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Wind tunnel flow simulation boundary condition issue

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Old   October 21, 2021, 08:27
Default Wind tunnel flow simulation boundary condition issue
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charan
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Hi everybody

I am actually try to simulate WIND TUNNEL flow . the following are the inlet and outlet conditions:
Inlet
static pressure: 90419 Pa
static temp: 296.97 k
velocity: 2.374 m/s
Outlet
static pressure : 90057 Pa
static temp: 295.75 k
Velocity: 26.23 m/s
Density: 1.0609 (constant throughout the tunnel)
Viscosity : 1.83*10^-5 N.s/m^2 (constant throughout the tunnel)

I have been facing following issues
1. as the flow regime is in incompressible, i started with INC_RANS, where i used (velocity inlet & pressure outlet), (pressure inlet & pressure outlet) both has diverged.

2. i moved onto compressible solver where i took total condition at inlet & static back pressure at outlet. After solving the pressure is measure at the outlet where it is 89999 Pa instead of 90057 Pa. velocity at inlet : 3.85 m/s ( actual:2.374 m/s). velocity at outlet: 45.11 m/s (actual: 26.23 m/s ).

3. Pressure, velocity, temperature of inlet & outlet are different from the one which where imposed on them.

4. a change in initializing values ( freestream values) are also influencing the boundary condition parameters.

5. The solution is not stabilizing.

It would very helpful, if you can solve any of my issues. i am attaching my cfg file along with this for reference.


%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% %
% SU2 configuration file %
% Case description: ALFA WTM %
% Author: CHARAN PATTABHI %
% Date: 10.12.2021 %
% File Version 7.1.1 "Blackbird" %
% %
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

% ------------- DIRECT, ADJOINT, AND LINEARIZED PROBLEM DEFINITION ------------%
%
% Physical governing equations (EULER, NAVIER_STOKES,
% WAVE_EQUATION, HEAT_EQUATION, FEM_ELASTICITY,
% POISSON_EQUATION)
SOLVER= RANS
%
% Specify turbulence model (NONE, SA, SA_NEG, SST, SA_E, SA_COMP, SA_E_COMP, SST_SUST)
KIND_TURB_MODEL= SST
%
% Transition model (NONE, BC)
% KIND_TRANS_MODEL= NONE
%
% Mathematical problem (DIRECT, CONTINUOUS_ADJOINT)
MATH_PROBLEM= DIRECT
%
% Restart solution (NO, YES)
RESTART_SOL= NO
%
SYSTEM_MEASUREMENTS= SI
%
%-------------------- COMPRESSIBLE FREE-STREAM DEFINITION --------------------%
%
% Mach number (non-dimensional, based on the free-stream values)
MACH_NUMBER= 0.098
%
% Angle of attack (degrees, only for compressible flows)
AOA= 0
%
% Side-slip angle (degrees, only for compressible flows)
SIDESLIP_ANGLE= 0.0
%
% Init option to choose between Reynolds (default) or thermodynamics quantities
% for initializing the solution (REYNOLDS, TD_CONDITIONS)
% INIT_OPTION= TD_CONDITIONS
% Free-stream option to choose between density and temperature (default) for
% initializing the solution (TEMPERATURE_FS, DENSITY_FS)
% FREESTREAM_OPTION= TEMPERATURE_FS
%
% Free-stream pressure (101325.0 N/m^2, 2116.216 psf by default)
FREESTREAM_PRESSURE= 89808
% Free-stream temperature (288.15 K by default)
FREESTREAM_TEMPERATURE= 294.93

%
% Reynolds number (non-dimensional, based on the free-stream values)
REYNOLDS_NUMBER= 209741.73
%
% Reynolds length (1 m by default)
REYNOLDS_LENGTH= 0.1064
%^
% Free-stream turbulence intensity
FREESTREAM_TURBULENCEINTENSITY= 0.015
%
% Free-stream ratio between turbulent and laminar viscosity
FREESTREAM_TURB2LAMVISCRATIO= 10.0
%
% --------------------------- VISCOSITY MODEL ---------------------------------%
%
% Viscosity model (SUTHERLAND, CONSTANT_VISCOSITY).
VISCOSITY_MODEL= CONSTANT_VISCOSITY
%
% Molecular Viscosity that would be constant (1.716E-5 by default)
MU_CONSTANT= 1.830e-05

% ---- NONEQUILIBRIUM GAS, IDEAL GAS, POLYTROPIC, VAN DER WAALS AND PENG ROBINSON CONSTANTS -------%
%
% Fluid model (STANDARD_AIR, IDEAL_GAS, VW_GAS, PR_GAS,
% CONSTANT_DENSITY, INC_IDEAL_GAS, INC_IDEAL_GAS_POLY, MUTATIONPP, SU2_NONEQ)
FLUID_MODEL= STANDARD_AIR
%
% Ratio of specific heats (1.4 default and the value is hardcoded
% for the model STANDARD_AIR, compressible only)
GAMMA_VALUE= 1.4
%
% Specific gas constant (287.058 J/kg*K default and this value is hardcoded
% for the model STANDARD_AIR, compressible only)
GAS_CONSTANT= 287.058
%
%
%
% ---------------------- REFERENCE VALUE DEFINITION ---------------------------%
%
% Reference origin for moment computation
REF_ORIGIN_MOMENT_X = 0.8425
REF_ORIGIN_MOMENT_Y = 0.00
REF_ORIGIN_MOMENT_Z = 0.012
%
% Reference length for pitching, rolling, and yawing non-dimensional moment
REF_LENGTH= 0.1064
%
% Reference area for force coefficients (0 implies automatic calculation)
REF_AREA= 0.226

% -------------------- BOUNDARY CONDITION DEFINITION --------------------------%
%
% Navier-Stokes wall boundary marker(s) (NONE = no marker)
MARKER_HEATFLUX= ( AAA,0.0,AFTBODY,0.0,BULKHEAD,0.0,COWL_1,0.0,COWL_2 ,0.0,FUSE,0.0,HT,0.0,HT-HINGE,0.0,NOSE,0.0,STING,0.0,VT,0.0,VT-HINGE,0.0,WING,0.0,WING-HINGE,0.0 )
%
% Inlet boundary type (TOTAL_CONDITIONS, MASS_FLOW)
INLET_TYPE= TOTAL_CONDITIONS
%
% Inlet boundary marker(s) (NONE = no marker)
% % Inlet boundary marker(s) with the following formats (NONE = no marker)
% Total Conditions: (inlet marker, total temp, total pressure, flow_direction_x,
% flow_direction_y, flow_direction_z, ... ) where flow_direction is
% a unit vector.
% Mass Flow: (inlet marker, density, velocity magnitude, flow_direction_x,
% flow_direction_y, flow_direction_z, ... ) where flow_direction is
% a unit vector.
% Inc. Velocity: (inlet marker, temperature, velocity magnitude, flow_direction_x,
% flow_direction_y, flow_direction_z, ... ) where flow_direction is
% a unit vector.
% Inc. Pressure: (inlet marker, temperature, total pressure, flow_direction_x,
% flow_direction_y, flow_direction_z, ... ) where flow_direction is
% a unit vector.
MARKER_INLET= ( A-IINLET, 296.97, 90422.12, 1.0, 0.0, 0.0 )
%
% Outlet boundary marker(s) (NONE = no marker)
% Compressible: ( outlet marker, back pressure (static thermodynamic), ... )
% Inc. Pressure: ( outlet marker, back pressure (static gauge in Pa), ... )
% Inc. Mass Flow: ( outlet marker, mass flow target (kg/s), ... )
MARKER_OUTLET= ( AA-OUTLET, 90057.00 )
%
% Symmetry boundary marker(s) (NONE = no marker)
% MARKER_SYM= ( symmetry )
%
% Marker(s) of the surface to be plotted or designed
MARKER_PLOTTING= ( AFTBODY,BULKHEAD,COWL_1,COWL_2,FUSE,HT,HT-HINGE,NOSE,STING,VT,VT-HINGE,WING,WING-HINGE )
%
% Marker(s) of the surface where the functional (Cd, Cl, etc.) will be evaluated
MARKER_MONITORING= ( AFTBODY,BULKHEAD,COWL_1,COWL_2,FUSE,HT,HT-HINGE,NOSE,STING,VT,VT-HINGE,WING,WING-HINGE )

% Marker(s) of the surface that is going to be analyzed in detail (massflow, average pressure, distortion, etc)
MARKER_ANALYZE = ( A-IINLET, AA-OUTLET )

% Method to compute the average value in MARKER_ANALYZE (AREA, MASSFLUX).
MARKER_ANALYZE_AVERAGE = MASSFLUX

% ------------- COMMON PARAMETERS DEFINING THE NUMERICAL METHOD ---------------%
%
% Numerical method for spatial gradients (GREEN_GAUSS, LEAST_SQUARES,
% WEIGHTED_LEAST_SQUARES)
NUM_METHOD_GRAD= WEIGHTED_LEAST_SQUARES
%
% Courant-Friedrichs-Lewy condition of the finest grid
CFL_NUMBER= 10
%
% Adaptive CFL number (NO, YES)
CFL_ADAPT= NO
%
% Parameters of the adaptive CFL number (factor down, factor up, CFL min value,
% CFL max value )
CFL_ADAPT_PARAM= ( 0.1, 2.0, 100.0, 1e3 )
%
% Runge-Kutta alpha coefficients
RK_ALPHA_COEFF= ( 0.66667, 0.66667, 1.000000 )
%
% Number of total iterations
ITER= 600

% ------------------------ LINEAR SOLVER DEFINITION ---------------------------%
%
% Linear solver for implicit formulations (BCGSTAB, FGMRES)
LINEAR_SOLVER= FGMRES
%
% Preconditioner of the Krylov linear solver (JACOBI, LINELET, LU_SGS)
LINEAR_SOLVER_PREC= LU_SGS
%
% Linael solver ILU preconditioner fill-in level (0 by default)
LINEAR_SOLVER_ILU_FILL_IN= 0
%
% Minimum error of the linear solver for implicit formulations
LINEAR_SOLVER_ERROR= 1E-8
%
% Max number of iterations of the linear solver for the implicit formulation
LINEAR_SOLVER_ITER= 10

% ----------------------- SLOPE LIMITER DEFINITION ----------------------------%
%
% Coefficient for the limiter
VENKAT_LIMITER_COEFF=0.1
%
% Coefficient for the sharp edges limiter
ADJ_SHARP_LIMITER_COEFF= 3.0
%
% Reference coefficient (sensitivity) for detecting sharp edges.
REF_SHARP_EDGES= 3.0
%
% Remove sharp edges from the sensitivity evaluation (NO, YES)
SENS_REMOVE_SHARP= NO

% -------------------------- MULTIGRID PARAMETERS -----------------------------%
%
% Multi-Grid Levels (0 = no multi-grid)
MGLEVEL= 0
%
% Multi-grid cycle (V_CYCLE, W_CYCLE, FULLMG_CYCLE)
MGCYCLE= V_CYCLE
%
% Multi-grid pre-smoothing level
MG_PRE_SMOOTH= ( 1, 1, 1, 1 )
%
% Multi-grid post-smoothing level
MG_POST_SMOOTH= ( 0, 0, 0, 0 )
%
% Jacobi implicit smoothing of the correction
MG_CORRECTION_SMOOTH= ( 0, 0, 0, 0 )
%
% Damping factor for the residual restriction
MG_DAMP_RESTRICTION= 0.8
%
% Damping factor for the correction prolongation
MG_DAMP_PROLONGATION= 0.8

% -------------------- FLOW NUMERICAL METHOD DEFINITION -----------------------%
%
% Convective numerical method (JST, LAX-FRIEDRICH, CUSP, ROE, AUSM, HLLC,
% TURKEL_PREC, MSW)
CONV_NUM_METHOD_FLOW= ROE
%
% Monotonic Upwind Scheme for Conservation Laws (TVD) in the flow equations.
% Required for 2nd order upwind schemes (NO, YES)
MUSCL_FLOW= YES
%
% Slope limiter (NONE, VENKATAKRISHNAN, VENKATAKRISHNAN_WANG,
% BARTH_JESPERSEN, VAN_ALBADA_EDGE)
SLOPE_LIMITER_FLOW= NONE
%
% Time discretization (RUNGE-KUTTA_EXPLICIT, EULER_IMPLICIT, EULER_EXPLICIT)
TIME_DISCRE_FLOW= EULER_IMPLICIT

% -------------------- TURBULENT NUMERICAL METHOD DEFINITION ------------------%
%
% Convective numerical method (SCALAR_UPWIND)
CONV_NUM_METHOD_TURB= SCALAR_UPWIND
%
% Monotonic Upwind Scheme for Conservation Laws (TVD) in the turbulence equations.
% Required for 2nd order upwind schemes (NO, YES)
MUSCL_TURB= NO
%
% Slope limiter (VENKATAKRISHNAN, MINMOD)
SLOPE_LIMITER_TURB= VENKATAKRISHNAN
%
% Time discretization (EULER_IMPLICIT)
TIME_DISCRE_TURB= EULER_IMPLICIT

% --------------------------- CONVERGENCE PARAMETERS --------------------------%
%
% Convergence criteria (CAUCHY, RESIDUAL)
CONV_FIELD= RMS_DENSITY
%
% Min value of the residual (log10 of the residual)
CONV_RESIDUAL_MINVAL= -6
%
% Start convergence criteria at iteration number
CONV_STARTITER= 10
%
% Number of elements to apply the criteria
CONV_CAUCHY_ELEMS= 100
%
% Epsilon to control the series convergence
CONV_CAUCHY_EPS= 1E-6
%

% ------------------------- SCREEN/HISTORY VOLUME OUTPUT --------------------------%
%
% Screen output
SCREEN_OUTPUT= (INNER_ITER, WALL_TIME, RMS_DENSITY, RMS_PRESSURE, LIFT, DRAG)
%
% History output groups (use 'SU2_CFD -d <config_file>' to view list of available fields)
HISTORY_OUTPUT= (ITER, WALL_TIME,AERO_COEFF, FLOW_COEFF, RMS_RES )
%
% Volume output fields/groups (use 'SU2_CFD -d <config_file>' to view list of available fields)
VOLUME_OUTPUT= (COORDINATES, SOLUTION, PRIMITIVE, RESIDUAL)
%
% Writing frequency for screen output
SCREEN_WRT_FREQ_INNER= 1
%
SCREEN_WRT_FREQ_OUTER= 1
%
SCREEN_WRT_FREQ_TIME= 1
%
% Writing frequency for history output
HISTORY_WRT_FREQ_INNER= 1
%
HISTORY_WRT_FREQ_OUTER= 1
%
HISTORY_WRT_FREQ_TIME= 1
%
% Writing frequency for volume/surface output
OUTPUT_WRT_FREQ= 10
%
% ------------------------- INPUT/OUTPUT INFORMATION --------------------------%
%
% Mesh input file
MESH_FILENAME= a_10_su2.cgns
%
% Mesh input file format (SU2, CGNS, NETCDF_ASCII)
MESH_FORMAT= CGNS
%
% Mesh output file
MESH_OUT_FILENAME= mesh_out.su2
%
% Restart flow input file
SOLUTION_FILENAME= restart_flow.dat
%
% Restart adjoint input file
SOLUTION_ADJ_FILENAME= solution_adj.dat
%
% Output file format (PARAVIEW, TECPLOT, SLT)
TABULAR_FORMAT= CSV
%
% Files to output
% Possible formats : (TECPLOT, TECPLOT_BINARY, SURFACE_TECPLOT,
% SURFACE_TECPLOT_BINARY, CSV, SURFACE_CSV, PARAVIEW, PARAVIEW_BINARY, SURFACE_PARAVIEW,
% SURFACE_PARAVIEW_BINARY, MESH, RESTART_BINARY, RESTART_ASCII, CGNS, STL)
% default : (RESTART, PARAVIEW, SURFACE_PARAVIEW)
OUTPUT_FILES= (RESTART, PARAVIEW, SURFACE_PARAVIEW)
%
% Output file convergence history (w/o extension)
CONV_FILENAME= history
%
WRT_FORCES_BREAKDOWN=YES
BREAKDOWN_FILENAME= forces_breakdown.dat
%
% Output file restart flow
RESTART_FILENAME= restart_flow.dat
%
%
% Output file flow (w/o extension) variables
VOLUME_FILENAME= flow
%
%
%
% Output file surface flow coefficient (w/o extension)
SURFACE_FILENAME= surface_flow
%
%
%
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