[AlexJoh]

Hi everyone !

I am a new user of SU2 and I wish to simulate a Hartmann-Sprenger tube. First, to get some practice, I try to simulate the shock diamonds with some pressurized air entering my nozzle.

The problem I have is that I get a code divergence for an inlet pressure higher than 9 bars (outlet pressure is 1 bar). I tried restarting from a lower pressure solution but it didn't work. I have attached a solution at 7 bars.
Does anyone have an idea ?


Here is my input file :

% ------------- DIRECT, ADJOINT, AND LINEARIZED PROBLEM DEFINITION ------------%
%
% Physical governing equations (EULER, NAVIER_STOKES,
%                               FEM_EULER, FEM_NAVIER_STOKES, FEM_RANS, FEM_LES,
%                               WAVE_EQUATION, HEAT_EQUATION, FEM_ELASTICITY,
%                               POISSON_EQUATION)
SOLVER= EULER
%
% Mathematical problem (DIRECT, CONTINUOUS_ADJOINT, DISCRETE_ADJOINT)
MATH_PROBLEM= DIRECT
%
% Restart solution (NO, YES)
RESTART_SOL= NO
%
% System of measurements (SI, US)
% International system of units (SI): ( meters, kilograms, Kelvins,
%                                       Newtons = kg m/s^2, Pascals = N/m^2,
%                                       Density = kg/m^3, Speed = m/s,
%                                       Equiv. Area = m^2 )
% United States customary units (US): ( inches, slug, Rankines, lbf = slug ft/s^2,
%                                       psf = lbf/ft^2, Density = slug/ft^3,
%                                       Speed = ft/s, Equiv. Area = ft^2 )
SYSTEM_MEASUREMENTS= SI
%
AXISYMMETRIC=YES

% -------------------- COMPRESSIBLE FREE-STREAM DEFINITION --------------------%
%
% Mach number (non-dimensional, based on the free-stream values)
MACH_NUMBER= 1E-9
%
% Angle of attack (degrees, only for compressible flows)
AOA= 0.0
%
% 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= 100000
%
% Free-stream temperature (288.15 K, 518.67 R by default)
FREESTREAM_TEMPERATURE= 288.15
%
% Compressible flow non-dimensionalization (DIMENSIONAL, FREESTREAM_PRESS_EQ_ONE,
%                              FREESTREAM_VEL_EQ_MACH, FREESTREAM_VEL_EQ_ONE)
REF_DIMENSIONALIZATION= DIMENSIONAL

% ---- 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)
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
%
% Critical Temperature (131.00 K by default)
CRITICAL_TEMPERATURE= 131.00
%
% Critical Pressure (3588550.0 N/m^2 by default)
CRITICAL_PRESSURE= 3588550.0
%
% Acentric factor (0.035 (air))
ACENTRIC_FACTOR= 0.035

% --------------------------- VISCOSITY MODEL ---------------------------------%
%
% Viscosity model (SUTHERLAND, CONSTANT_VISCOSITY, POLYNOMIAL_VISCOSITY).
VISCOSITY_MODEL= CONSTANT_VISCOSITY
%
% Molecular Viscosity that would be constant (1.716E-5 by default)
MU_CONSTANT= 1.716E-5

% --------------------------- THERMAL CONDUCTIVITY MODEL ----------------------%
%
% Laminar Conductivity model (CONSTANT_CONDUCTIVITY, CONSTANT_PRANDTL,
% POLYNOMIAL_CONDUCTIVITY).
CONDUCTIVITY_MODEL= CONSTANT_PRANDTL
%
% -------------------- BOUNDARY CONDITION DEFINITION --------------------------%
%
% Navier-Stokes (no-slip), constant heat flux wall  marker(s) (NONE = no marker)
% Format: ( marker name, constant heat flux (J/m^2), ... )
MARKER_EULER= ( Wall)
%
% Symmetry boundary marker(s) (NONE = no marker)
MARKER_SYM= ( Symmetry )
%
INLET_TYPE=TOTAL_CONDITIONS
MARKER_INLET=( Inlet, 288.15, 400000, 1.0, 0.0, 0.0)
%
INC_OUTLET_TYPE=PRESSURE_OUTLET
MARKER_OUTLET=(Outlet, 100000)

% ------------- COMMON PARAMETERS DEFINING THE NUMERICAL METHOD ---------------%
%
% Numerical method for spatial gradients (GREEN_GAUSS, WEIGHTED_LEAST_SQUARES)
NUM_METHOD_GRAD= GREEN_GAUSS
%
% CFL number (initial value for the adaptive CFL number)
CFL_NUMBER= 10.0
%
% Adaptive CFL number (NO, YES)
CFL_ADAPT= YES
%
% Parameters of the adaptive CFL number (factor down, factor up, CFL min value,
%                                        CFL max value )
CFL_ADAPT_PARAM= ( 0.1, 2.0, 10.0, 1000.0 )
%
% Maximum Delta Time in local time stepping simulations
MAX_DELTA_TIME= 1E6

% ----------- SLOPE LIMITER AND DISSIPATION SENSOR DEFINITION -----------------%
%
% Monotonic Upwind Scheme for Conservation Laws (TVD) in the flow equations.
%           Required for 2nd order upwind schemes (NO, YES)
MUSCL_FLOW= NO
%
% Slope limiter (NONE, VENKATAKRISHNAN, VENKATAKRISHNAN_WANG,
%                BARTH_JESPERSEN, VAN_ALBADA_EDGE)
SLOPE_LIMITER_FLOW= NONE
%
% Monotonic Upwind Scheme for Conservation Laws (TVD) in the turbulence equations.
%           Required for 2nd order upwind schemes (NO, YES)
MUSCL_TURB= NO

% ------------------------ LINEAR SOLVER DEFINITION ---------------------------%
%
% Linear solver or smoother for implicit formulations (BCGSTAB, FGMRES, SMOOTHER_JACOBI,
%                                                      SMOOTHER_ILU, SMOOTHER_LUSGS,
%                                                      SMOOTHER_LINELET)
LINEAR_SOLVER= FGMRES
%
% Preconditioner of the Krylov linear solver (ILU, LU_SGS, LINELET, JACOBI)
LINEAR_SOLVER_PREC= ILU
%
% 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-6
%
% Max number of iterations of the linear solver for the implicit formulation
LINEAR_SOLVER_ITER= 10

% -------------------------- MULTIGRID PARAMETERS -----------------------------%
%
% Multi-grid levels (0 = no multi-grid)
MGLEVEL= 0

% -------------------- FLOW NUMERICAL METHOD DEFINITION -----------------------%
%
% Convective numerical method (JST, LAX-FRIEDRICH, CUSP, ROE, AUSM, AUSMPLUSUP, AUSMPLUSUP2, HLLC,
%                              TURKEL_PREC, MSW, FDS)
CONV_NUM_METHOD_FLOW= ROE
%
% Entropy fix coefficient (0.0 implies no entropy fixing, 1.0 implies scalar
%                          artificial dissipation)
ENTROPY_FIX_COEFF= 0.1
%
% 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
%
% Time discretization (EULER_IMPLICIT)
TIME_DISCRE_TURB= EULER_IMPLICIT
%
% Reduction factor of the CFL coefficient in the turbulence problem
CFL_REDUCTION_TURB= 1.0

% --------------------------- CONVERGENCE PARAMETERS --------------------------%
%
% Number of total iterations
ITER= 1000
%
% Convergence criteria (CAUCHY, RESIDUAL)
%
CONV_CRITERIA= RESIDUAL
%
%
% Min value of the residual (log10 of the residual)
CONV_RESIDUAL_MINVAL= -24
%
% Start convergence criteria at iteration number
CONV_STARTITER= 10

% ------------------------- INPUT/OUTPUT INFORMATION --------------------------%
%
% Mesh input file
MESH_FILENAME= mesh_buse_raffine.su2
%
% Mesh input file format (SU2, CGNS)
MESH_FORMAT= SU2
%
% Mesh output file
MESH_OUT_FILENAME= mesh_out.su2
%
% Restart flow input file
SOLUTION_FILENAME= solution_flow.dat
%
% Output file format (TECPLOT, TECPLOT_BINARY, PARAVIEW, PARAVIEW_BINARY,
%                     FIELDVIEW, FIELDVIEW_BINARY)
TABULAR_FORMAT= CSV
%
% Output file convergence history (w/o extension)
CONV_FILENAME= history
%
% 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
%
% Writing solution file frequency
WRT_SOL_FREQ=1000
%
% Screen output
SCREEN_OUTPUT= (TIME_ITER, INNER_ITER, RMS_DENSITY)

[pcg]

At those pressures maybe you can use supersonic inlet/outlet? ( MARKER_SUPERSONIC_...)
You can also try to disable the CFL adaption or reducing the maximum value (the 1000 you have now) as that may cause the linear solver to blow up in a single iteration.

[AlexJoh]

Thanks for your help.

I reduced the CFL max value to 50 and it worked well but only with the Navier-Stokes solver (I reached an inlet pressure of 30 bars by using restart solutions).
In fact, I have a "non physical point" when I get to an inlet pressure of more than 9 bars using the Euler solver. Do you have any idea ?

I am now working on the whole Hartmann-Sprenger tube adding a time domain.

[pcg]

If you have a viscous wall intersecting an inlet that non physical point will probably never disappear.