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Old   December 24, 2024, 04:19
Default RAmjet inlet
  #1
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Süleyman
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Hello, I am working on ramjet inlet cfd but it says "SU2 has diverged (NaN detected)." Could you help me to use proper methods and options to solve my problem, what should I change in my settings. Analysis will run at 3 mach I am trying to find optimum back pressure for externally compressed ramjet inlet. Also what should be the boundary layer settings?




% ------------- DIRECT, ADJOINT, AND LINEARIZED PROBLEM DEFINITION ------------%
%
% Physical governing equations (EULER, NAVIER_STOKES,
% WAVE_EQUATION, HEAT_EQUATION, FEM_ELASTICITY,
% POISSON_EQUATION)
SOLVER= RANS

%
FLUID_MODEL= STANDARD_AIR
% Specify turbulence model (NONE, SA, SA_NEG, SST, SA_E, SA_COMP, SA_E_COMP, SST_SUST)

% Mathematical problem (DIRECT, CONTINUOUS_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

% ----------- COMPRESSIBLE AND INCOMPRESSIBLE FREE-STREAM DEFINITION ----------%
%
% Mach number (non-dimensional, based on the free-stream values)
MACH_NUMBER= 3
%
% Reynolds number (non-dimensional, based on the free-stream values)
REYNOLDS_NUMBER= 46.268E6
% Reynolds length (1 m, 1 inch by default)
REYNOLDS_LENGTH= 1
%
% Angle of attack (degrees)
AOA= 0.0
%
% Side-slip angle (degrees)
SIDESLIP_ANGLE= 0.0
%
% Free-stream pressure (101325.0 N/m^2 by default, only Euler flows)
FREESTREAM_PRESSURE= 101325
%
% Free-stream temperature (288.15 K by default)
FREESTREAM_TEMPERATURE= 300.0

INIT_OPTION= REYNOLDS
FREESTREAM_TURBULENCEINTENSITY= 0.01
FREESTREAM_OPTION= TEMPERATURE_FS

% ---------------------- REFERENCE VALUE DEFINITION ---------------------------%
%
% Reference origin for moment computation
REF_ORIGIN_MOMENT_X = 0.00
REF_ORIGIN_MOMENT_Y = 0.00
REF_ORIGIN_MOMENT_Z = 0.00
%
% Reference length for pitching, rolling, and yawing non-dimensional moment
REF_LENGTH= 1
%
% Reference area for force coefficients (0 implies automatic calculation)
REF_AREA= 0

% -------------------- 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_HEATFLUX= ( wall,0,axis,0)

MARKER_FAR= ( far_field )
%
% Supersonic inlet boundary marker(s) (NONE = no marker)
% Total Conditions: (inlet marker, temperature, static pressure, velocity_x,
% velocity_y, velocity_z, ... ), i.e. all variables specified.
MARKER_SUPERSONIC_INLET= ( inlet, 300.0, 101325, 1029, 0.0, 0.0 )
%
% Outlet boundary marker(s) (NONE = no marker)
% Format: ( outlet marker, back pressure (static), ... )
MARKER_OUTLET= ( outlet,500000)
%MARKER_PRESSURE= ( outlet, 2400000 )


%
% Marker(s) of the surface to be plotted or designed
MARKER_PLOTTING= ( wall )
%
% Marker(s) of the surface where the functional (Cd, Cl, etc.) will be evaluated
MARKER_MONITORING= ( wall )

MARKER_SUPERSONIC_OUTLET= ( far_field )


% Symmetry boundary marker(s) (NONE = no marker)
MARKER_SYM=(axis)

%MARKER_EULER=(axis)

%

% --------------------------- VISCOSITY MODEL ---------------------------------%
%
% Viscosity model (SUTHERLAND, CONSTANT_VISCOSITY).
VISCOSITY_MODEL= SUTHERLAND
%
% Sutherland Viscosity Ref (1.716E-5 default value for AIR SI)
MU_REF= 1.716E-5
%
% Sutherland Temperature Ref (273.15 K default value for AIR SI)
MU_T_REF= 273.15
%
% Sutherland constant (110.4 default value for AIR SI)
SUTHERLAND_CONSTANT= 110.4
%

% ------------- COMMON PARAMETERS DEFINING THE NUMERICAL METHOD ---------------%
%

%NUM_METHOD_GRAD_RECON= LEAST_SQUARES


%
% Courant-Friedrichs-Lewy condition of the finest grid
CFL_NUMBER= 2
%
% 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, 5.0, 1e10)
%
% Runge-Kutta alpha coefficients
RK_ALPHA_COEFF= ( 0.66667, 0.66667, 1.000000 )
%
% Number of total iterations
ITER= 5000
%
% Linear solver for the implicit formulation (BCGSTAB, FGMRES)
LINEAR_SOLVER= FGMRES
%
% Preconditioner of the Krylov linear solver (ILU, JACOBI, LINELET, LU_SGS)
LINEAR_SOLVER_PREC= ILU
%
% 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= 20

% -------------------------- MULTIGRID PARAMETERS -----------------------------%
%
% Multi-Grid Levels (0 = no multi-grid)
MGLEVEL= 0
%
% Multi-grid cycle (V_CYCLE, W_CYCLE, FULLMG_CYCLE)
MGCYCLE= W_CYCLE
%
% Multi-grid pre-smoothing level
MG_PRE_SMOOTH= ( 1, 2, 3, 3 )
%
% 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= 1
%
% Damping factor for the correction prolongation
MG_DAMP_PROLONGATION= 1
% -------------------- FLOW NUMERICAL METHOD 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=VENKATAKRISHNAN
%
% Coefficient for the limiter (smooth regions)
VENKAT_LIMITER_COEFF= 0.006
%
% 2nd and 4th order artificial dissipation coefficients
JST_SENSOR_COEFF= ( 0.5, 0.02 )
%
% Time discretization (RUNGE-KUTTA_EXPLICIT, EULER_IMPLICIT, EULER_EXPLICIT)
TIME_DISCRE_FLOW= EULER_IMPLICIT
% --------------------------- CONVERGENCE PARAMETERS --------------------------%
%
% Convergence criteria (CAUCHY, RESIDUAL)
CONV_FIELD= RMS_DENSITY
%
% Min value of the residual (log10 of the residual)
CONV_RESIDUAL_MINVAL= -8
%
% 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-10
% -------------------- 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

% ------------------------- INPUT/OUTPUT INFORMATION --------------------------%
%
% Mesh input file
%MESH_FILENAME= backp.su2
MESH_FILENAME= mach3_con.su2
%
% Mesh input file format (SU2, CGNS, NETCDF_ASCII)
MESH_FORMAT= SU2
%
% Mesh output file
MESH_OUT_FILENAME= mesh_out.su2
%
% Restart flow input file
SOLUTION_FILENAME= solution_flow.dat
%
% Restart adjoint input file
SOLUTION_ADJ_FILENAME= solution_adj.dat
%
% Output tabular format (CSV, TECPLOT)
TABULAR_FORMAT= CSV
%
% Output file convergence history (w/o extension)
CONV_FILENAME= history
%
% Output file restart flow
RESTART_FILENAME= restart_flow.dat
%
% Output file restart adjoint
RESTART_ADJ_FILENAME= restart_adj.dat
%
% Output file flow (w/o extension) variables
VOLUME_FILENAME= flow_con_3M_500KPa
%
% 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_FILENAME= surface_flow
%
% Output file surface adjoint coefficient (w/o extension)
SURFACE_ADJ_FILENAME= surface_adjoint
%
%
% Screen output
SCREEN_OUTPUT=(INNER_ITER, WALL_TIME, RMS_DENSITY, RMS_ENERGY, LIFT, DRAG)


% Writing frequency for screen output
SCREEN_WRT_FREQ_INNER= 100
%
SCREEN_WRT_FREQ_OUTER= 100
%
SCREEN_WRT_FREQ_TIME= 100
%
% Writing frequency for history output
HISTORY_WRT_FREQ_INNER= 10
%
HISTORY_WRT_FREQ_OUTER= 10
%
HISTORY_WRT_FREQ_TIME= 10

% ----------------------- DESIGN VARIABLE PARAMETERS --------------------------%
%
%
% Kind of deformation (NO_DEfFORMATION, SCALE_GRID, TRANSLATE_GRID, ROTATE_GRID,
% FFD_SETTING, FFD_NACELLE,
% FFD_CONTROL_POINT, FFD_CAMBER, FFD_THICKNESS, FFD_TWIST
% FFD_CONTROL_POINT_2D, FFD_CAMBER_2D, FFD_THICKNESS_2D,
% FFD_TWIST_2D, HICKS_HENNE, SURFACE_BUMP, SURFACE_FILE)
DV_KIND= SCALE_GRID
%
% - NO_DEFORMATION ( 1.0 )
% - TRANSLATE_GRID ( x_Disp, y_Disp, z_Disp ), as a unit vector
% - ROTATE_GRID ( x_Orig, y_Orig, z_Orig, x_End, y_End, z_End ) axis, DV_VALUE in deg.
% - SCALE_GRID ( 1.0 )
DV_PARAM= ( 1.0 )
%
% Value of the deformation
DV_VALUE= 10.0


%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%5
AXISYMMETRIC= YES
% Convective numerical method (JST, LAX-FRIEDRICH, CUSP, ROE, AUSM, HLLC,
% TURKEL_PREC, MSW)
CONV_NUM_METHOD_FLOW= AUSM
% Specify turbulence model (NONE, SA, SA_NEG, SST, SA_E, SA_COMP, SA_E_COMP, SST_SUST)
KIND_TURB_MODEL=SST
%SST_OPTIONS=V2003m
%SA_OPTIONS=EDWARDS
% Numerical method for spatial gradients (GREEN_GAUSS, LEAST_SQUARES,
% WEIGHTED_LEAST_SQUARES)
NUM_METHOD_GRAD=WEIGHTED_LEAST_SQUARES




and this is the .geo file:


// Gmsh project created on Thu Dec 19 00:17:59 2024
SetFactory("OpenCASCADE");
//+
Point(1) = {0, 0, 0, 1.0};
//+
Point(2) = {0.5, 0, 0, 1.0};
//+
Point(3) = {0.75, 0.053, 0, 1.0};
//+
Point(4) = {1, 0.1129, 0, 1.0};
//+
Point(5) = {1.25, 0.189, 0, 1.0};
//+
Point(6) = {1.4, 0.255, 0, 1.0};
//+
Point(7) = {1.5, 0.26, 0, 1.0};
//+
Point(8) = {1.6, 0.26, 0, 1.0};
//+
Point(9) = {2, 0.26, 0, 1.0};
//+
Point(10) = {3, 0.15 ,0, 1.0};
//+
Point(11) = {3, 0.4247, 0, 1.0};
//+
Point(12) = {1.4, 0.4247, 0, 1.0};
//+
Point(13) = {2, 0.5, 0, 1.0};
//+
Point(14) = {3, 0.5, 0, 1.0};
//+
Point(15) = {3, 1, 0, 1.0};
//+
Point(16) = {0, 1, 0, 1.0};
//+
Line(1) = {1, 2};
//+
Line(2) = {2, 3};
//+
Line(3) = {3, 4};
//+
Line(4) = {4, 5};
//+
Line(5) = {5, 6};
//+
Line(6) = {6, 7};
//+
Line(7) = {7, 8};
//+
Line(8) = {8, 9};
//+
Line(9) = {9, 10};
//+
Line(10) = {10, 11};
//+
Line(11) = {11, 12};
//+
Line(12) = {12, 13};
//+
Line(13) = {13, 14};
//+
Line(14) = {14, 15};
//+
Line(15) = {15, 16};
//+
Line(16) = {16, 1};

//+
Physical Curve("inlet") = {16};
//+
Physical Curve("far_field") = {15, 14};
//+
Physical Curve("outlet") = {10};
//+
Physical Curve("axis") = {1};
//+
Physical Curve("wall") = {13, 12, 11, 9, 8, 7, 6, 5, 4, 3, 2};
//+
Transfinite Curve { 11} = 201 Using Progression 1;
//+
Transfinite Curve {9, 13,16} = 101 Using Progression 1;
//+
Transfinite Curve {1, 8,14} = 51 Using Progression 1;
//+

Transfinite Curve {2, 3, 4, 5} = 31 Using Progression 1;

Transfinite Curve {6,7} = 21 Using Progression 1;
//+
Transfinite Curve {12} = 71 Using Progression 1;
//+
Transfinite Curve {13} = 81 Using Progression 1;
//+

//+
Transfinite Curve {15} = 251 Using Progression 1;
//+
Transfinite Curve {10} = 61 Using Progression 1;

//+

//+
Curve Loop(1) = {16, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15};
//+
Plane Surface(1) = {1};





Field[1] = BoundaryLayer;
Field[1].EdgesList = {12, 11, 9, 8, 7, 6, 5, 4, 3, 2,13,1,10}; // The "wall" line ID
Field[1].hfar = 0.005;
Field[1].hwall_n = 0.0005;
Field[1].thickness = 0.005;
Field[1].ratio = 1.2;
Field[1].IntersectMetrics = 0;
Field[1].Quads = 1;
BoundaryLayer Field = 1;
sulo33 is offline   Reply With Quote

Old   December 24, 2024, 14:32
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bigfoot
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Do you really have a 3 meter long ramjet?
Because that size might give you some difficulty. If you have viscous flow you need to properly resolve the boundary layer, and this requires a lot of cells. It probably diverges because your mesh is not fine enough to properly resolve this.



I think this is a mistake, maybe you can check what the actual dimensions of your setup are, it is probably smaller than what you have right now. I also see that you have defined transfinite lines but no transfinite surfaces. A transfinite surface will get you a very well defined, structured mesh of a higher quality than the unstructured triangulation that you have right now.



There is also a mistake in your setup, and in SU2 because it did not complain about it:
you define your boundary "far_field" as a far-field as well as a supersonic outlet. It should be one or the other., probably far-field is fine. Your marker_outlet(outlet) should probably be marker_supersonic_outlet(outlet)
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