[cucs77]

Goog Morning,

I'm trying to simulate a viscous flow around a circular cylinder (2D) but I can't get the solution to converge.

Does anyone have an idea or can explain to me how to choose and set the limiters? It's not very clear from the site how these choices are made.

In the meantime I attach the CFG file.

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% %
% SU2 configuration file %
% Case description: Viscous flow circular_cylinder %
% Author: %
% Institution: %
% Date: 2024.12.28 %
% File Version 8.1.0 "Harrier" %
% %
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

% ------------- DIRECT, ADJOINT, AND LINEARIZED PROBLEM DEFINITION ------------%
%
SOLVER= NAVIER_STOKES
KIND_TURB_MODEL= NONE
MATH_PROBLEM= DIRECT
RESTART_SOL= NO
RESTART_ITER=1
READ_BINARY_RESTART= NO
% ----------- COMPRESSIBLE AND INCOMPRESSIBLE FREE-STREAM DEFINITION ----------%
%
FLUID_MODEL= IDEAL_GAS
GAMMA_VALUE= 1.4
GAS_CONSTANT= 287.0
MACH_NUMBER= 5.0
AOA= 0.0
SIDESLIP_ANGLE= 0.0
FREESTREAM_TEMPERATURE= 136.1
FREESTREAM_PRESSURE=4.1
REYNOLDS_NUMBER= 1.8875e6
REYNOLDS_LENGTH= 2.0
% ---------------------- REFERENCE VALUE DEFINITION ---------------------------%
%
REF_ORIGIN_MOMENT_X = 0.00
REF_ORIGIN_MOMENT_Y = 0.00
REF_ORIGIN_MOMENT_Z = 0.00
REF_LENGTH= 1.0
REF_AREA= 29.0

% -------------------- BOUNDARY CONDITION DEFINITION --------------------------%
%
MARKER_HEATFLUX= ( wall, 0.0 )
MARKER_SUPERSONIC_OUTLET= ( outlet )
MARKER_SUPERSONIC_INLET=(Inlet, 136.1, 592.149, 1169.24, 0.0,0.0 )
MARKER_PLOTTING= ( wall)
MARKER_MONITORING= ( wall )

% ------------- COMMON PARAMETERS DEFINING THE NUMERICAL METHOD ---------------%
%
NUM_METHOD_GRAD= WEIGHTED_LEAST_SQUARES
CFL_NUMBER= 2.0
CFL_ADAPT= NO
CFL_ADAPT_PARAM= ( 0.5, 1.1, 1e-4, 2000.0)
ITER= 500000

% ------------------------ LINEAR SOLVER DEFINITION ---------------------------%
%
LINEAR_SOLVER= FGMRES
LINEAR_SOLVER_PREC= LU_SGS
LINEAR_SOLVER_ERROR= 1E-10
LINEAR_SOLVER_ITER= 20

% -------------------------- MULTIGRID PARAMETERS -----------------------------%
%
MGLEVEL= 3
MGCYCLE= V_CYCLE
MG_PRE_SMOOTH= ( 1, 1, 1, 1 )
MG_POST_SMOOTH= ( 0, 0, 0, 0 )
MG_CORRECTION_SMOOTH= ( 0, 0, 0, 0 )
MG_DAMP_RESTRICTION= 0.5
MG_DAMP_PROLONGATION= 0.5

% -------------------- FLOW NUMERICAL METHOD DEFINITION -----------------------%
%
CONV_NUM_METHOD_FLOW= HLLC
MUSCL_FLOW= YES
SLOPE_LIMITER_FLOW= VENKATAKRISHNAN
TIME_DISCRE_FLOW= EULER_IMPLICIT

% --------------------------- CONVERGENCE PARAMETERS --------------------------%
%
CONV_RESIDUAL_MINVAL= -15
CONV_STARTITER= 10
CONV_CAUCHY_ELEMS= 100
CONV_CAUCHY_EPS= 1E-7

% ------------------------- INPUT/OUTPUT INFORMATION --------------------------%
%
VOLUME_OUTPUT=DENSITY,ENERGY,PRESSURE,MACH,VELOCIT Y-X,VELOCITY-Y,VELOCITY-Z
MESH_FILENAME= cylinder_0.su2
MESH_FORMAT= SU2
MESH_OUT_FILENAME= mesh_out.su2
SOLUTION_FILENAME= restart_flow.csv
SOLUTION_ADJ_FILENAME= solution_adj.dat
TABULAR_FORMAT= CSV
CONV_FILENAME= history
RESTART_FILENAME= restart_flow.dat
RESTART_ADJ_FILENAME= restart_adj.dat
VOLUME_FILENAME= flow
VOLUME_ADJ_FILENAME= adjoint
GRAD_OBJFUNC_FILENAME= of_grad.dat
SURFACE_FILENAME= surface_flow
SURFACE_ADJ_FILENAME= surface_adjoint
SCREEN_OUTPUT= (INNER_ITER, RMS_DENSITY, RMS_ENERGY, CFL_NUMBER)
OUTPUT_FILES= ( RESTART_ASCII, PARAVIEW, SURFACE_PARAVIEW)
OUTPUT_WRT_FREQ=(100,100,100)

[2770363742@qq.com]

Have you resolved this problem? I've recently encountered the same problem.

[cucs77]

Hi, I perfomed several cases. In the case of viscous flow I advise you to use REF_DIMENSIONALIZATION = FREESTREAM_VEL_EQ_ONE. Furthermore, the slope limiter depends on the size of your boundary layer mesh. But I don't know what criteria must be followed..