fluent算例-船舶航行
fluent经典算例
fluent经典算例Tutorial:Modeling a Single-Channel,Counter-Flow Polymer Electrolyte Membrane(PEM)Fuel CellIntroductionThe purpose of this tutorial is to provide guidelines and recommendations for using the PEM Fuel Cell add-on module available in FLUENT.This tutorial demonstrates how to do the following:Build and generate a mesh for a single-channel PEM fuel cell.Assign zone names and types that are required in the FLUENT PEM fuel cell add-onmodule.Import the mesh into FLUENT,set up the case,and run the calculations.Postprocess the results.PrerequisitesThis tutorial assumes you are familiar with both the GAMBIT and FLUENT interfaces and that you have a good understanding of the basic setup and solution procedures.Details of most steps will not be shown explicitly.If you have not used FLUENT before,it would be helpful to?rst refer to the FLUENT6.3 User’s Guide and theFLUENT6.3Tutorial Guide.You can also refer to the GAMBIT User’s Guide,GAMBIT Tutorial Guide,and GAMBIT Modeling Guide.Problem DescriptionA schematic description of a single,straight-channel,counter-?ow PEM fuel cell is shown inFigure1.The dimensions of the fuel cell are2.4×2.88×125mm in the x,y,and z directions, respectively.This model represents a repeating channel of a larger counter-?ow PEM fuel cell.The cross-sectional area of the membrane electrode assemblyis2.4×125=300mm2.All the zones as marked in Figure1(with exception of the optional cooling channel)must be de?ned as separate zones within GAMBIT.Note that there can be multiples of each zone.For example,there can be multiple cathode gas di?usion layers,each with di?erent material properties.In FLUENT6.3,all continuum zones must be of the?uid type except for the current collectors which may be either solid or? uid.For simplicity,it is recommended that you make the current collectors solid continuum zones.Modeling a Single-Channel,Counter-Flow Polymer Electrolyte Membrane(PEM)Fuel CellFigure1:PEM Fuel Cell ZonesFor details about the FLUENT PEMFC model,refer to o f FLUENT6.3Fuel Cell ModulesManual.Note:If you would like to bypass all GAMBIT steps and proceed to the FLUENT portion of the tutorial,skip to Step. Preparation in GAMBIT1.Create a folder called pem-single-channel to contain the?les generated in thistutorial.2.Start GAMBIT and specify this folder as the working folder.To simplify the geometry construction and meshing steps,a journal?le,pem-single-channel.jou is provided.This?le contains GAMBIT instructions which will create the geometry and gen-erate the mesh.It is recommended that you step through the journal?le to understand eachof the steps and recognize the assigned zone boundary types pertinent to fuel cell problems.Geometry Creation and Mesh GenerationStep1:Geometry Creation1.Create a rectangular face primitive in the xy plane.Operation?→Geometry?→Face?→Create Real Rectangular Face(a)Enter2.4for Width and1.2for Height.Modeling a Single-Channel,Counter-Flow Polymer Electrolyte Membrane(PEM)Fuel Cell(b)Select+X+Y for Direction,(c)Click Apply and close the Create Real Rectangular Face panel.2.Create another face by sweeping the uppermost edge by0.21units in the y-direction.Operation?→Geometry?→Face?→Sweep Edges3.Create another face by sweeping the uppermost edge by0.012units in the y-direction.4.Create another face by sweeping the uppermost edge by0.036units in the y-direction.5.Create another face by sweeping the uppermost edge by0.012units in the y-direction.6.Create another face by sweeping the uppermost edge by0.21units in the y-direction.7.Create another face by sweeping the uppermost edge by1.2units in the y-direction.8.Create a rectangular face with dimensions(x,y)=(0.8,0.6).Use+x+y for the di-rection(so that the global coordinate system origin is in the lower left corner of theface).9.Move the newly created face using a vector of(0.8,0.6,0).Operation?→Geometry?→Face?→Move/Copy Faces10.Copy the face by1.08units in the y-direction.11.Split the lowermost face with the face you just created.Operation?→Geometry?→Face?→Split Face12.Similarly,split the uppermost face with its internal face.The resulting mesh should appear as shown in Figure2.Step2:Mesh Generation(Manual)1.Mesh the edges as shown in Figure2.The numbers of cells along each edge are indicated below.The geometry and mesh are symmetric about its horizontal midplane.Operation?→Mesh?→Edge?→Mesh Edges2.Mesh the nine faces using the Quad Submap scheme.Operation?→Mesh?→Face?→Mesh Faces3.Create an edge by sweeping any one of the vertices by125units in the positive z direction.Operation?→Geometry?→Edge?→Sweep VerticesModeling a Single-Channel,Counter-Flow Polymer Electrolyte Membrane(PEM)Fuel CellFigure2:Edge and Face Mesh(a)Select Vector for Path and click the De?ne button.(b)Enable Magnitude and enter125.(c)Select Positive for Z from the Direction list.(d)Click Apply in the Vector De?nition form.(e)Click Apply and close the Sweep Vertices form.4.Mesh the newly created edge using a double-sided graded edge mesh that consists of 60elements.(a)Enable Double sided.(b)Enter1.1for Ratio1and Ratio2.(c)Click Apply and close the Mesh Edges form.5.Create volumes by sweeping the nine faces along the newly created edge. Operation?→Geometry?→Volume?→Sweep Faces(a)Enable With Mesh.(b)Click Apply and close the Sweep Faces form.The volume mesh is as shown in Figure3.Modeling a Single-Channel,Counter-Flow Polymer Electrolyte Membrane(PEM)Fuel CellFigure3:Volume MeshStep3:Zone Assignments and Mesh ExportFLUENT’s PEM fuel cell add-on module requires that boundary and continuum zones berigorously de?ned.Care should be taken in order to have a logical system of naming eachzone to represent each of the regions shown in Figure1.At a minimum,the boundary zones that are required include the following:Inlet and outlet zones for the anode gas channel.Inlet and outlet zones for the cathode gas channel.Surfaces representing anode and cathode terminals.Optional boundary zones that could be de?ned include any voltage jump surfaces,interiorow surfaces,or non-conformal interfaces that are required.The following continuum zones are also required:Flow channels for anode-and cathode-sideuids.Anode and cathode current collectors.Anode and cathode gas diusion layers.Anode and cathode catalyst layers.Electrolyte membrane.The inlets should all be assigned the boundary zone type MASS FLOW INLET and outletsshould be assigned the PRESSURE OUTLET type.The terminals are the regions where thevoltage(or current?ux density)is known.Normally,the anode is grounded(V=0)andModeling a Single-Channel,Counter-Flow Polymer Electrolyte Membrane(PEM)Fuel Cell the cathode terminal is at a?xed potential that is less than the open-circuit potential.Bothof the terminals should be assigned the WALL boundary type.Voltage jump zones can optionally be placed between the various components(such asbetween the gas di?usion layer and the current collector).Faces which represent?uid/solidinterfaces must be of type WALL.Additional interior zones may be de?ned for purposes of post-processing.If such interiorzones are de?ned,they should have no e?ect on the solution.FLUENT’s PEM add-on module supports the use of non-conformal grid interfaces.In such cases,it is recommended that the INTERFACE boundary type be used halfway between the membrane continuum zone,and that the mesh on opposite sides of the interface have similar size,aspect ratio,and orientation.In such cases,the membrane will consist of two uid zones.1.Assign boundary zones according to the de?nitions listed in Table1.Operation?→Zones?→Specify Boundary TypesTable1:Boundary Zone AssignmentsAnode-side inlet(z=125,upper)inlet-a MASS FLOW INLETCathode-side inlet(z=0,lower)inlet-c MASS FLOW INLETAnode-side outlet(z=0,upper)outlet-a PRESSURE OUTLETCathode-side outlet(z=125,lower)outlet-c PRESSURE OUTLETAnode terminal(y=2.88)wall-terminal-a WALLCathode terminal(y=0)wall-terminal-c WALLAnode-side?ow channel walls wall-ch-a WALLCathode-side?ow channel walls wall-ch-c WALLFuel cell ends wall-ends WALLAnode-side di?usion layer walls wall-gdl-a WALLCathode-side di?usion layer boundaries wall-gdl-c WALLLateral boundaries of the fuel cell wall-sides WALL2.Assign continuum zones according to the de?nitions listed in Table2.Refer to Figure1 when selecting which volumes to assign to each zone.Operation?→Zones?→Specify Continuum TypesModeling a Single-Channel,Counter-Flow Polymer Electrolyte Membrane(PEM)Fuel Cell Table2:Continuum Zone AssignmentsAnode-side catalyst layer catalyst-a FLUIDCathode-side catalyst layer catalyst-c FLUIDAnode-side?ow channel channel-a FLUIDCathode-side?ow channel channel-c FLUIDAnode-side gas di?usion layer gdl-a FLUIDCathode-side gas di?usion layer gdl-c FLUIDElectrolyte membrane membrane FLUIDAnode current collector current-a SOLIDCathode current collector current-c SOLID3.Export the mesh?le as pem-single-channel.msh.Setup and Solution in FLUENTFLUENT’s PEM Fuel Cell(PEMFC)model is provided as an add-on module with thestandard FLUENT licensed software.A special license is required in order to use thismodel.The module is installed as part of the standard FLUENT installation in the folder/addons/fuelcells2.2within the FLUENT installation folder.The PEMFC model con-sists of a user-de?ned function(UDF)library and a compiled Scheme library which can beloaded using a text user interface(TUI)command.trtitlePreparation1.Copy the mesh?le pem-single-channel.msh.gz to your working folder.If you worked through the GAMBIT portion of this tutorial,an uncompressed versionof this?le will already be in place.2.Start the3DDP(3ddp)version of FLUENT.!If you wish to solve this case in parallel,you will need to set up and save the case?le in serial mode?rst.Once this is done,you can start a parallel FLUENTsession and proceed with the calculations.Step1:Grid1.Read the mesh?le,pem-single-channel.msh.gz.File?→Read?→Case...FLUENT will perform various checks on the mesh and will report the progress in theconsole window.Make sure that the reported minimum volume is a positive number.2.Check the grid.Grid?→CheckA grid check should always be performed in order to verify the integrity of the meshle.Specically,you should verify that the minimum cell volume is a positive value.Modeling a Single-Channel,Counter-Flow Polymer Electrolyte Membrane(PEM)Fuel Cell3.Since the mesh was created in units of millimeters,it must be scaled.Grid?→Scale...(a)Select mm from the Grid Was Created In drop-down list.(b)Click the Change Length Units button.(c)Click Scale.(d)Verify that the value of Zmax is125mm and close the Scale Grid panel.Step2:Models1.To load the PEMFC model using the text user interface,enter the following commandin the console:/define/models/addon-module3This command will load a Scheme library which contains the PEM model GUI anda UDF library.Upon successful execution,the following message will be displayed inthe console:Addon Module:fuelcells2.2...loaded!2.Calculate the surface area of the membrane for post-processing.In this case,the membrane area is equal to the surface area of the cathode terminal. This surface is named wall-terminal-c.Report?→Projected Areas...(a)Select Y from the Projection Direction group box.(b)Select wall-terminal-c from the Surfaces list.(c)Click Compute.The projected area reported is0.0003m2.(d)Close the Projected Surface Areas panel.3.Change the Solution Zones for user-de?ned scalars2and3to all zones.De?ne?→User-De?ned?→Scalars...This is an optional step which allows UDS-2and UDS-3to be postprocessed on bothuid and solid zones.4.Con?gure the PEM model.De?ne?→Models?→PEMFC...(a)Click the Anode tab.Modeling a Single-Channel,Counter-Flow Polymer Electrolyte Membrane(PEM)Fuel Cell i.Select Current Collector in the Anode Zone Type group box and select current-a from the Zone(s)selection list.ii.Select Flow Channel in the Anode Zone Type group box and select channel-afrom the Zone(s)selection list.iii.Select Di?usion Layer in the Anode Zone Type group box and select gdl-a fromthe Zone(s)selection list.iv.Select Catalyst Layer in the Anode Zone Type group box and select catalyst-afrom the Zone(s)selection list.(b)Click the Membrane tab.i.Select membrane from the Membrane Zone(s)selection list.(c)Click the Cathode tab.i.Select Current Collector in the Cathode Zone Type group box and selectcurrent-c from the Zone(s)selection list.ii.Select Flow Channel in the Cathode Zone Type and select channel-c from theZone(s)selection list.iii.Select Di?usion Layer in the Cathode Zone Type and select gdl-c from theZone(s)selection list.iv.Select Catalyst Layer in the Cathode Zone Type and select catalyst-c from theZone(s)selection list.(d)Click the Reports tab.i.Specify the value of Membrane-Electrode-Assembly Projected Area to0.0003m2. Recall that this value was obtained earlier in the tutorial.ii.Select wall-terminal-a from the Anode selection list and select wall-terminal-cfrom the Cathode selection list.(e)Click OK to close the PEM panel.FLUENT reports in the console that the energy equation has been enabled auto-matically.For convenience,the PEMFC model also automatically enables species transport and creates default materials.Step3:MaterialsRetain the default settings for the materials.Step4:Operating ConditionsDe?ne?→Operating Conditions...1.Set the Operating Pressure to200000pascal.2.Click OK to close the Operating Conditions panel.Modeling a Single-Channel,Counter-Flow Polymer Electrolyte Membrane(PEM)Fuel Cell Step5:Boundary ConditionsDe?ne?→Boundary Conditions...There are several zones which must be speci?ed in the boundary conditions panel.These are the anode and cathode voltage terminals,as well as the inlets and outlets.1.Set boundary conditions for the anode voltage terminal,wall-terminal-a.At this surface,the voltage is grounded and the temperature is constant.(a)Click the Thermal tab and enter353K for Temperature.(b)Click the UDS tab.i.Select Speci?ed Value from the Electric Potential drop-down list User-De?nedScalar Boundary Condition group box.ii.Enter0for Electric Potential in the User-De?ned Scalar Boundary Value groupbox.This boundary condition represents a grounded terminal.(c)Click OK to close the Wall panel.2.Set boundary conditions for the cathode voltage terminal,wall-terminal-c.At this surface,the voltage is maintained at a constant,positive value.(a)Click the Thermal tab and enter353K for Temperature.(b)Click the UDS tab.i.Select Speci?ed Value from the Electric Potential drop-down list User-De?nedScalar Boundary Condition group box.ii.Enter0.75for Electric Potential in the User-De?ned Scalar Boundary Valuegroup box.This boundary condition represents a terminal operating at0.75Volts.iii.Click OK to close the Wall panel.To calculate an IV polarization curve,you should vary the Electric Potential forthe cathode,starting from a voltage near the open circuit voltage and gradually decreasing it,converging the solution each time you change the value.3.Set boundary conditions for the anode gas?ow inlet,inlet-a.At this inlet,a humidi?ed hydrogen stream enters the fuel cell.No liquid enters the channel.(a)Enter6.0e-7kg/s for Mass Flow Rate and0for Supersonic/Initial Gauge Pressure.(b)Click the Thermal tab and enter353K for Temperature.(c)Click the Species tab and set the mass fractions of h2,o2and h2o to0.8,0.0,and0.2,respectively.(d)Click the UDS tab and select Speci?ed Value from the Water Saturation drop-down list in the User-De?ned Scalar Boundary Condition group box.Modeling a Single-Channel,Counter-Flow Polymer Electrolyte Membrane(PEM)Fuel Cell(e)Enter0for Water Saturation in the User-De?ned Scalar Boundary Value group box.(f)Click OK to close the Mass-Flow Inlet panel.4.Set boundary conditions for the cathode gas?ow inlet,inlet-c.At this inlet,a humidi?ed air stream enters the fuel cell.No liquid enters the channel.(a)Enter5.0e-6kg/s for Mass Flow Rate.(b)Click the Thermal tab and enter353K for Total Temperature.(c)Click the Species tab and set the mass fractions of h2,o2and h2o to0.0,0.2,and0.1,respectively.(d)Click the UDS tab and select Speci?ed Value from the Water Saturation drop-down list in the User De?ned Scalar Boundary Condition group box.(e)Enter0for Water Saturation in the User-De?ned Scalar Boundary Value group box.(f)Click OK to close the Mass-Flow Inlet panel.5.Set boundary conditions for the anode gas?ow outlet,outlet-a.(a)Click the Thermal tab and enter353K for Back?ow Total Temperature.(b)Click OK to close the Pressure Outlet panel.6.To set boundary conditions for the cathode gas?ow outlet,copy the boundary con-ditions from outlet-a to outlet-c7.Close the Boundary Conditions panel.Step6:Solution ControlsThe default solver settings are not su?cient to obtain a converged solution.Therefore,the following modi?cations must be made.1.Set the under-relaxation factor for Pressure to0.7,Momentum to0.3,Protonic Po-tential to0.95,and Water Content to0.95.Solve?→Controls?→Solution...2.Modify the multigrid settings.Solve?→Controls?→Multigrid...(a)Select F-Cycle from the Cycle Type drop-down lists for all equations.You will need to scroll down to set all equations.(b)Enter0.001for Termination Restriction for h2,o2,h2o,and Water Saturation.(c)Select BCGSTAB from the Stabilization Method drop-down list for h2,o2,h2o,Water Saturation,Electric Potential and Protonic Potential.(d)Enter0.0001for Termination Restriction for Electric Potential and Protonic Po-tential.(e)Increase the value of Max Cycles to50in the Algebraic Multigrid Controls group box.Modeling a Single-Channel,Counter-Flow Polymer Electrolyte Membrane(PEM)Fuel Cell(f)Click OK to close the Multigrid Controls panel.3.Enable the plotting of residuals.Solve?→Monitors?→Residual...Note:The PEMFC model automatically disables convergence checking for all equa-tions.4.Initialize the solution.Solve?→Initialize?→Initialize...(a)Set Temperature to353K.(b)Click Apply.(c)Click Init and close the Solution Initialization panel.5.Save the case and data?les as pem-single-channel.cas.gz andpem-single-channel.dat.gz.File?→Write?→Case&Data...!If you want to run the calculations in parallel,exit FLUENT and start a parallel session at this point.Open the case and data? les you saved in the previousstep and proceed.6.Request200iterations.The solution residuals will drop to acceptable values.Solve?→Iterate...The solution residual plot should resemble that shown in Figure4.The average currentdensity is displayed in the console at the end of each iteration.At the end of the calculations,the current density is reported as approximately0.324A/cm2.Step7:Postprocessing1.Create surfaces for postprocessing.Surface?→Iso-Surface...(a)Select Grid...and Z-Coordinate from the Surface of Constant drop-down lists.(b)Click Compute.(c)Enter62.5for Iso-Values(mm).(d)Enter plane-xy for New Surface Name.(e)Click Create.(f)Similarly,create another surface along the length of the fuel cell.This surfaceshould be a surface of constant X-Coordinate,with a value /doc/d88704d349649b6648d74700.html this surface plane-yz.(g)Close the Iso-Surface panel.Modeling a Single-Channel,Counter-Flow Polymer Electrolyte Membrane(PEM)Fuel CellFigure4:Residual Plot2.Create custom vectors for display.Display?→Vectors...(a)Click the Custom Vectors...button to open the Custom Vectors panel.i.Enter current-?ux-density for Vector Name.ii.Select User De?ned Memory...and X Current Flux Density from the X Com-ponent drop-down lists.iii.Select User De?ned Memory...and Y Current Flux Density from the Y Com-ponent drop-down lists.iv.Select User De?ned Memory...and Z Current Flux Density from the Z Com-ponent drop-down lists.v.Click De?ne and close the Custom Vectors panel.(b)Select current-?ux-density from the Vectors of drop-down list.(c)Select?lled-arrow from the Style drop-down list.(d)Click the Vector Options...button to open the Vector Options panel.i.Enter0.5for Scale Head.ii.Click Apply and close the Vector Options panel.(e)Select User-De?ned Memory and Current Flux Density Magnitude from the Colorby drop-down lists.(f)Enable Draw Grid from the Options list to open the Grid Display panel.i.Deselect all surfaces except plane-xy from the Surfaces selection list.Modeling a Single-Channel,Counter-Flow Polymer Electrolyte Membrane(PEM)Fuel CellFigure5:Current Flux at a Cross-Section Midway Down the Length of the PEM Channel ii.Ensure that Edges is enabled from the Options list and Feature is selectedfrom the Edge Type list.iii.Click Display and close the Grid Display panel.(g)Select plane-xy in the Surfaces selection list.(h)Click Display and close the Vectors panel.3.Auto-?t the display to the graphics window by pressing Ctrl-A on the keyboard./doc/d88704d349649b6648d74700.html pare your results with those shown in Figure5.Note:The maximum current density occurs in the regions between the channels and also that the plot units are A/m2.5.Plot contours of hydrogen mass fraction along the surface plane-yzDisplay?→Contours...(a)Enable Filled and Draw Grid from the Options list.(b)Select plane-yz from the Surfaces selection list in the Grid Display panel.(c)Click Display and close the Grid Display panel.(d)Restore the right view.Display?→View...i.Select right from the Views selection list.ii.Click Apply and close the Views panel.The display updates to the right-hand view.Modeling a Single-Channel,Counter-Flow Polymer Electrolyte Membrane(PEM)Fuel CellFigure6:Contours of Hydrogen Mass Fraction Along the Channel Length(e)Select plane-yz from the Surfaces selection list.(f)Select Species...and Mass fraction of h2from the Contours of drop-down lists.(g)Click Display.The resulting display is di?cult to visualize since the aspect ratio of the channelis large.You can change the way FLUENT displays data using the following steps:Display?→Scene...i.Select all entries from the Names selection list.ii.Click the Transform...button to open the Transformations panel.iii.Set Z to0.1in the Scale group box.iv.Click Apply and close the Transformations panel.The graphics display will be scaled accordingly.(h)Auto-?t the image to the window by pressing Ctrl-A in the graphics window.(i)Compare your result with that shown in Figure6.The?ow in the anode(upper)channel is from left to right.Note that the hydrogenmass fraction decreases in the direction of?ow.This is due to water being pulled through the membrane along with hydrogen as it is consumed in the fuel cell.6.Plot contours of oxygen mass fraction along the surface plane-yzDisplay?→Contours...(a)Follow the same procedure to generate the oxygen mass fraction contour plotthat you used to generate the hydrogen mass fraction contours.Modeling a Single-Channel,Counter-Flow Polymer Electrolyte Membrane(PEM)Fuel CellFigure7:Contours of Oxygen Mass Fraction Along the Channel Length(b)Compare your result with that shown in Figure7.The?ow in the cathode(lower) channel is from right to left.As expected,the oxygen mass fraction decreases inthe direction of?ow.7.Verify that global conservation of mass is observed.This will be done using a few text user interface(TUI)commands and basic electrochemistry concepts.(a)Compute the net oxygen consumption.Enter the TUI command:/report/species-mass-flowIf you have read a data?le instead of performing iterations,you must performat least one iteration in order to populate this data from the solver.The output is as follows:zone22(inlet-a):(4.8e-0701.2e-07)zone21(inlet-c):(01e-065e-07)zone20(outlet-a):(-4.6958153e-07-8.9805489e-11-2.8157297e-07)zone19(outlet-c):(-2.6251551e-10-9.1930928e-07-4.2904232e-07)zone53(wall-ch-a-shadow):(000)zone15(wall-ch-c):(000)zone29(wall-ends:029):(000)zone30(wall-ends:030):(000)zone31(wall-ends:031):(000)zone32(wall-ends:032):(000)zone33(wall-ends:033):(000)Modeling a Single-Channel,Counter-Flow Polymer Electrolyte Membrane(PEM)Fuel Cell zone51(wall-gdl-a-shadow):(000) zone11(wall-gdl-c):(000)zone1(wall-sides:001):(000)zone23(wall-sides:023):(000)zone25(wall-sides:025):(000)zone26(wall-sides:026):(000)zone27(wall-sides:027):(000)net species-mass-flow:(1.0155954e-088.0600915e-08-9.061529e-08)To interpret the output,each line can be read aszone num(zone-name):(˙m1˙m2...˙m n)where the subscripts1,2,...,nrefer to each species being calculated.Here,we are considering three species,namely h2,o2and h2o.Therefore,the second value in each list is the calculatedoxygen mass?ow rate in kilograms per second.In addition,a negative numberindicates?ow out of the domain from that boundary.From the last line,the netoxygen consumed is8.06×10?8kg/s.The molecular weight of oxygen is31.9988kg/kmol.Also,since the valence of a diatomic oxygen molecule is4,there are4kmol of electrons released per kmol of oxygen.Finally Faraday’s constant is9.6485×107C/kmol-electrons.Thus,the total release of electrons(which isequivalent to the current in Amperes),isI=˙mv FM=(8.06×10?8)(4.0)(9.6485×107)31.9988=0.972A(1)The total current is obtained by integrating the current density over the surface of the terminal.This integral value can be calculated in several ways.One way is to multiply the membrane area by the reported current density.This givesI=(0.0003)(0.3241)(100)2=0.972A(2) Alternatively,you can integrate the user memory Y Current Flux Density(the y-component of current density)over the terminal surface.This integration yields an accurate result since the y-direction is normal to the terminal.To do this, use the Surface Integrals panel.Report?→Surface Integrals...i.Select Report Type from the Integral drop-down list.ii.Select User De?ned Memory...and Y Current Flux Density from the Field Variable drop-down lists.iii.Select wall-terminal-a from the Surfaces selection list and click Compute.The absolute value of the number reported is approximately0.972A.We have electrochemical balance in the calculations. iv.Close the Surface Integrals panel.Modeling a Single-Channel,Counter-Flow Polymer Electrolyte Membrane(PEM)Fuel CellSummaryIn this tutorial,you learned how to set up and model a single-channel PEM fuel cell.Themodel provides detailed information on the distribution of current and voltage on all theelectrically conducting regions,along with species and current?ux density distributionthroughout the fuel cell.。
fluent 简单算例
1.GAMBIT建模（1）操作1;双击桌面“GAMBIT快捷方式”进入操作空间，如下图图1几何模型创建遵循原则：按组成几何模型的几何拓扑结构，由低层向高层创建，即按由点到面，再到体的顺序创建（这样减的好处是便于网格的划分和Fluent求解时边界条件的设定，缺点是步骤繁琐）。
对于较简单的模型，可省略低拓扑结构，直接建立最终模型。
（2）创建节点操作2：鼠标左键依次单击Operation Geometry进入下图图2操作3：左键单击上图Apply，创建第一个点（坐标（0、0、0）），如下图，可以发现坐标原点显示白色图3操作4：在上图2中Global下输入x：200，y：0，z: 0，左键单击Apply, 如下图，操作5：左键单击（作用：窗口显示），如下图重复操作4和操作5，以此建立点（0，-0.0025,0）、（0.05，-0.0025，0）、（0.05、-0.0125）（0.15,0.0025,0），（0.15,0.0125，0），（0.2,0.0025），如下图，（3）节点成线操作1：左键依次单击，然后Shift+鼠标左键依次（为沿围成图形各点顺序）单击所创建的点，如下图，左键单击Apply，如下图，（4）连线成面操作1：左键单击，Shift+左键依次单击图中各线段，如下图，左键单击Apply，如下图，（5）网格划分网格划分遵循原则与模型创建类似操作1：左键依次单击，如下图，操作2：Shift+左键选中模型中一条边操作3：左键单击，弹出菜单中选择interval count，在左侧输入框中输入;200(为该条边上网格节点数)，如下图重复操作2和操作3，将沿y方向的短边和长边节点数分别设定为20和80.注意：对于相互平行两边，节点设置可只在一边进行；如果两边均设定，切记两边节点数要一致。
操作4：左键单击，Shift+左键单击图中任一边，所有边显示红色，然后左键单击Apply，如下图，（6）设置边界类型操作1: 左键单击，如下图，操作2：Shift+左键单击模型最左侧沿y方向的短边（显红色），单击，弹出菜单中选择PRESSURE-INLET，左键单击Apply，如下图，操作3：Shift+左键单击模型最右侧沿y方向的短边（显红色），单击，弹出菜单中选择PRESSURE-OUTLET，左键单击Apply，如下图，操作4：其它边不设置，默认为壁面条件。
FLUENT算例 (9)
计算流体力学作业FLUENT 模拟燃烧问题描述：长为2m、直径为0.45m的圆筒形燃烧器结构如图1所示，燃烧筒壁上嵌有三块厚为0.0005 m，高0.05 m的薄板，以利于甲烷与空气的混合。
燃烧火焰为湍流扩散火焰。
在燃烧器中心有一个直径为0.01 m、长为0.01 m、壁厚为0.002 m的小喷嘴，甲烷以60 m/s的速度从小喷嘴注入燃烧器。
空气从喷嘴周围以0.5 m/s的速度进入燃烧器。
总当量比大约是0.76(甲烷含量超过空气约28%)，甲烷气体在燃烧器中高速流动，并与低速流动的空气混合，基于甲烷喷嘴直径的雷诺数约为5.7×103。
假定燃料完全燃烧并转换为:CH4+2O2→CO2+2H2O反应过程是通过化学计量系数、形成焓和控制化学反应率的相应参数来定义的。
利用FLUENT的finite-rate化学反应模型对一个圆筒形燃烧器内的甲烷和空气的混合物的流动和燃烧过程进行研究。
1、建立物理模型，选择材料属性，定义带化学组分混合与反应的湍流流动边界条件2、使用非耦合求解器求解燃烧问题3、对燃烧组分的比热分别为常量和变量的情况进行计算，并比较其结果4、利用分布云图检查反应流的计算结果5、预测热力型和快速型的NO X含量6、使用场函数计算器进行NO含量计算一、利用GAMBIT建立计算模型第1步启动GAMBIT，建立基本结构分析：圆筒燃烧器是一个轴对称的结构，可简化为二维流动，故只要建立轴对称面上的二维结构就可以了，几何结构如图2所示。
(1)建立新文件夹在F盘根目录下建立一个名为combustion的文件夹。
(2)启动GAMBIT(3)创建对称轴①创建两端点。
A(0,0,0)，B(2,0,0)②将两端点连成线(4)创建小喷嘴及空气进口边界②连接AC、CD、DE、DF、FG。
(5)创建燃烧筒壁面、隔板和出口②将H、I、J、K、L、M、N向Y轴负方向复制，距离为板高度0.05。
③连接GH、HO、OP、PI、IJ、JQ、QR、RK、KL、LS、ST、TM、MN、NB。
FLUENT算例 (3)
三维圆管紊流流动状况的数值模拟分析在工程和生活中，圆管内的流动是最常见也是最简单的一种流动，圆管流动有层流和紊流两种流动状况。
层流，即液体质点作有序的线状运动，彼此互不混掺的流动；紊流，即液体质点流动的轨迹极为紊乱，质点相互掺混、碰撞的流动。
雷诺数是判别流体流动状态的准则数。
本研究用CFD 软件来模拟研究三维圆管的紊流流动状况，主要对流速分布和压强分布作出分析。
1 物理模型三维圆管长2000mm l =，直径100mm d =。
流体介质：水，其运动粘度系数62110m /s ν-=⨯。
Inlet ：流速入口，10.005m /s υ=，20.1m /s υ= Outlet ：压强出口Wall ：光滑壁面，无滑移2 在ICEM CFD 中建立模型2.1 首先建立三维圆管的几何模型Geometry2.2 做Blocking因为截面为圆形，故需做“O ”型网格。
2.3 划分网格mesh注意检查网格质量。
在未加密的情况下，网格质量不是很好，如下图因管流存在边界层，故需对边界进行加密，网格质量有所提升，如下图2.4 生成非结构化网格，输出fluent.msh 等相关文件3 数值模拟原理紊流流动当以水流以流速20.1m /s υ=，从Inlet 方向流入圆管，可计算出雷诺数10000υdRe ν==，故圆管内流动为紊流。
假设水的粘性为常数（运动粘度系数62110m /s ν-=⨯）、不可压流体，圆管光滑，则流动的控制方程如下：①质量守恒方程：()()()0u v w t x y zρρρρ∂∂∂∂+++=∂∂∂∂ (0-1)②动量守恒方程：2()()()()()()()()()()[]u uu uv uw u u ut x y z x x y y z z u u v u w p x y z xρρρρμμμρρρ∂∂∂∂∂∂∂∂∂∂+++=++∂∂∂∂∂∂∂∂∂∂'''''∂∂∂∂+----∂∂∂∂ (0-2)2()()()()()()()()()()[]v vu vv vw v v v t x y z x x y y z z u v v v w px y z yρρρρμμμρρρ∂∂∂∂∂∂∂∂∂∂+++=++∂∂∂∂∂∂∂∂∂∂'''''∂∂∂∂+----∂∂∂∂ (0-3)2()()()()()()()()()()[]w wu wv ww w w w t x y z x x y y z z u w v w w px y z zρρρρμμμρρρ∂∂∂∂∂∂∂∂∂∂+++=++∂∂∂∂∂∂∂∂∂∂'''''∂∂∂∂+----∂∂∂∂ (0-4)③湍动能方程：()()()()[())][())][())]t t k k t k k k ku kv kw k k t x y z x x y yk G z zμμρρρρμμσσμμρεσ∂∂∂∂∂∂∂∂+++=+++∂∂∂∂∂∂∂∂∂∂+++-∂∂ (0-5)④湍能耗散率方程：212()()()()[())][())][())]t t k k t k k u v w t x y z x x y y C G C z z k kεεμμρερερερεεεμμσσμεεεμρσ∂∂∂∂∂∂∂∂+++=+++∂∂∂∂∂∂∂∂∂∂+++-∂∂ (0-6)式中，ρ为密度，u 、ν、w 是流速矢量在x 、y 和z 方向的分量，p 为流体微元体上的压强。
基于fluent的阻力计算
基于fluent的兴波阻力计算本文主要研究内容本文的工作主要涉及小型航行器在近水面航行时的绕流场及兴波模拟和阻力的数值模拟两个方面。
在阅读大量文献资料的基础上，通过分析、比较上述领域所采用的理论和方法，针对目前需要解决的问题，选择合理的方法加以有机地综合运用。
具体工作体现在以下几个方面：1．本人利用FLUENT软件的前处理软件GAMBIT自主建立简单回转体潜器模型，利用FLUENT求解器进行计算，得出在不同潜深下潜器直线航行的绕流场、自由面形状及阻力系数的变化情况。
2．通过对比潜器在不同潜深情况下的阻力系数，论证了增加近水面小型航行器的深度可以有效降低阻力。
通过对模型型线的改动，为近水面小型航行器的型线设计提供了一定的参考。
通过改变附体形状和位置计算了附体对阻力的影响程度，为附体的优化设计提供了一定的依据。
计算模型航行器粘性流场的数值计算理论水动力计算数学模型的建立根据流体运动时所遵循的物理定律，基于合理假设（连续介质假设）用定量的数学关系式表达其运动规律，这些表达式成为流体运动的数学模型，它们是对流体运动的一种定量模型化，称为流体运动控制方程组。
根据控制方程组，结合预先给定的初始条件和边界条件，就可以求解反映流体运动的变量值，从而实现对流体运动的数值模拟预报，形成分析报告。
基于连续介质假设的流体力学中流体运动必须满足要遵循的物理定律:1) 质量守恒定律2）动量守恒定律3）能量守恒定律4）组分质量守恒方程针对具体研究的问题，有选择的满足上述四个定律。
船体的粘性不可压缩绕流运动，如果不考虑水温对水物理性质的影响，水的密度和分子粘性系数都是常数，同时没有能量的转换，就仅仅需要满足质量守恒定律、动量守恒定律。
在满足这些定律下所建立的数学模型称为Navier-Stokes方程。
另外，自由液面的存在也需要建立合适的数学模型。
本文是利用FLUENT 进行数值模拟，而软件里面关于自由液面模拟是用界面追踪方法的一种－流体体积法（VOF）,基于该方法所建立的数学模型称为流体体积分数方程。
中间渠道船舶航行阻力数值模拟计算
中间渠道船舶航行阻力数值模拟计算发布时间：2023-02-21T01:09:22.765Z 来源：《工程建设标准化》2022年19期10月作者：冯伟[导读] 中间渠道是一种特殊的限制性航道，船舶的航行阻力是确定其尺度的关键参数，而船舶航行阻力又与船舶航速,中间渠道的断面系数冯伟重庆交通大学重庆 400074摘要：中间渠道是一种特殊的限制性航道，船舶的航行阻力是确定其尺度的关键参数，而船舶航行阻力又与船舶航速,中间渠道的断面系数，下沉量有着一定的关系，本文采用数值模拟的方法，采用flow3d，测定了3000吨级单散货船在不同断面系数（1-5），不同航速下的船舶阻力值，通过对数值模拟结果进行分析，总结出船舶航行阻力变化的趋势关键字：中间渠道；数值模拟；船舶阻力1．中间渠道研究现状对于梯级船闸和升船机间，通常需要设置中间渠道来串联，中间渠道是一种两端封闭的限制性航道，然而，在我国《内河通航标准（GB 50139—2014）》中，对限制性航道和船闸尺度等均有规定，但对中间渠道这种特殊限制性渠道的断面尺度，尚未制定专门的通航标准。
本文通过对中间渠道船舶阻力进行数值模拟计算，以求探索出一种有关中间渠道的尺度的设计规范。
1.1国内研究现状关于中间渠道的研究，一方面，前人多以研究中间渠道内非恒定流水流特性，通航水流，以及渠道尺度与渠道内船舶航行方式等为主。
周华兴，高学平利用物理模型结合数学模型, 研究船闸泄水进入中间渠道后, 中间渠道内的水流条件与渠道尺度的关系。
根据波动特性,对渠道内水体波动进行了定义。
试验发现, 船闸泄水正波在前进中波前逐渐变陡, 到一定程度, 波前水体形状将不再稳定, 并形成短周期波。
1.2国外研究现状美国1953 年对 Welland 运河和船闸中间渠道的涌浪问题进行了原体观测和室内试验，提出减轻涌浪可采用降低灌泄水速度，加大河道尺度，制定合理的船闸运转方式、设调节池等方法1.3船舶阻力研究现状船舶阻力即是指的是船舶在航行中受到的阻力，一般分为三部分，一部分为兴波阻力Rw，一部分为船体摩擦阻力Rg ，一部分为黏剩余阻力Rvp，各种阻力成分在总阻力中所占比重在不同航速的船中是不相同的，对于低速船来说，摩擦阻力Rf占总阻力的70%-80%，黏剩余阻力Rvp约等于或大于10%，而兴波阻力Rw成分很小；对于高速船，Rf约占总阻力的40%-50%，而兴波阻力Rw却可达50%左右。
使用Fluent软件的螺旋桨敞水性能计算和考察_冯学梅
[研究与设计]使用Fluent 软件的螺旋桨敞水性能计算和考察①冯学梅1 陈凤明2 蔡荣泉1(1708研究所 上海 200011 2西北工业大学 西安 710072) [关键词]螺旋桨;敞水;C FD[摘 要]船舶性能CFD 计算领域有必要尽快形成螺旋桨敞水性能C FD 计算的快速预报能力,以快速响应用户的需求,使CFD 成为螺旋桨设计的手段之一,并利用这一手段,发挥CFD 计算结果信息量大的特点,对螺旋桨进行相关的性能考察计算。
文章介绍了708研究所利用Fluent 软件在螺旋桨敞水性能计算中的计算流程,以某船所使用的侧斜反弯扭桨作为研究对象,给出了敞水性能曲线的计算结果,并与试验测量值作了比较;同时还介绍了对此桨的性能情况所进行的一些数值计算考察。
[中图分类号]U661.7 [文献标识码]A [文章编号]1001-9855(2006)01-0014-06Calculation of propeller open water performanceby CFD software FLUENTFeng X uemei Chen Feng ming Cai Rong quanKeywords :Pro peller;Open Wa ter;CFDAbstract :M odern C FD calculation o f ship perfo rmance needs to hav e the capability of quick prediction of propeller open w ater perfo rm ance in o rder to prov ide quick response to custom er enquiry ,and to makeCFD one of the mea ns of propeller desig n .Suppo rted by its fea tures o f mass info rmatio n from CFD calcu-lation results,it can be also used to calculate a nd inv estigate releva nt pro peller perfo rm ance.The paper presents the w ork done in M ARIC to run the CFD softw are FLUEN T to calculate the open w ater perfo r-ma nce o f the pro peller ,the process of calcula tion ,the results of calcula tion o n o pen wa ter perfo rmance curv e of a pro peller w ith hig h skew a nd rake tip designed fo r a newbuilding design and a co mpa rison w ith the trial m easurement.The related calculation a nd inv estiga tion on the open w ater behavio r of this pro-peller is also repo rted .1 前 言螺旋桨模型单独地在均匀水流中试验称为敞水试验。
基于CFD方法的双体风电交通运维船改造的航速估算
基于CFD方法的双体风电交通运维船改造的航速估算赵敏华;关超;吴静萍【摘要】关于船舶改造,在设计阶段快速而又准确地估算航速相当重要.文章介绍针对某双体风电交通运维船的改造,采用数值仿真技术预报其航速.首先使用计算流体力学(CFD)商业软件FLUENT,对船舶在静水中的黏性阻力展开数值计算.然后通过黏性阻力占总阻力的比例,估算船舶的总阻力,绘制推进阻力曲线.从推进阻力曲线与螺旋桨的有效功率的交点即可估算出该船的航速.为了得到高精度黏性阻力计算结果,在船体表面附近网格加密,采用SST k-ω湍流模式,速度与压强耦合采用SIMPLC 方法,其它离散采用二阶迎风格式.数值方法预报船舶黏性阻力技术相当成熟,发表的数值预报结果供读者参考.【期刊名称】《中国修船》【年(卷),期】2018(031)002【总页数】4页(P13-16)【关键词】航速预报;数值模拟;黏性阻力;双体船【作者】赵敏华;关超;吴静萍【作者单位】天津新港船舶重工有限责任公司,天津300452;武汉理工大学交通学院,湖北武汉430063;武汉理工大学交通学院,湖北武汉430063【正文语种】中文【中图分类】U656.2关于船舶改造，在设计阶段快速而又准确地估算航速相当重要。
航速估算可以通过不同航速下阻力估算得到船舶的推进阻力曲线;然后根据主机功率和螺旋桨推进系数计算螺旋桨的有效功率，从而由推进阻力曲线和有效功率估算出航速［1］。
螺旋桨的有效功率通过估算船厂提供的主机功率或螺旋桨收到效率，考虑螺旋桨敞水效率、船身效率的影响，参考教材提供的数据［1］，估计1个敞水效率和船身效率，最后得到有效功率。
船舶主机功率确定之后，螺旋桨的有效功率比较容易估算，关键问题在于船舶的总阻力的估算。
船舶在波浪中航行，阻力主要包括黏性阻力、兴波阻力、空气阻力和波浪增阻4大部分。
对于中低速排水量型船舶，其中黏性阻力是主要部分，其它阻力成份，如兴波阻力、空气阻力和波浪增阻，各占一定比例［2］。
- 1、下载文档前请自行甄别文档内容的完整性，平台不提供额外的编辑、内容补充、找答案等附加服务。
- 2、"仅部分预览"的文档,不可在线预览部分如存在完整性等问题,可反馈申请退款(可完整预览的文档不适用该条件!)。
- 3、如文档侵犯您的权益，请联系客服反馈,我们会尽快为您处理(人工客服工作时间：9:00-18:30)。
CFD计算基础课程homework fluent目录一、问题描述 (2)二、建立模型 (3)2.1创建船体附近流域 (3)2.2确定边界条件， (5)三、用fluent进行求解计算 (5)3.1导入并检查网格 (5)3.2设置求解器参数 (6)3.3设置流体属性，选定空气和水 (7)3.4设置基本项和第一相 (7)3.5设置操作环境 (7)3.6设置边界条件 (7)3.7设置求解方法 (8)3.8流场初始化 (8)3.9定义初始空气区域 (9)3.10查看船体的初始湿面积 (9)3.11设置残差监视器以及升、阻力监视器 (9)3.12求解计算 (9)3.13升力报告 (11)3.14计算成果图 (11)四、第一次调整水线 (13)五、根据水线调整进行第二次建模 (14)六、对二次模型进行计算求解 (14)6.1升力报告 (14)6.2计算成果图 (14)6.3计算结果分析 (16)七、第二次调整水线 (16)八、根据水线调整进行第三次建模 (17)九、对三次模型进行求解计算 (17)一、问题描述一艘假想船，设船体高H=2m，船底长L=10m，船艏与水平线夹角α=45º；船头装有a=1m的压浪板，压浪板和水线的夹角为β=30º。
见图1.1。
若船体单位宽度上重为G=mg=17.5*103*9.81kg并以速度V=18km/h=5m/s均速行驶在平静的河水里，试研究此船舶的行驶过程和行驶阻力。
见图1.1分析（1）这应该是一个三维流动问题，为简化计算，采用二维模型。
即假设船体无限宽，忽略船体侧面对流动的影响。
（2）这是一个紊流流动问题，由于船体结构较复杂，必然引起紊流流动。
（3）这是一个气、液两相流问题，船体上部为空气，下部为水。
船舶在航行过程中必然引起水与空气之间的相互作用，并产生波浪。
（4）在仿真计算过程中，气液交界面的变化是一个逐渐趋于稳定状态的过程，故应该采用非稳定的计算方法。
（5）在船舶行驶过程中会对船体产生动升力，必然会引起船体的上下运动，并且影响船体的行驶阻力。
（6）船舶行驶过程中，在铅直方向有水的静浮力F f和动升力F d，由力的平衡可得，二者之和应等于船舶质量G。
假设静浮力F f为船舶质量的60%，即F f=λG,λ=0.6，由于浮力等于船舶排开水的质量，故有λG=ρg(Lℎ+12ℎ2)h=√L2+2λGρg−L=√102+2×0.6×17500×9.81998.2×9.81−10=1.0m得到初始水线为h=1.0m。
假设船舶行驶过程中的静浮力不变，若计算得到船体动升力为F d=(1−λ)G=0.4G，则船舶处于平衡状态，计算结束。
（7）流动区域的设置。
见图1.2a)设水线下水深为L，水下边界为固壁。
b)水线上面流域为2L高，初始为空气。
c)船舶前面流域沿流动方向长为3L。
d)船舶后部流域沿流动方向距离为5L。
e)船舶附近设置一个较小区域，便于对船体附近网格加密，以及改变水线后的建模。
图1.2二、建立模型2.1创建船体附近流域导入关键点，连接各点创建线，将船体和压浪板向下移动1.0m(初始水线为1.0m)，根据线创建面，创建网格，先创建线网格点分布，之后用map创建面网格，创建外围流域点、线、面及网格，网格创建方式类似于内部流域，但为了减少计算量，外围流域按一定比例逐渐变稀，在网格划分过程中我们共尝试采取三种网格布置，第一种网格布置（见图2.1）网格划分过密，计算量过大，计算耗时过长；第二种网格布置（见图2.2）网格划分过稀，计算结果难以收敛；综合各方面因素，最终采取第三种网格布置（见图2.3），既能保证计算精度，又相对耗时较短。
图2.1图2.2图2.32.2确定边界条件，见图2.4图2.4Gambit导出mesh文件命名为ship2d1.msh。
退出并保存session。
三、用fluent进行求解计算3.1导入并检查网格见图3.1图3.13.2设置求解器参数见图3.2、3.3选择VOF两相流计算模型，选择k-epsilon紊流模型。
图3.2 图3.33.3设置流体属性，选定空气和水见图3.4图3.43.4设置基本项和第一相基本相是水（water），第一相是空气（air），见图3.5图3.53.5设置操作环境重力加速度9.81m/s2，方向向下，操作环境密度1.225kg/m3，见图3.6图3.63.6设置边界条件将空气入流（inlet-air）和水入流（inlet-water）的入流速度（velocity-inlet）均设为5m/s，以及流域底部（bottom）的边界条件设为移动墙（moving wall），速度为5m/s。
3.7设置求解方法见图3.7图3.7 3.8流场初始化见图3.8图3.83.9定义初始空气区域见图3.9图3.93.10查看船体的初始湿面积见图3.10图3.10软件默认船体宽为1，所以初始时刻船体的湿面积计算方法：A0=(L+ℎ+√2ℎ)×1=(10+1+√2×1)×1=12.4143.11设置残差监视器以及升、阻力监视器3.12求解计算首先进行500个时间间隔的迭代计算，每个时间间隔为0.001秒，共0.5秒的时间，设置每个时间间隔最多迭代50次。
因为不确定求解至收敛所需时间，所以计算结果不断增加时间间隔数目，最后总共进行了27002个时间间隔的迭代计算（由于第一次计算的残差监视曲线和升、阻力监视曲线的图像忘记保存，这里附图为第二次计算的曲线，两次计算过程的性质类似，残差曲线见图3.11，升力曲线见图3.12，阻力曲线见图3.13）（由于计算量较大，最后时间没有把握好，望老师谅解）图3.11图3.12图3.13 3.13升力报告见图3.14图3.143.14计算成果图a)水气分布云图3.15图3.15 b)压力分布云图3.16图3.16 c)速度分布矢量图3.17图3.17四、第一次调整水线在行驶过程中，船体所受到的力既有水对其的浮力，又有水流和气流对其对其产生的阻力和动升力。
铅直方向受到重力、浮力和动升力的作用达到平衡状态。
最初的静浮力和动升力的比例是根据经验假定而来的，所以需要根据实际情况对水线进行调整。
水线调整的原则是：船体的浮力+动升力=船体的重力F d+F f=G但此时F d+F f=0.6×17.5×103×9.81+46525=149530NG=17.5×103×9.81=171675N∆F=G−(F d+F f)=171675−149530=22145N由于F d+F f<G，必然会使船体有所下降，或水线有所上升。
船体排水体积V p与水线h的关系如下：V p=Lℎ+1 2ℎ2水线h上升∆h将使排水体积增加∆V p，则有∆V p=（L+ℎ）∆h+12（∆ℎ）2如果将相差力∆F的60%转换为浮力的增大，即ρg∆V p=λ∆F=0.6∆F，则∆ℎ=√(L+ℎ)2+2λ∆Fρg−(L+ℎ)=√(10+1)2+2×0.6×22145998.2×9.81−(10+1)=0.122水线应上升0.122m，即水线变成h=1.122m，船体的排水面积增大了∆V p=(L+ℎ)∆h+12(∆ℎ)2=1.349m3所以V p=Lh+12h2+∆V p=11.849水对船体的静浮力ρgV p=116.029KN，另外由于船重171.675KN，故所需要的动升力为F d=G−F f=171.675−116.029=55.646KN若计算结果恰好等于所需的值，则船体处于平衡状态中，计算结束，否则还需要进一步调整。
五、根据水线调整进行第二次建模将空气进口和水进口的交界点提高0.122m，新建的模型如图5.1图5.1六、对二次模型进行计算求解求解方法和过程同第一次类似，这里不再详述，仅介绍计算结果。
6.1升力报告见图6.1图6.16.2计算成果图a)水气分布云图6.2图6.2 b)压力分布云图6.3图6.3c)速度分布矢量图6.4图6.46.3计算结果分析船体动升力F d=41.322KN，比预计少了55.646KN少了14.324KN，还需要进一步调整水线。
七、第二次调整水线此时∆F=G−(F d+F f)=14.324KN∆ℎ=√(L+ℎ)2+2λ∆Fρg−(L+ℎ)=√(10+1.122)2+2×0.6×14324998.2×9.81−(10+1.122)=0.079水线再上升0.079，即水线变为1.201，船体的排水体积变为V p=L(h+∆h)+12(h+∆ℎ)2=12.73m3水对船体的静浮力ρgV p=124.657KN，另外由于船重171.675KN，故所需要的动升力为F d=G−F f=171.675−124.675=47.018KN若计算结果恰好等于所需的值，则船体处于平衡状态中，计算结束，否则还需要进一步调整。
八、根据水线调整进行第三次建模将空气进口和水进口的交界点继续提高0.079 m，新建的模型如图8.1图8.1九、对三次模型进行求解计算求解方法和过程同前两次类似，这里不再详述，仅介绍计算结果。