新手入门fluent作业2的gambit and fluent基本操作

Lab. Guide for Assignment BLearning Objectives:1. Learn to use Gambit in creating the model geometry and generating a mesh with anacceptable quality.2. Learn to perform a preliminary CFD analysis using Fluent, and obtain the y+ values ofthe car body, as well as some basic CFD data, such as, the static pressure plot, velocity plot, and drag and lift coefficients in Fluent.In GambitStage 1. Create the model geometrya) Create the vertexes of the car body by entering the point coordinates provided in Table 1of the Assignment B paper.b) Create edges of the car body using NURBS edge creation algorithm with interpolation.c) Create the Face of the car body (the default Face name is Face 1).d) Create the vertexes of the computational domain (see Table 2).e) Create the 4 straight edges of the computational domain.f) Create the Face of the rectangular computational domain using the 4 straight edges ofthe rectangle (the default name is Face 2).g) Subtract Face 1 (i.e. car body) from Face 2 using Boolean operation. Note: DO NOTretain Face 1.h) Save the database as a separate geometry file:File→Save As, … to open the Save As panel:Figure 1. Numbers of edge mesh on each edge of the car body.b) Create a Boundary Layer meshMesh→Boundary Layer, to open the Create Boundary Layer panel: - Under Definitionc) Create a sizing functionTools→Size Function→Create Sizing function: - Under Type, select: Fixed- Under Entities:Graphics screen, the numbers of the highlighted elements next to Active Elements in the middle of the Examine Mesh panel, and the value of EquiAngle Stew shown in the Lower window directly above the slider cannel.Extra Topic - Estimating the 1st Grid Point LocationIn order to generate the mesh in the boundary layers, it is practical to compute the distance of the first layer 1y , using the following procedure:♦ Estimate the skin friction coefficient, f C ~, based on the correlations with approximate orempirical:For flat plates: 2.0Re 0359.02/~−≅f C ,where the Reynolds number is based on the length of the plate.♦Compute the frictional velocity: 2/~/f w C U U ∞==ρττ,where ∞U is the free stream velocity.♦ Back out the required distance from the wall for wall functions:τρµU y ⋅=2501,where µ is the dynamic viscosity and ρ is the density of the fluid.Note: The estimated value of y 1 is used as the value of the 1st row (a) when creating aboundary layer mesh, i.e .:The First row (a) value = y 12010.10.18NEUCFD LabIn Fluent Step 1 Open Fluent and Read in the .msh FileNote : choose: 2ddp (it means 2 d imensional, d ouble p recision)Step 2Check the Grid and Smooth/Swap GridGrid → CheckNote : pay attention to the minimum volume that can NOT be negative !Grid → Smooth/Swap- In the Smooth/Swap Grid panel, click on Smooth and Swap buttons repetitively until Fluent tells you that “No node moved, smoothing complete ” and “Number faces swapped: 0”.Step 3 Display the Grid (same procedure as in Assignment 1. Omit) Step 4Define the ModelDefine → Models → Viscous … , select : k-epsilon [2 eqn], then click OK. Note: (1) Note that value of Cmu (µC ) is 0.09. The µC value will be used forcalculating the Inlet boundary condition of the model.(2) under Near-Wall Treatment , there is a list of three wall functions used in k-ε model. The default one is “Standard Wall Function ”, which we are using in this analysis and the boundary layer mesh is developed based on the default Standard Wall Function used .Fluent also provide the option for User-defined Wall Functions for advanced users.Step 5Define Boundary ConditionsDefine → Boundary Conditions … to open the Boundary Conditions panel: -In the Boundary Conditions Panel , we define the following settings: (A) Inlet:(C) GroundStep 6Solve the Model(1) Open the Residual monitor, select Plot, leave the rest settings as the default, andthen exit the panel.(2) InitializeSolve→Initialize, then follow the same procedure as in Assignment 1. Omit.(3) IterateSolve→Iterate,Step 8Post-Processing in FluentA) Plot y+graph for the car bodyPlot→XY Plot, to open a X-Y Plot panel.:File name: Lab Guide for MIET2012 Assignment B:Author: Dr Yan DingSave Date: 11/08/09 RMIT University Page 11 of 11 (2) Obtain the Lift coefficientIntuitively, you should be able to follow the same procedure to calculate the Liftcoefficient in Fluent, using the max length of the car as the Reference Area value (see Figure 8) and give the Force Vector in the direction of Y (see Figure 9 )Figure 8. Settings for the reference valuefor the Lift coefficient inReference Values panel.Figure 9. Settings for the Lift report in theForce Report panel.C) Obtain the graphs of Static Pressure, Velocity, Turbulence Kinetic Energy, etc.The procedures are the same as in Assignment A, so omitted here.Step 9Exit Fluent File → ExitReference: [1] Tu, J., Yeoh, G. H. and Liu C., Computational Fluid Dynamics – A Practical Approach, 1stEdition 2008, Elsevier Inc. ISBN: 978-0-7506-8563-4, 39 Corporate Drive, Suite 400, Burlington, MA01803, USA.。