShortMAC-I (383)6.3.4Mobility control information elements (383)–AdditionalSpectrumEmission (383)–ARFCN-ValueCDMA2000 (383)–ARFCN-ValueEUTRA (384)–ARFCN-ValueGERAN (384)–ARFCN-ValueUTRA (384)–BandclassCDMA2000 (384)–BandIndicatorGERAN (385)–CarrierFreqCDMA2000 (385)–CarrierFreqGERAN (385)–CellIndexList (387)–CellReselectionPriority (387)–CellSelectionInfoCE (387)–CellReselectionSubPriority (388)–CSFB-RegistrationParam1XRTT (388)–CellGlobalIdEUTRA (389)–CellGlobalIdUTRA (389)–CellGlobalIdGERAN (390)–CellGlobalIdCDMA2000 (390)–CellSelectionInfoNFreq (391)–CSG-Identity (391)–FreqBandIndicator (391)–MobilityControlInfo (391)–MobilityParametersCDMA2000 (1xRTT) (393)–MobilityStateParameters (394)–MultiBandInfoList (394)–NS-PmaxList (394)–PhysCellId (395)–PhysCellIdRange (395)–PhysCellIdRangeUTRA-FDDList (395)–PhysCellIdCDMA2000 (396)–PhysCellIdGERAN (396)–PhysCellIdUTRA-FDD (396)–PhysCellIdUTRA-TDD (396)–PLMN-Identity (397)–PLMN-IdentityList3 (397)–PreRegistrationInfoHRPD (397)–Q-QualMin (398)–Q-RxLevMin (398)–Q-OffsetRange (398)–Q-OffsetRangeInterRAT (399)–ReselectionThreshold (399)–ReselectionThresholdQ (399)–SCellIndex (399)–ServCellIndex (400)–SpeedStateScaleFactors (400)–SystemInfoListGERAN (400)–SystemTimeInfoCDMA2000 (401)–TrackingAreaCode (401)–T-Reselection (402)–T-ReselectionEUTRA-CE (402)6.3.5Measurement information elements (402)–AllowedMeasBandwidth (402)–CSI-RSRP-Range (402)–Hysteresis (402)–LocationInfo (403)–MBSFN-RSRQ-Range (403)–MeasConfig (404)–MeasDS-Config (405)–MeasGapConfig (406)–MeasId (407)–MeasIdToAddModList (407)–MeasObjectCDMA2000 (408)–MeasObjectEUTRA (408)–MeasObjectGERAN (412)–MeasObjectId (412)–MeasObjectToAddModList (412)–MeasObjectUTRA (413)–ReportConfigEUTRA (422)–ReportConfigId (425)–ReportConfigInterRAT (425)–ReportConfigToAddModList (428)–ReportInterval (429)–RSRP-Range (429)–RSRQ-Range (430)–RSRQ-Type (430)–RS-SINR-Range (430)–RSSI-Range-r13 (431)–TimeToTrigger (431)–UL-DelayConfig (431)–WLAN-CarrierInfo (431)–WLAN-RSSI-Range (432)–WLAN-Status (432)6.3.6Other information elements (433)–AbsoluteTimeInfo (433)–AreaConfiguration (433)–C-RNTI (433)–DedicatedInfoCDMA2000 (434)–DedicatedInfoNAS (434)–FilterCoefficient (434)–LoggingDuration (434)–LoggingInterval (435)–MeasSubframePattern (435)–MMEC (435)–NeighCellConfig (435)–OtherConfig (436)–RAND-CDMA2000 (1xRTT) (437)–RAT-Type (437)–ResumeIdentity (437)–RRC-TransactionIdentifier (438)–S-TMSI (438)–TraceReference (438)–UE-CapabilityRAT-ContainerList (438)–UE-EUTRA-Capability (439)–UE-RadioPagingInfo (469)–UE-TimersAndConstants (469)–VisitedCellInfoList (470)–WLAN-OffloadConfig (470)6.3.7MBMS information elements (472)–MBMS-NotificationConfig (472)–MBMS-ServiceList (473)–MBSFN-AreaId (473)–MBSFN-AreaInfoList (473)–MBSFN-SubframeConfig (474)–PMCH-InfoList (475)6.3.7a SC-PTM information elements (476)–SC-MTCH-InfoList (476)–SCPTM-NeighbourCellList (478)6.3.8Sidelink information elements (478)–SL-CommConfig (478)–SL-CommResourcePool (479)–SL-CP-Len (480)–SL-DiscConfig (481)–SL-DiscResourcePool (483)–SL-DiscTxPowerInfo (485)–SL-GapConfig (485)。
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an introduction to boundary layer
meteorology -回复
什么是边界层气象学？
边界层气象学是大气科学的一个分支，研究地球表面与底层大气之间相互作用的过程和现象。
边界层是地球气候系统中非常重要的一部分，它直接与地表相接触，承载着大气中的能量、质量和动量传输。
了解和研究边界层气象学对于深入理解气象现象，如风、温度、湿度和降水等的形成和演变具有关键作用。
1. 边界层的定义和特点
边界层是地球表面与底层大气之间的薄层，通常为几百米至几千米的范围。
它的特点包括：边界层内大气的运动主要受地表条件限制；空气中的运动速度和湍流强度较大；湍流混合比较充分，使得能量、质量和动量的交换较为强烈。
2. 边界层与气象现象的关系
边界层对于气象现象的形成和发展具有重要影响。
例如，风是由于大气中的气压差驱动而产生的，而气压的分布受到地表条件的直接影响，边界层的存在会使风的运动变得复杂；温度和湿度分布也受到边界层的影响，例如，白天地表受到太阳辐射的加热，空气被加热后上升，形成对流层，而在夜间，地面降低温度，边界层高度减小，形成边界层逆温。
3. 边界层的结构和发展
边界层的结构可以分为水平结构和垂直结构。
水平结构包括边界层内的湍流运动和大气中的水平风场分布；垂直结构包括边界层高度变化、温度和湿度的垂直分布等。
边界层的发展与地表条件、大气环流、辐射等因素密切相关。
例如，地表条件的不均匀性会使边界层产生湍流，并引起气旋涡的产生；大气环流的影响会改变边界层的大小、稳定性和结构。
4. 边界层气象学的应用
边界层气象学的研究对于气象预报、环境污染控制、能源利用等方面具有重要价值。
通过研究边界层的结构和发展，可以更准确地预测天气和气候变化；边界层的湍流运动是城市空气污染物扩散的重要过程，了解边界层的特性有助于设计和改善城市环境；边界层中的风能和太阳能等可再生能源的利用也受到边界层气象学的研究。
总结：
边界层气象学是研究地球表面与底层大气之间相互作用的过程和现象的分支科学。
边界层的定义和特点、与气象现象的关系、结构和发展以及应用是边界层气象学的核心内容。
深入研究边界层气象学对于深化对气象现象的理解以及环境保护和可持续发展具有重要意义。