Verification and Validation of Turbulent Flow around a Clark-Y Airfoil58:160 Intermediate Mechanics of FluidsCFD LAB 2First input the refinement ratio used to create the “coarse” and “medium” meshes from the “fine” mesh.<<Monitor location>> is used to specify the locations for line monitors (for axial velocity profile only). In this Lab, we will do validation for pressure coefficient only, so, leave “Monitor location” as it was. The locations for the pressure coefficient have been hard coded in the software so you don’t need to specify them by yourself.4. ExercisesVerification and Validation of Turbulent Flow around aClark-Y Airfoil 58:160 Intermediate Mechanics of Fluids CFD LAB 2By Tao Xing and Fred SternIIHR-Hydroscience & EngineeringThe University of IowaC. Maxwell Stanley Hydraulics LaboratoryIowa City, IA 52242-15851. Purpose The Purpose of CFD Lab 2 is to simulate turbulent airfoil flows following “CFD process” by an interactive step-by-step approach and conduct verifications using CFD Educational Interface (FlowLab1.2). Students will have “hands-on” experiences using FlowLab to conduct verification and validation for lift coefficient and pressure coefficient distributions, including effect of numerical scheme. Students will manually generate the “O” type and “C” type meshes and investigate the effect of domain size and effect of angle of attack on simulation results. Students will analyze the differences between CFD and EFD, analyze possible source of errors, and present results in the CFD Lab report.1Flow Chart for ISTUE Teaching Module for Airfoil Flow (red color illustrates the options you will usein CFD Lab 2)2. Simulation DesignThe problem to be solved is that of turbulent flows around a Clark-Y airfoil. Reynolds number is143,000 based on the inlet velocity and airfoil chord length. The following figures show theillustrations for “C” type and “O” type meshes. (Note: the figures are not in the exact scale as the truesize of the domain and airfoil, as you will see in FlowLab). 2GeometryPost-processingReportPhysicsMeshContoursVectorsStreamlinesSolveIterationsConver-gent.LimitPrecisionsSingleDoubleNumerical Schemes1st order2nd orderQUICKSteady/Unsteady?CoarseMediumFineAutomaticManualStructuredUnstruct-ured BoundaryConditionsFlow PropertiesViscousModelsOne Eq.Two Eq.Density and viscosityLaminarTurbulentInviscidSAk-ek-wHeat Transfer?Incompress-ible?InitialConditionsClarkyNACA12LS(1) 0417Import ProfileChord lengthAngle of attackSelect domainSelect geometryWall shear stressSkin friction FactorXY plotsVerification and validationCoefficient of liftCoefficient of dragResidualsPressure coef. Distri.Shear stress Distri.Airfoil Y plusIn CFD Lab2, Boundary conditions for “C” type of meshes will be “inlet”, “outlet”, “symmetry”, and“airfoil”, as described later. Boundary conditions for “O” type of meshes will be “inlet”, “outlet”, and“airfoil”. Uniform flow was specified at inlet. For outlet, zero gradients are fixed for all velocities andpressure is constant. No-slip boundary condition will be used on the “airfoil”. Symmetric boundarycondition will be applied on the “symmetry”. All EFD data for turbulent airfoil flow in this Lab can be downloaded from class website.3. CFD ProcessStep 1: (Geometry) 1. Select Geometry: Clark-Y2. Chord length (0.3048 m)3. Angle of attack (0 or 6, refer to exercises for details)4. Circle Radius (5 meters except for exercise 1, where effect of domain size is studied)5. Radius (Rc) for “C” mesh (5 meters)6. Down stream length (Lo) for “C” mesh (12 meters). Click <<Create>>, after you see the airfoil geometry created in the graphic window, click <<Next>>.Step 2: (Physics)3(1). With or without Heat Transfer?No thermal effects are considered in this lab, switch the <<Heat Transfer >> button OFF, which is thedefault setup.(2). Incompressible or compressibleChoose “Incompressible”, which is the default setup.(3). Flow PropertiesUse the values shown in the above figure. Input the values and click <<OK>>.(4). Viscous Model4Choose turbulent model (k-e).(5). Boundary ConditionsAt “Inlet”, we use constant pressure and fix the velocity to 7.04m/s for turbulent airfoil flow. Usedefault values for “k” and “e”.At “Outlet”, FlowLab uses magnitude for pressure and zero gradients for axial and radial velocities.Input “0” for the Gauge pressure and click <<OK>>.On “Airfoil”, if flow is turbulent, FlowLab uses no-slip boundary conditions for velocities and zero-pressure gradient. Turbulent quantities k and e are also specified to be zero. Read all the values andclick <<OK>>.For “C” type mesh, there is one additional boundary condition, i.e., “Symmetry”. 5(6). Initial ConditionsUse the default setup for initial conditions.After specifying all the above parameters, click <<Compute>> button and FlowLab will automaticallycalculate the Reynolds number based on the inlet velocity and the airfoil chord length you specified. Click <<Next>>. This takes you to the next step, “Mesh”. Step 3: (Mesh)For CFD Lab 2, “Structured” meshes will be generated using either “Automatic” or “Manual”generations (see exercises at the end of this document for details). For “Automatic” generation, justchoose the mesh density: “coarse”, “medium” or “fine”, and click <<Create>>, FlowLab willautomatically create the mesh you required. For manually generation, you should first choose the“Manual” button, and then the following panel will be shown:61. “O” mesh generation: to generate an “O” type mesh, you need to specify the number of intervals and the first length in grid spacing for NA1, NA2, NA3 and NA4, which are the four curves that form the airfoil geometry. Then choose the number of intervals and the grid spacing near airfoil forthe edge NC1, which lays from the airfoil surface to the far-field. Finally choose “Uniform” distribution for NF1, NF2, NF3, and NF4, which are the four curves that form the far field circumference. Click <<Create>> after you input the parameters for each edge and then click <<Create>> in the mesh step window to generate the whole mesh.2. “C” mesh generation: to generate a “C” type mesh, you need to specify “NA1”, “NA2”, “NA3”, “RC”, “Symmetry”, and “inlet”. For details on
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