# wrong SU2 calculation for lift and drag coefficient for NAC4421

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 LinkBack Thread Tools Search this Thread Display Modes May 28, 2014, 13:55 wrong SU2 calculation for lift and drag coefficient of NACA4421 #1 Senior Member   Join Date: Jun 2011 Posts: 163 Rep Power: 11 Hi All I have generated a mesh for NACA 4412 airfoil. the mesh has a good quality and it has inflation near the airfoil. I have simulated the flow around this airfoil at Ma=0.3. the experimental vale of the lift and drag coefficient are Cl=0.4 CD=0.008 the Fluent and OpenFoam give similar values for lift and drag but Su2 results are very different to experimental results(CL=0.091 and Cd=0.0169). the SU2 setting are attached and if you need the mesh file, please give me your email. I will be so thankful if you can help me Best Regards SU2 settings: Code: ```% ------------- DIRECT, ADJOINT, AND LINEARIZED PROBLEM DEFINITION ------------% % % Physical governing equations (POTENTIAL_FLOW, EULER, NAVIER_STOKES, % MULTI_SPECIES_NAVIER_STOKES, TWO_PHASE_FLOW, % COMBUSTION) PHYSICAL_PROBLEM= NAVIER_STOKES % % Mathematical problem (DIRECT, ADJOINT, LINEARIZED, ONE_SHOT_ADJOINT) MATH_PROBLEM= DIRECT % % If Navier-Stokes, kind of turbulent model (NONE, SA) KIND_TURB_MODEL= SA % % Restart solution (NO, YES) RESTART_SOL= NO % % Console output (VERBOSE, CONCISE, QUIET) CONSOLE= CONCISE % ----------- COMPRESSIBLE AND INCOMPRESSIBLE FREE-STREAM DEFINITION ----------% % % Mach number (non-dimensional, based on the free-stream values) MACH_NUMBER= 0.3 % % Angle of attack (degrees) AoA=0.0 % % Free-stream pressure (101325.0 N/m^2 by default, only Euler flows) FREESTREAM_PRESSURE= 101325.0 % % Free-stream temperature (273.15 K by default) FREESTREAM_TEMPERATURE= 273.15 % % Reynolds number (non-dimensional, based on the free-stream values) REYNOLDS_NUMBER= 7.16E6 % % Reynolds length (1 m by default) REYNOLDS_LENGTH= 1.0 % % Free-stream Turbulence Intensity FREESTREAM_TURBULENCEINTENSITY = 0.01 % % Free-stream Turbulent to Laminar viscosity ratio FREESTREAM_TURB2LAMVISCRATIO = 2.0 % -------------- COMPRESSIBLE AND INCOMPRESSIBLE FLUID CONSTANTS --------------% % % Ratio of specific heats (1.4 (air), only for compressible flows) GAMMA_VALUE= 1.4 % % Specific gas constant (287.87 J/kg*K (air), only for compressible flows) GAS_CONSTANT= 287.87 % % Laminar Prandtl number (0.72 (air), only for compressible flows) PRANDTL_LAM= 0.72 % % Turbulent Prandtl number (0.9 (air), only for compressible flows) PRANDTL_TURB= 0.9 % ---------------------- REFERENCE VALUE DEFINITION ---------------------------% % % Conversion factor for converting the grid to meters CONVERT_TO_METER= 1.0 % % Reference origin for moment computation REF_ORIGIN_MOMENT_X = 0.25 REF_ORIGIN_MOMENT_Y = 0.00 REF_ORIGIN_MOMENT_Z = 0.00 % % Reference length for pitching, rolling, and yawing non-dimensional moment REF_LENGTH_MOMENT= 1.0 % % Reference area for force coefficients (0 implies automatic calculation) REF_AREA= 1.0 % % Reference pressure (101325.0 N/m^2 by default) REF_PRESSURE= 1.0 % % Reference temperature (273.15 K by default) REF_TEMPERATURE= 1.0 % % Reference density (1.2886 Kg/m^3 (air), 998.2 Kg/m^3 (water)) REF_DENSITY= 1.0 % ----------------------- BOUNDARY CONDITION DEFINITION -----------------------% % % Marker of the Euler boundary (0 = no marker) MARKER_HEATFLUX= ( airfoil,0.0,plate,0.0 ) % % Marker of the far field (0 = no marker) MARKER_FAR= ( inlet,outlet,farfield ) % % ------------------------ SURFACES IDENTIFICATION ----------------------------% % % Marker of the surface which is going to be plotted or designed MARKER_PLOTTING= ( airfoil,plate ) % % Marker of the surface where the functional (Cd, Cl, etc.) will be evaluated MARKER_MONITORING= ( airfoil,plate ) % % Marker(s) of the surface where obj. func. (design problem) will be evaluated MARKER_DESIGNING = ( airfoil ) % % ------------- COMMON PARAMETERS TO DEFINE THE NUMERICAL METHOD --------------% % % Numerical method for spatial gradients (GREEN_GAUSS, WEIGHTED_LEAST_SQUARES) NUM_METHOD_GRAD= WEIGHTED_LEAST_SQUARES % % Courant-Friedrichs-Lewy condition of the finest grid CFL_NUMBER= 2.0 % % CFL ramp (factor, number of iterations, CFL limit) CFL_RAMP= ( 1., 100, 4.0 ) % % Runge-Kutta alpha coefficients RK_ALPHA_COEFF= ( 0.66667, 0.66667, 1.000000 ) % % Number of total iterations EXT_ITER= 7000 % % ------------------------ LINEAR SOLVER DEFINITION ---------------------------% % % Linear solver for the implicit (or discrete adjoint) formulation (BCGSTAB, FGMRES) LINEAR_SOLVER= FGMRES % % Preconditioner of the Krylov linear solver (JACOBI, LINELET, LU_SGS) %LINEAR_SOLVER_PREC= LU_SGS % % Min error of the linear solver for the implicit formulation LINEAR_SOLVER_ERROR= 1E-6 % % Max number of iterations of the linear solver for the implicit formulation LINEAR_SOLVER_ITER= 30 % % Relaxation coefficient %LINEAR_SOLVER_RELAX= 1.0 % -------------------------- MULTIGRID PARAMETERS -----------------------------% % % Full Multigrid (NO, YES) FULLMG= NO % % Start up iterations using the fine grid START_UP_ITER= 0 % % Multi-Grid Levels (0 = no multi-grid) MGLEVEL= 2 % % Multi-Grid Cycle (0 = V cycle, 1 = W Cycle) MGCYCLE= 1 % % Reduction factor of the CFL coefficient on the coarse levels MG_CFL_REDUCTION= 0.9 % % Maximum number of children in the agglomeration stage MAX_CHILDREN= 250 % % Maximum length of an agglomerated element (compared with the domain) MAX_DIMENSION= 0.1 % % Multi-Grid PreSmoothing Level MG_PRE_SMOOTH= ( 1, 2, 3, 3 ) % % Multi-Grid PostSmoothing Level MG_POST_SMOOTH= ( 1, 2, 3, 3 ) % % Jacobi implicit smoothing of the correction MG_CORRECTION_SMOOTH= ( 1, 1, 1, 1 ) % % Damping factor for the residual restriction MG_DAMP_RESTRICTION= 0.9 % % Damping factor for the correction prolongation MG_DAMP_PROLONGATION= 0.9 % --------------------- FLOW NUMERICAL METHOD DEFINITION ----------------------% % % Convective numerical method (JST, LAX-FRIEDRICH, ROE-1ST_ORDER, % ROE-2ND_ORDER) % CONV_NUM_METHOD_FLOW= JST % % Slope limiter (NONE, VENKATAKRISHNAN) SLOPE_LIMITER_FLOW= NONE % % Coefficient for the limiter (smooth regions) %LIMITER_COEFF= 0.1 % % 1st, 2nd and 4th order artificial dissipation coefficients AD_COEFF_FLOW= ( 0.15, 0.5, 0.02 ) % % Viscous numerical method (AVG_GRAD, AVG_GRAD_CORRECTED, GALERKIN) VISC_NUM_METHOD_FLOW= AVG_GRAD_CORRECTED % % Source term numerical method (PIECEWISE_CONSTANT) SOUR_NUM_METHOD_FLOW= PIECEWISE_CONSTANT % % Time discretization (RUNGE-KUTTA_EXPLICIT, EULER_IMPLICIT, EULER_EXPLICIT) TIME_DISCRE_FLOW= EULER_IMPLICIT % -------------------- TURBULENT NUMERICAL METHOD DEFINITION ------------------% % % Convective numerical method (SCALAR_UPWIND-1ST_ORDER, % SCALAR_UPWIND-2ND_ORDER) CONV_NUM_METHOD_TURB= SCALAR_UPWIND-1ST_ORDER % % Slope limiter (NONE, VENKATAKRISHNAN) SLOPE_LIMITER_TURB= NONE % % Viscous numerical method (AVG_GRAD, AVG_GRAD_CORRECTED) VISC_NUM_METHOD_TURB= AVG_GRAD_CORRECTED % % Source term numerical method (PIECEWISE_CONSTANT) SOUR_NUM_METHOD_TURB= PIECEWISE_CONSTANT % % Time discretization (EULER_IMPLICIT) TIME_DISCRE_TURB= EULER_IMPLICIT % ---------------- ADJOINT-FLOW NUMERICAL METHOD DEFINITION -------------------% % Adjoint problem boundary condition (DRAG, LIFT, SIDEFORCE, MOMENT_X, % MOMENT_Y, MOMENT_Z, EFFICIENCY, % EQUIVALENT_AREA, NEARFIELD_PRESSURE, % FORCE_X, FORCE_Y, FORCE_Z, THRUST, % TORQUE, FREE_SURFACE) ADJ_OBJFUNC= DRAG % % Convective numerical method (JST, LAX-FRIEDRICH, ROE-1ST_ORDER, % ROE-2ND_ORDER) CONV_NUM_METHOD_ADJ= JST % % Slope limiter (NONE, VENKATAKRISHNAN, SHARP_EDGES) SLOPE_LIMITER_ADJFLOW= SHARP_EDGES % % Coefficient for the sharp edges limiter SHARP_EDGES_COEFF= 3.0 % % 1st, 2nd, and 4th order artificial dissipation coefficients AD_COEFF_ADJ= ( 0.15, 0.0, 0.01 ) % % Reduction factor of the CFL coefficient in the adjoint problem ADJ_CFL_REDUCTION= 0.9 % % Limit value for the adjoint variable ADJ_LIMIT= 1E6 % % Remove sharp edges from the sensitivity evaluation (NO, YES) SENS_REMOVE_SHARP= YES % % Viscous numerical method (AVG_GRAD, AVG_GRAD_CORRECTED, GALERKIN) VISC_NUM_METHOD_ADJ= AVG_GRAD_CORRECTED % % Source term numerical method (PIECEWISE_CONSTANT) SOUR_NUM_METHOD_ADJ= PIECEWISE_CONSTANT % % Time discretization (RUNGE-KUTTA_EXPLICIT, EULER_IMPLICIT) TIME_DISCRE_ADJ= EULER_IMPLICIT % % Adjoint frozen viscosity (NO, YES) FROZEN_VISC= YES % % --------------------------- PARTITIONING STRATEGY ---------------------------% % Write a paraview file for each partition (NO, YES) VISUALIZE_PART= NO % ----------------------- GEOMETRY EVALUATION PARAMETERS ----------------------% % % Geometrical evaluation mode (FUNCTION, GRADIENT) GEO_MODE= FUNCTION % ------------------------- GRID ADAPTATION STRATEGY --------------------------% % % Percentage of new elements (% of the original number of elements) NEW_ELEMS= 15 % % Kind of grid adaptation (NONE, FULL, FULL_FLOW, GRAD_FLOW, FULL_ADJOINT, % GRAD_ADJOINT, GRAD_FLOW_ADJ, ROBUST, % FULL_LINEAR, COMPUTABLE, COMPUTABLE_ROBUST, % REMAINING, WAKE, HORIZONTAL_PLANE) KIND_ADAPT= FULL_FLOW % % Scale factor for the dual volume DUALVOL_POWER= 0.5 % % Use analytical definition for surfaces (NONE, NACA0012_airfoil, BIPARABOLIC, % NACA4412_airfoil, CYLINDER) ANALYTICAL_SURFDEF= NACA0012_airfoil % % Before each computation do an implicit smoothing of the nodes coord (NO, YES) SMOOTH_GEOMETRY= YES % ------------------------ GRID DEFORMATION PARAMETERS ------------------------% % Kind of deformation (NO_DEFORMATION, HICKS_HENNE, HICKS_HENNE_NORMAL, PARABOLIC, % HICKS_HENNE_SHOCK, NACA_4DIGITS, DISPLACEMENT, ROTATION, % FFD_CONTROL_POINT, FFD_DIHEDRAL_ANGLE, FFD_TWIST_ANGLE, % FFD_ROTATION) DV_KIND= HICKS_HENNE % % Marker of the surface in which we are going apply the shape deformation DV_MARKER= ( airfoil ) % % Parameters of the shape deformation % - HICKS_HENNE_FAMILY ( Lower(0)/Upper(1) side, x_Loc ) % - NACA_4DIGITS ( 1st digit, 2nd digit, 3rd and 4th digit ) % - PARABOLIC ( 1st digit, 2nd and 3rd digit ) % - DISPLACEMENT ( x_Disp, y_Disp, z_Disp ) % - ROTATION ( x_Orig, y_Orig, z_Orig, x_End, y_End, z_End ) DV_PARAM= ( 1, 0.5 ) % % Old value of the deformation for incremental deformations DV_VALUE= 0.05 % % Grid deformation technique (SPRING, TORSIONAL_SPRING, ALGEBRAIC) GRID_DEFORM_METHOD= SPRING % % Visualize the deformation (NO, YES) VISUALIZE_DEFORMATION= YES % --------------------------- CONVERGENCE PARAMETERS --------------------------% % Convergence criteria (CAUCHY, RESIDUAL) % CONV_CRITERIA= RESIDUAL % % Residual reduction (order of magnitude with respect to the initial value) RESIDUAL_REDUCTION= 8 % % Min value of the residual (log10 of the residual) RESIDUAL_MINVAL= -8.4 % % Start Cauchy criteria at iteration number STARTCONV_ITER= 10 % % Number of elements to apply the criteria CAUCHY_ELEMS= 100 % % Epsilon to control the series convergence CAUCHY_EPS= 1E-6 % % Function to apply the criteria (LIFT, DRAG, SENS_GEOMETRY, SENS_MACH, % DELTA_LIFT, DELTA_DRAG) CAUCHY_FUNC_FLOW= DRAG CAUCHY_FUNC_ADJ= SENS_GEOMETRY % % Epsilon for full multigrid method evaluation FULLMG_CAUCHY_EPS= 1E-3 % ------------------------- INPUT/OUTPUT INFORMATION --------------------------% % Mesh input file MESH_FILENAME= NACA4421_clean_inf_34.su2 % % Mesh input file format (SU2, CGNS, NETCDF_ASCII) MESH_FORMAT= SU2 % % Convert a CGNS mesh to SU2 format (YES, NO) CGNS_TO_SU2= NO % % Mesh output file MESH_OUT_FILENAME= mesh_out.su2 % % Restart flow input file SOLUTION_FLOW_FILENAME= solution_flow.dat % % Restart adjoint input file SOLUTION_ADJ_FILENAME= solution_adj.dat % % Output file format (PARAVIEW, TECPLOT) OUTPUT_FORMAT= PARAVIEW % % Output file convergence history (w/o extension) CONV_FILENAME= history % % Output file restart flow RESTART_FLOW_FILENAME= restart_flow.dat % % Output file restart adjoint RESTART_ADJ_FILENAME= restart_adj.dat % % Output file flow (w/o extension) variables VOLUME_FLOW_FILENAME= flow % % Output file adjoint (w/o extension) variables VOLUME_ADJ_FILENAME= adjoint % % Output Objective function gradient (using continuous adjoint) GRAD_OBJFUNC_FILENAME= of_grad.dat % % Output file surface flow coefficient (w/o extension) SURFACE_FLOW_FILENAME= surface_flow % % Output file surface adjoint coefficient (w/o extension) SURFACE_ADJ_FILENAME= surface_adjoint % % Writing solution file frequency WRT_SOL_FREQ= 500 % % Writing solution file frequency for physical time steps (dual time) WRT_SOL_FREQ_DUALTIME= 1 % % Writing convergence history frequency WRT_CON_FREQ= 10 % % Writing convergence history frequency (dual time, only written to screen) WRT_CON_FREQ_DUALTIME= 10 % % Writing linear solver history frequency WRT_LIN_CON_FREQ= 1 % % Output rind layers in the solution files WRT_HALO= NO % --------------------- OPTIMAL SHAPE DESIGN DEFINITION -----------------------% % Available flow based objective functions or constraint functions % DRAG, LIFT, SIDEFORCE, EFFICIENCY, % FORCE_X, FORCE_Y, FORCE_Z, % MOMENT_X, MOMENT_Y, MOMENT_Z, % THRUST, TORQUE, FIGURE_OF_MERIT, % EQUIVALENT_AREA, NEARFIELD_PRESSURE, % FREE_SURFACE % % Available geometrical based objective functions or constraint functions % MAX_THICKNESS, 1/4_THICKNESS, 1/2_THICKNESS, 3/4_THICKNESS, AREA, AOA, CHORD, % MAX_THICKNESS_SEC1, MAX_THICKNESS_SEC2, MAX_THICKNESS_SEC3, MAX_THICKNESS_SEC4, MAX_THICKNESS_SEC5, % 1/4_THICKNESS_SEC1, 1/4_THICKNESS_SEC2, 1/4_THICKNESS_SEC3, 1/4_THICKNESS_SEC4, 1/4_THICKNESS_SEC5, % 1/2_THICKNESS_SEC1, 1/2_THICKNESS_SEC2, 1/2_THICKNESS_SEC3, 1/2_THICKNESS_SEC4, 1/2_THICKNESS_SEC5, % 3/4_THICKNESS_SEC1, 3/4_THICKNESS_SEC2, 3/4_THICKNESS_SEC3, 3/4_THICKNESS_SEC4, 3/4_THICKNESS_SEC5, % AREA_SEC1, AREA_SEC2, AREA_SEC3, AREA_SEC4, AREA_SEC5, % AOA_SEC1, AOA_SEC2, AOA_SEC3, AOA_SEC4, AOA_SEC5, % CHORD_SEC1, CHORD_SEC2, CHORD_SEC3, CHORD_SEC4, CHORD_SEC5 % % Available design variables % HICKS_HENNE ( 1, Scale | Mark. List | Lower(0)/Upper(1) side, x_Loc ) % COSINE_BUMP ( 2, Scale | Mark. List | Lower(0)/Upper(1) side, x_Loc, x_Size ) % SPHERICAL ( 3, Scale | Mark. List | ControlPoint_Index, Theta_Disp, R_Disp ) % NACA_4DIGITS ( 4, Scale | Mark. List | 1st digit, 2nd digit, 3rd and 4th digit ) % DISPLACEMENT ( 5, Scale | Mark. List | x_Disp, y_Disp, z_Disp ) % ROTATION ( 6, Scale | Mark. List | x_Axis, y_Axis, z_Axis, x_Turn, y_Turn, z_Turn ) % FFD_CONTROL_POINT ( 7, Scale | Mark. List | Chunk, i_Ind, j_Ind, k_Ind, x_Mov, y_Mov, z_Mov ) % FFD_DIHEDRAL_ANGLE ( 8, Scale | Mark. List | Chunk, x_Orig, y_Orig, z_Orig, x_End, y_End, z_End ) % FFD_TWIST_ANGLE ( 9, Scale | Mark. List | Chunk, x_Orig, y_Orig, z_Orig, x_End, y_End, z_End ) % FFD_ROTATION ( 10, Scale | Mark. List | Chunk, x_Orig, y_Orig, z_Orig, x_End, y_End, z_End ) % FFD_CAMBER ( 11, Scale | Mark. List | Chunk, i_Ind, j_Ind ) % FFD_THICKNESS ( 12, Scale | Mark. List | Chunk, i_Ind, j_Ind ) % FFD_VOLUME ( 13, Scale | Mark. List | Chunk, i_Ind, j_Ind ) % FOURIER ( 14, Scale | Mark. List | Lower(0)/Upper(1) side, index, cos(0)/sin(1) ) % % Optimization objective function with scaling factor % ex= Objective * Scale OPT_OBJECTIVE= DRAG * 0.01 % % Optimization constraint functions with scaling factors, separated by semicolons % ex= (Objective = Value ) * Scale, use '>','<','=' OPT_CONSTRAINT= ( MAX_THICKNESS > 0.08 ) * 0.01 % % Optimization design variables, separated by semicolons DEFINITION_DV= ( 1, 1.0 | airfoil | 0, 0.05 ); ( 1, 1.0 | airfoil | 0, 0.10 ); ( 1, 1.0 | airfoil | 0, 0.15 ); ( 1, 1.0 | airfoil | 0, 0.20 ); ( 1, 1.0 | airfoil | 0, 0.25 ); ( 1, 1.0 | airfoil | 0, 0.30 ); ( 1, 1.0 | airfoil | 0, 0.35 ); ( 1, 1.0 | airfoil | 0, 0.40 ); ( 1, 1.0 | airfoil | 0, 0.45 ); ( 1, 1.0 | airfoil | 0, 0.50 ); ( 1, 1.0 | airfoil | 0, 0.55 ); ( 1, 1.0 | airfoil | 0, 0.60 ); ( 1, 1.0 | airfoil | 0, 0.65 ); ( 1, 1.0 | airfoil | 0, 0.70 ); ( 1, 1.0 | airfoil | 0, 0.75 ); ( 1, 1.0 | airfoil | 0, 0.80 ); ( 1, 1.0 | airfoil | 0, 0.85 ); ( 1, 1.0 | airfoil | 0, 0.90 ); ( 1, 1.0 | airfoil | 0, 0.95 ); ( 1, 1.0 | airfoil | 1, 0.05 ); ( 1, 1.0 | airfoil | 1, 0.10 ); ( 1, 1.0 | airfoil | 1, 0.15 ); ( 1, 1.0 | airfoil | 1, 0.20 ); ( 1, 1.0 | airfoil | 1, 0.25 ); ( 1, 1.0 | airfoil | 1, 0.30 ); ( 1, 1.0 | airfoil | 1, 0.35 ); ( 1, 1.0 | airfoil | 1, 0.40 ); ( 1, 1.0 | airfoil | 1, 0.45 ); ( 1, 1.0 | airfoil | 1, 0.50 ); ( 1, 1.0 | airfoil | 1, 0.55 ); ( 1, 1.0 | airfoil | 1, 0.60 ); ( 1, 1.0 | airfoil | 1, 0.65 ); ( 1, 1.0 | airfoil | 1, 0.70 ); ( 1, 1.0 | airfoil | 1, 0.75 ); ( 1, 1.0 | airfoil | 1, 0.80 ); ( 1, 1.0 | airfoil | 1, 0.85 ); ( 1, 1.0 | airfoil | 1, 0.90 ); ( 1, 1.0 | airfoil | 1, 0.95 )``` Last edited by mechy; May 28, 2014 at 23:50.   May 30, 2014, 00:38 #2 Senior Member   Join Date: Jun 2011 Posts: 163 Rep Power: 11 I have used different meshes for NACA4421 but all of them gave the similar results. moreover, I have simulated the NACA2412 by SU2. the lift and drag coefficients for this airfoil are wrong, too I think there are some Bugs in the SU2 code am I right ? Best Regards   June 5, 2014, 15:01 #3 Super Moderator   Francisco Palacios Join Date: Jan 2013 Location: Long Beach, CA Posts: 404 Rep Power: 12 SU2 has been validated in different and representative test cases. Our recommendation is to use one of the grid and config files that you can find in the TestCases folder to start using the code. Actually we are implementing a wall function capability which will be available in the next release. That capability will reduce the grid requirement. Stay tuned for news, Cheers, Francisco   June 6, 2014, 17:53 #4 Super Moderator   Francisco Palacios Join Date: Jan 2013 Location: Long Beach, CA Posts: 404 Rep Power: 12 Hi, We have detected a problem in the 2D CGNS reader. If your grid was in CGNS format, please try again with the latest version of the code in the GitHub repository. https://github.com/su2code/SU2 Cheers, Francisco   June 7, 2014, 03:43 #5 Senior Member   Join Date: Jun 2011 Posts: 163 Rep Power: 11 Dear Palacios I have sent my mesh to you last week and you answered me But I can not get correct results from SU2. my mesh is not in CGNS format and if you want I can send it to you again Best Regards Yasser   June 24, 2014, 16:20 #6 Super Moderator   Thomas D. Economon Join Date: Jan 2013 Location: Stanford, CA Posts: 271 Rep Power: 11 Hi Yasser, Have you been able to resolve this issue? As Francisco mentioned, the code has now been verified and validated in detail using many well-known RANS test cases. Can you please double check that your mesh is appropriate (good stretching qualities, y+ < 1.0 everywhere near the airfoil surface), and that your configuration file settings are similar to those found in one of the RANS examples found in the test cases folder available now on GitHub? Cheers, Tom   January 5, 2017, 18:37 #7
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Peter
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 Originally Posted by economon Hi Yasser, Have you been able to resolve this issue? As Francisco mentioned, the code has now been verified and validated in detail using many well-known RANS test cases. Can you please double check that your mesh is appropriate (good stretching qualities, y+ < 1.0 everywhere near the airfoil surface), and that your configuration file settings are similar to those found in one of the RANS examples found in the test cases folder available now on GitHub? Cheers, Tom
I know this is an old thread, but I'm having this same problem. When you say y+ < 1.0 everywhere, what does that mean? The y-axis has to be less than one, or something else? I'm a beginner to CFD.

Thanks!   January 9, 2017, 05:18 #8
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 Originally Posted by APCoding I know this is an old thread, but I'm having this same problem. When you say y+ < 1.0 everywhere, what does that mean? The y-axis has to be less than one, or something else? I'm a beginner to CFD. Thanks!
Briefly y+ is the first height of your grid from the wall. To compute it you can use tools like this

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