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Old   January 30, 2021, 04:55
Default Solver parameters to solve convergence issue
  #1
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William Haigh
Join Date: Aug 2020
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Hi everyone,
I am attempting to run an unsteady flow simulation around a scramjet inlet geometry. I have successfully solved for it using subsonic freestream conditions. I am inputting a pitching moment to see how the flow reacts to a change in pitch.
However, I want to change the freestream conditions to supersonic:
M = 5.1
P = 4488 Pa
T = 217.92K
I have inputted these parameters and changed the solver parameters from JST to SLAU2 but it is not converging. I will paste my configuration file here.

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% %
% SU2 configuration file %
% Case description: Pitching scramjet inlet simulating gust %
% Author: William Haigh %
% Institution: University of Bristol %
% Date: 2021.01.30 %
% File Version 7.1.0 "Blackbird" %
% %
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

% ------------- DIRECT, ADJOINT, AND LINEARIZED PROBLEM DEFINITION ------------%
%
% Physical governing equations (EULER, NAVIER_STOKES,
% WAVE_EQUATION, HEAT_EQUATION, FEM_ELASTICITY,
% POISSON_EQUATION)
SOLVER= EULER
%
% Specify turbulent model (NONE, SA, SA_NEG, SST)
KIND_TURB_MODEL= NONE
%
% Mathematical problem (DIRECT, CONTINUOUS_ADJOINT)
MATH_PROBLEM= DIRECT
%
% Restart solution (NO, YES)
RESTART_SOL= NO

% ------------------------- UNSTEADY SIMULATION -------------------------------%
%
% Unsteady simulation (NO, TIME_STEPPING, DUAL_TIME_STEPPING-1ST_ORDER,
% DUAL_TIME_STEPPING-2ND_ORDER)
TIME_MARCHING= DUAL_TIME_STEPPING-2ND_ORDER
%
TIME_DOMAIN = YES
%
% Time Step for dual time stepping simulations (s)
TIME_STEP= 0.0023555025613149587
% 24 steps per period: 0.0024536485013697488
% 25 steps per period: 0.0023555025613149587
%
% Total Physical Time for dual time stepping simulations (s)
MAX_TIME= 0.59
% 10 periods: 0.5888756403287397
%
% Number of internal iterations (dual time method)
INNER_ITER= 400
%
% Starting direct iteration for unsteady adjoint
UNST_ADJOINT_ITER= 251
%
% Number of total iterations
TIME_ITER= 255

% ----------------------- DYNAMIC MESH DEFINITION -----------------------------%
% Type of mesh motion (NONE, FLUTTER, RIGID_MOTION)
%GRID_MOVEMENT= RIGID_MOTION
%
SURFACE_MOVEMENT= DEFORMING

MARKER_MOVING= airfoil
% Motion mach number (non-dimensional). Used for initializing a viscous flow
% with the Reynolds number and for computing force coeffs. with dynamic meshes.
MACH_MOTION= 5.1
%
% Coordinates of the rigid motion origin
SURFACE_MOTION_ORIGIN= 0.248 0.0 0.0
%
% Pitching angular freq. (rad/s) about x, y, & z axes (RIGID_MOTION only)
SURFACE_PITCHING_OMEGA= 0.0 0.0 106.69842
%
% Pitching amplitude (degrees) about x, y, & z axes (RIGID_MOTION only)
SURFACE_PITCHING_AMPL= 0.0 0.0 10.01
% ----------- COMPRESSIBLE AND INCOMPRESSIBLE FREE-STREAM DEFINITION ----------%
%
% Mach number (non-dimensional, based on the free-stream values)
MACH_NUMBER= 5.1
%
% Angle of attack (degrees)
AOA= 0.0
%
% Free-stream pressure (101325.0 N/m^2 by default, only Euler flows)
FREESTREAM_PRESSURE= 4488
%
% Free-stream temperature (288.15 K by default)
FREESTREAM_TEMPERATURE= 217.92

% ---------------------- REFERENCE VALUE DEFINITION ---------------------------%
%
% Reference origin for moment computation
REF_ORIGIN_MOMENT_X = 0.248
REF_ORIGIN_MOMENT_Y = 0.00
REF_ORIGIN_MOMENT_Z = 0.00
%
% Reference length for pitching, rolling, and yawing non-dimensional moment
REF_LENGTH= 1.0
%
% Reference area for force coefficients (0 implies automatic calculation)
REF_AREA= 1.0

% ----------------------- BOUNDARY CONDITION DEFINITION -----------------------%
%
% Marker of the Euler boundary (0 = no marker)
MARKER_EULER= ( airfoil )
%
% Marker of the far field (0 = no marker)
MARKER_FAR= ( farfield )

% ------------------------ SURFACES IDENTIFICATION ----------------------------%
%
% Marker(s) of the surface in the surface flow solution file
MARKER_PLOTTING = ( airfoil )
%
% Marker(s) of the surface where the non-dimensional coefficients are evaluated.
MARKER_MONITORING = ( airfoil )
%
% 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= 100.0
%
% 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, 1.0, 1e10 )
%
% Runge-Kutta alpha coefficients
RK_ALPHA_COEFF= ( 0.66667, 0.66667, 1.000000 )
%

% ------------------------ 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= 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= 10

% -------------------------- 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 PreSmoothing Level
MG_PRE_SMOOTH= ( 1, 2, 3, 3 )
%
% Multi-Grid PostSmoothing 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= 0.9
%
% Damping factor for the correction prolongation
MG_DAMP_PROLONGATION= 0.9

% -------------------- FLOW NUMERICAL METHOD DEFINITION -----------------------%
%
% Convective numerical method (JST, LAX-FRIEDRICH, CUSP, ROE, AUSM, HLLC,
% TURKEL_PREC, MSW)
CONV_NUM_METHOD_FLOW= SLAU2
%
% Allows much higher CFL
USE_ACCURATE_FLUX_JACOBIANS=YES
%
% Monotonic Upwind Scheme for Conservation Laws (TVD) in the flow equations.
% Required for 2nd order upwind schemes (NO, YES)
MUSCL_FLOW= YES
%
% Slope limiter (VENKATAKRISHNAN, MINMOD)
SLOPE_LIMITER_FLOW= VENKATAKRISHNAN_WANG
%
% Coefficient for the limiter (smooth regions)
VENKAT_LIMITER_COEFF= 0.05
%
% 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

% ---------------- 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)
OBJECTIVE_FUNCTION= DRAG
%
% Convective numerical method (JST, LAX-FRIEDRICH, ROE)
CONV_NUM_METHOD_ADJFLOW= SLAU2
%
% Monotonic Upwind Scheme for Conservation Laws (TVD) in the adjoint flow equations.
% Required for 2nd order upwind schemes (NO, YES)
MUSCL_ADJFLOW= YES
%
% Slope limiter (NONE, VENKATAKRISHNAN, BARTH_JESPERSEN, VAN_ALBADA_EDGE,
% SHARP_EDGES, WALL_DISTANCE)
SLOPE_LIMITER_ADJFLOW= VENKATAKRISHNAN_WANG
%
% 2nd, and 4th order artificial dissipation coefficients
ADJ_JST_SENSOR_COEFF= ( 0.5, 0.02 )
%
% Reduction factor of the CFL coefficient in the adjoint problem
CFL_REDUCTION_ADJFLOW= 0.8
%
% Time discretization (RUNGE-KUTTA_EXPLICIT, EULER_IMPLICIT)
TIME_DISCRE_ADJFLOW= EULER_IMPLICIT
%
% Adjoint frozen viscosity (NO, YES)
FROZEN_VISC_CONT= YES

% ----------------------- GEOMETRY EVALUATION PARAMETERS ----------------------%
%
% Marker(s) of the surface where geometrical based function will be evaluated
GEO_MARKER= ( airfoil )
%
% Description of the geometry to be analyzed (AIRFOIL, WING, FUSELAGE)
GEO_DESCRIPTION= AIRFOIL
%
% Geometrical evaluation mode (FUNCTION, GRADIENT)
GEO_MODE= FUNCTION

% ------------------------ GRID DEFORMATION PARAMETERS ------------------------%
% Kind of deformation (FFD_SETTING, 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= 0.0

% --------------------------- CONVERGENCE PARAMETERS --------------------------%
% Convergence criteria (CAUCHY, RESIDUAL)
%
CONV_CRITERIA= RESIDUAL
%
%
% Min value of the residual (log10 of the residual)
CONV_RESIDUAL_MINVAL= -10
%
% Start Cauchy 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
%

% ------------------------- INPUT/OUTPUT INFORMATION --------------------------%
%
% Mesh input file
MESH_FILENAME= 2Dmeshgap.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= restart_flow.dat
%
% Output file format (PARAVIEW, TECPLOT, STL)
OUTPUT_FILES = PARAVIEW_ASCII
%
% 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= pitchscramsupersonic
%
% 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
%
% Writing solution file frequency
OUTPUT_WRT_FREQ= 250
%

% --------------------- OPTIMAL SHAPE DESIGN DEFINITION -----------------------%
%
% Available flow based objective functions or constraint functions
% DRAG, LIFT, SIDEFORCE, EFFICIENCY, BUFFET,
% FORCE_X, FORCE_Y, FORCE_Z,
% MOMENT_X, MOMENT_Y, MOMENT_Z,
% THRUST, TORQUE, FIGURE_OF_MERIT,
% EQUIVALENT_AREA, NEARFIELD_PRESSURE,
% TOTAL_HEATFLUX, MAXIMUM_HEATFLUX,
% INVERSE_DESIGN_PRESSURE, INVERSE_DESIGN_HEATFLUX,
% SURFACE_TOTAL_PRESSURE, SURFACE_MASSFLOW
% SURFACE_STATIC_PRESSURE, SURFACE_MACH
%
% Available geometrical based objective functions or constraint functions
% AIRFOIL_AREA, AIRFOIL_THICKNESS, AIRFOIL_CHORD, AIRFOIL_TOC, AIRFOIL_AOA,
% WING_VOLUME, WING_MIN_THICKNESS, WING_MAX_THICKNESS, WING_MAX_CHORD, WING_MIN_TOC, WING_MAX_TWIST, WING_MAX_CURVATURE, WING_MAX_DIHEDRAL
% STATION#_WIDTH, STATION#_AREA, STATION#_THICKNESS, STATION#_CHORD, STATION#_TOC,
% STATION#_TWIST (where # is the index of the station defined in GEO_LOCATION_STATIONS)
%
% Available design variables
% 2D Design variables
% FFD_CONTROL_POINT_2D ( 19, Scale | Mark. List | FFD_BoxTag, i_Ind, j_Ind, x_Mov, y_Mov )
% FFD_CAMBER_2D ( 20, Scale | Mark. List | FFD_BoxTag, i_Ind )
% FFD_THICKNESS_2D ( 21, Scale | Mark. List | FFD_BoxTag, i_Ind )
% FFD_TWIST_2D ( 22, Scale | Mark. List | FFD_BoxTag, x_Orig, y_Orig )
% HICKS_HENNE ( 30, Scale | Mark. List | Lower(0)/Upper(1) side, x_Loc )
% ANGLE_OF_ATTACK ( 101, Scale | Mark. List | 1.0 )
%
% 3D Design variables
% FFD_CONTROL_POINT ( 11, Scale | Mark. List | FFD_BoxTag, i_Ind, j_Ind, k_Ind, x_Mov, y_Mov, z_Mov )
% FFD_NACELLE ( 12, Scale | Mark. List | FFD_BoxTag, rho_Ind, theta_Ind, phi_Ind, rho_Mov, phi_Mov )
% FFD_GULL ( 13, Scale | Mark. List | FFD_BoxTag, j_Ind )
% FFD_CAMBER ( 14, Scale | Mark. List | FFD_BoxTag, i_Ind, j_Ind )
% FFD_TWIST ( 15, Scale | Mark. List | FFD_BoxTag, j_Ind, x_Orig, y_Orig, z_Orig, x_End, y_End, z_End )
% FFD_THICKNESS ( 16, Scale | Mark. List | FFD_BoxTag, i_Ind, j_Ind )
% FFD_ROTATION ( 18, Scale | Mark. List | FFD_BoxTag, x_Axis, y_Axis, z_Axis, x_Turn, y_Turn, z_Turn )
% FFD_ANGLE_OF_ATTACK ( 24, Scale | Mark. List | FFD_BoxTag, 1.0 )
%
% Global design variables
% TRANSLATION ( 1, Scale | Mark. List | x_Disp, y_Disp, z_Disp )
% ROTATION ( 2, Scale | Mark. List | x_Axis, y_Axis, z_Axis, x_Turn, y_Turn, z_Turn )

% Optimization objective function with optional scaling factor
% ex= Objective * Scale
OPT_OBJECTIVE= DRAG * 0.001

% Optimization constraint functions with scaling factors, separated by semicolons
% ex= (Objective = Value ) * Scale, use '>','<','='
OPT_CONSTRAINT= ( LIFT = 0.0 ) * 0.001; ( AREA > 0.0660957 ) * 0.001
%
% List of design variables (Design variables are separated by semicolons)
DEFINITION_DV= ( 30, 1.0 | airfoil | 0, 0.961538461538 ); ( 30, 1.0 | airfoil | 0, 0.923076923077 ); ( 30, 1.0 | airfoil | 0, 0.884615384615 ); ( 30, 1.0 | airfoil | 0, 0.846153846154 ); ( 30, 1.0 | airfoil | 0, 0.807692307692 ); ( 30, 1.0 | airfoil | 0, 0.769230769231 ); ( 30, 1.0 | airfoil | 0, 0.730769230769 ); ( 30, 1.0 | airfoil | 0, 0.692307692308 ); ( 30, 1.0 | airfoil | 0, 0.653846153846 ); ( 30, 1.0 | airfoil | 0, 0.615384615385 ); ( 30, 1.0 | airfoil | 0, 0.576923076923 ); ( 30, 1.0 | airfoil | 0, 0.538461538462 ); ( 30, 1.0 | airfoil | 0, 0.5 ); ( 30, 1.0 | airfoil | 0, 0.461538461538 ); ( 30, 1.0 | airfoil | 0, 0.423076923077 ); ( 30, 1.0 | airfoil | 0, 0.384615384615 ); ( 30, 1.0 | airfoil | 0, 0.346153846154 ); ( 30, 1.0 | airfoil | 0, 0.307692307692 ); ( 30, 1.0 | airfoil | 0, 0.269230769231 ); ( 30, 1.0 | airfoil | 0, 0.230769230769 ); ( 30, 1.0 | airfoil | 0, 0.192307692308 ); ( 30, 1.0 | airfoil | 0, 0.153846153846 ); ( 30, 1.0 | airfoil | 0, 0.115384615385 ); ( 30, 1.0 | airfoil | 0, 0.0769230769231 ); ( 30, 1.0 | airfoil | 0, 0.0384615384615 ); ( 30, 1.0 | airfoil | 1, 0.0384615384615 ); ( 30, 1.0 | airfoil | 1, 0.0769230769231 ); ( 30, 1.0 | airfoil | 1, 0.115384615385 ); ( 30, 1.0 | airfoil | 1, 0.153846153846 ); ( 30, 1.0 | airfoil | 1, 0.192307692308 ); ( 30, 1.0 | airfoil | 1, 0.230769230769 ); ( 30, 1.0 | airfoil | 1, 0.269230769231 ); ( 30, 1.0 | airfoil | 1, 0.307692307692 ); ( 30, 1.0 | airfoil | 1, 0.346153846154 ); ( 30, 1.0 | airfoil | 1, 0.384615384615 ); ( 30, 1.0 | airfoil | 1, 0.423076923077 ); ( 30, 1.0 | airfoil | 1, 0.461538461538 ); ( 30, 1.0 | airfoil | 1, 0.5 ); ( 30, 1.0 | airfoil | 1, 0.538461538462 ); ( 30, 1.0 | airfoil | 1, 0.576923076923 ); ( 30, 1.0 | airfoil | 1, 0.615384615385 ); ( 30, 1.0 | airfoil | 1, 0.653846153846 ); ( 30, 1.0 | airfoil | 1, 0.692307692308 ); ( 30, 1.0 | airfoil | 1, 0.730769230769 ); ( 30, 1.0 | airfoil | 1, 0.769230769231 ); ( 30, 1.0 | airfoil | 1, 0.807692307692 ); ( 30, 1.0 | airfoil | 1, 0.846153846154 ); ( 30, 1.0 | airfoil | 1, 0.884615384615 ); ( 30, 1.0 | airfoil | 1, 0.923076923077 ); ( 30, 1.0 | airfoil | 1, 0.961538461538 )


If anyone has any advice on how to resolve this convergence issue, that would be great!!
Thanks,
William
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Old   February 1, 2021, 14:03
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Wally Maier
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Hi William,

I am very interested in the simulations you are running, though I have little experience with the dynamic mesh functionality.

SLAU2 should be a solid choice, but you can AUSM as well. My guess is there is something that the dynamic mesh solver and high speeds that dont interact well. There are a couple of people working with high speed flows that may have other advice!

Best,
Wally
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Old   February 2, 2021, 03:27
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William Haigh
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Hi Wally,
Thanks for your input! So you think I should play with the dynamic mesh parameters and see if I can resolve some issues?
I myself am also very new to this.
Any other advice would be great!
Thanks,
William
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Old   February 4, 2021, 14:06
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Pay D.
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Quote:
Originally Posted by WilliamH View Post
Hi everyone,
I am attempting to run an unsteady flow simulation around a scramjet inlet geometry. I have successfully solved for it using subsonic freestream conditions. I am inputting a pitching moment to see how the flow reacts to a change in pitch.
However, I want to change the freestream conditions to supersonic:
M = 5.1
P = 4488 Pa
T = 217.92K
I have inputted these parameters and changed the solver parameters from JST to SLAU2 but it is not converging. I will paste my configuration file here.

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% %
% SU2 configuration file %
% Case description: Pitching scramjet inlet simulating gust %
% Author: William Haigh %
% Institution: University of Bristol %
% Date: 2021.01.30 %
% File Version 7.1.0 "Blackbird" %
% %
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

% ------------- DIRECT, ADJOINT, AND LINEARIZED PROBLEM DEFINITION ------------%
%
% Physical governing equations (EULER, NAVIER_STOKES,
% WAVE_EQUATION, HEAT_EQUATION, FEM_ELASTICITY,
% POISSON_EQUATION)
SOLVER= EULER
%
% Specify turbulent model (NONE, SA, SA_NEG, SST)
KIND_TURB_MODEL= NONE
%
% Mathematical problem (DIRECT, CONTINUOUS_ADJOINT)
MATH_PROBLEM= DIRECT
%
% Restart solution (NO, YES)
RESTART_SOL= NO

% ------------------------- UNSTEADY SIMULATION -------------------------------%
%
% Unsteady simulation (NO, TIME_STEPPING, DUAL_TIME_STEPPING-1ST_ORDER,
% DUAL_TIME_STEPPING-2ND_ORDER)
TIME_MARCHING= DUAL_TIME_STEPPING-2ND_ORDER
%
TIME_DOMAIN = YES
%
% Time Step for dual time stepping simulations (s)
TIME_STEP= 0.0023555025613149587
% 24 steps per period: 0.0024536485013697488
% 25 steps per period: 0.0023555025613149587
%
% Total Physical Time for dual time stepping simulations (s)
MAX_TIME= 0.59
% 10 periods: 0.5888756403287397
%
% Number of internal iterations (dual time method)
INNER_ITER= 400
%
% Starting direct iteration for unsteady adjoint
UNST_ADJOINT_ITER= 251
%
% Number of total iterations
TIME_ITER= 255

% ----------------------- DYNAMIC MESH DEFINITION -----------------------------%
% Type of mesh motion (NONE, FLUTTER, RIGID_MOTION)
%GRID_MOVEMENT= RIGID_MOTION
%
SURFACE_MOVEMENT= DEFORMING

MARKER_MOVING= airfoil
% Motion mach number (non-dimensional). Used for initializing a viscous flow
% with the Reynolds number and for computing force coeffs. with dynamic meshes.
MACH_MOTION= 5.1
%
% Coordinates of the rigid motion origin
SURFACE_MOTION_ORIGIN= 0.248 0.0 0.0
%
% Pitching angular freq. (rad/s) about x, y, & z axes (RIGID_MOTION only)
SURFACE_PITCHING_OMEGA= 0.0 0.0 106.69842
%
% Pitching amplitude (degrees) about x, y, & z axes (RIGID_MOTION only)
SURFACE_PITCHING_AMPL= 0.0 0.0 10.01
% ----------- COMPRESSIBLE AND INCOMPRESSIBLE FREE-STREAM DEFINITION ----------%
%
% Mach number (non-dimensional, based on the free-stream values)
MACH_NUMBER= 5.1
%
% Angle of attack (degrees)
AOA= 0.0
%
% Free-stream pressure (101325.0 N/m^2 by default, only Euler flows)
FREESTREAM_PRESSURE= 4488
%
% Free-stream temperature (288.15 K by default)
FREESTREAM_TEMPERATURE= 217.92

% ---------------------- REFERENCE VALUE DEFINITION ---------------------------%
%
% Reference origin for moment computation
REF_ORIGIN_MOMENT_X = 0.248
REF_ORIGIN_MOMENT_Y = 0.00
REF_ORIGIN_MOMENT_Z = 0.00
%
% Reference length for pitching, rolling, and yawing non-dimensional moment
REF_LENGTH= 1.0
%
% Reference area for force coefficients (0 implies automatic calculation)
REF_AREA= 1.0

% ----------------------- BOUNDARY CONDITION DEFINITION -----------------------%
%
% Marker of the Euler boundary (0 = no marker)
MARKER_EULER= ( airfoil )
%
% Marker of the far field (0 = no marker)
MARKER_FAR= ( farfield )

% ------------------------ SURFACES IDENTIFICATION ----------------------------%
%
% Marker(s) of the surface in the surface flow solution file
MARKER_PLOTTING = ( airfoil )
%
% Marker(s) of the surface where the non-dimensional coefficients are evaluated.
MARKER_MONITORING = ( airfoil )
%
% 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= 100.0
%
% 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, 1.0, 1e10 )
%
% Runge-Kutta alpha coefficients
RK_ALPHA_COEFF= ( 0.66667, 0.66667, 1.000000 )
%

% ------------------------ 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= 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= 10

% -------------------------- 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 PreSmoothing Level
MG_PRE_SMOOTH= ( 1, 2, 3, 3 )
%
% Multi-Grid PostSmoothing 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= 0.9
%
% Damping factor for the correction prolongation
MG_DAMP_PROLONGATION= 0.9

% -------------------- FLOW NUMERICAL METHOD DEFINITION -----------------------%
%
% Convective numerical method (JST, LAX-FRIEDRICH, CUSP, ROE, AUSM, HLLC,
% TURKEL_PREC, MSW)
CONV_NUM_METHOD_FLOW= SLAU2
%
% Allows much higher CFL
USE_ACCURATE_FLUX_JACOBIANS=YES
%
% Monotonic Upwind Scheme for Conservation Laws (TVD) in the flow equations.
% Required for 2nd order upwind schemes (NO, YES)
MUSCL_FLOW= YES
%
% Slope limiter (VENKATAKRISHNAN, MINMOD)
SLOPE_LIMITER_FLOW= VENKATAKRISHNAN_WANG
%
% Coefficient for the limiter (smooth regions)
VENKAT_LIMITER_COEFF= 0.05
%
% 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

% ---------------- 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)
OBJECTIVE_FUNCTION= DRAG
%
% Convective numerical method (JST, LAX-FRIEDRICH, ROE)
CONV_NUM_METHOD_ADJFLOW= SLAU2
%
% Monotonic Upwind Scheme for Conservation Laws (TVD) in the adjoint flow equations.
% Required for 2nd order upwind schemes (NO, YES)
MUSCL_ADJFLOW= YES
%
% Slope limiter (NONE, VENKATAKRISHNAN, BARTH_JESPERSEN, VAN_ALBADA_EDGE,
% SHARP_EDGES, WALL_DISTANCE)
SLOPE_LIMITER_ADJFLOW= VENKATAKRISHNAN_WANG
%
% 2nd, and 4th order artificial dissipation coefficients
ADJ_JST_SENSOR_COEFF= ( 0.5, 0.02 )
%
% Reduction factor of the CFL coefficient in the adjoint problem
CFL_REDUCTION_ADJFLOW= 0.8
%
% Time discretization (RUNGE-KUTTA_EXPLICIT, EULER_IMPLICIT)
TIME_DISCRE_ADJFLOW= EULER_IMPLICIT
%
% Adjoint frozen viscosity (NO, YES)
FROZEN_VISC_CONT= YES

% ----------------------- GEOMETRY EVALUATION PARAMETERS ----------------------%
%
% Marker(s) of the surface where geometrical based function will be evaluated
GEO_MARKER= ( airfoil )
%
% Description of the geometry to be analyzed (AIRFOIL, WING, FUSELAGE)
GEO_DESCRIPTION= AIRFOIL
%
% Geometrical evaluation mode (FUNCTION, GRADIENT)
GEO_MODE= FUNCTION

% ------------------------ GRID DEFORMATION PARAMETERS ------------------------%
% Kind of deformation (FFD_SETTING, 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= 0.0

% --------------------------- CONVERGENCE PARAMETERS --------------------------%
% Convergence criteria (CAUCHY, RESIDUAL)
%
CONV_CRITERIA= RESIDUAL
%
%
% Min value of the residual (log10 of the residual)
CONV_RESIDUAL_MINVAL= -10
%
% Start Cauchy 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
%

% ------------------------- INPUT/OUTPUT INFORMATION --------------------------%
%
% Mesh input file
MESH_FILENAME= 2Dmeshgap.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= restart_flow.dat
%
% Output file format (PARAVIEW, TECPLOT, STL)
OUTPUT_FILES = PARAVIEW_ASCII
%
% 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= pitchscramsupersonic
%
% 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
%
% Writing solution file frequency
OUTPUT_WRT_FREQ= 250
%

% --------------------- OPTIMAL SHAPE DESIGN DEFINITION -----------------------%
%
% Available flow based objective functions or constraint functions
% DRAG, LIFT, SIDEFORCE, EFFICIENCY, BUFFET,
% FORCE_X, FORCE_Y, FORCE_Z,
% MOMENT_X, MOMENT_Y, MOMENT_Z,
% THRUST, TORQUE, FIGURE_OF_MERIT,
% EQUIVALENT_AREA, NEARFIELD_PRESSURE,
% TOTAL_HEATFLUX, MAXIMUM_HEATFLUX,
% INVERSE_DESIGN_PRESSURE, INVERSE_DESIGN_HEATFLUX,
% SURFACE_TOTAL_PRESSURE, SURFACE_MASSFLOW
% SURFACE_STATIC_PRESSURE, SURFACE_MACH
%
% Available geometrical based objective functions or constraint functions
% AIRFOIL_AREA, AIRFOIL_THICKNESS, AIRFOIL_CHORD, AIRFOIL_TOC, AIRFOIL_AOA,
% WING_VOLUME, WING_MIN_THICKNESS, WING_MAX_THICKNESS, WING_MAX_CHORD, WING_MIN_TOC, WING_MAX_TWIST, WING_MAX_CURVATURE, WING_MAX_DIHEDRAL
% STATION#_WIDTH, STATION#_AREA, STATION#_THICKNESS, STATION#_CHORD, STATION#_TOC,
% STATION#_TWIST (where # is the index of the station defined in GEO_LOCATION_STATIONS)
%
% Available design variables
% 2D Design variables
% FFD_CONTROL_POINT_2D ( 19, Scale | Mark. List | FFD_BoxTag, i_Ind, j_Ind, x_Mov, y_Mov )
% FFD_CAMBER_2D ( 20, Scale | Mark. List | FFD_BoxTag, i_Ind )
% FFD_THICKNESS_2D ( 21, Scale | Mark. List | FFD_BoxTag, i_Ind )
% FFD_TWIST_2D ( 22, Scale | Mark. List | FFD_BoxTag, x_Orig, y_Orig )
% HICKS_HENNE ( 30, Scale | Mark. List | Lower(0)/Upper(1) side, x_Loc )
% ANGLE_OF_ATTACK ( 101, Scale | Mark. List | 1.0 )
%
% 3D Design variables
% FFD_CONTROL_POINT ( 11, Scale | Mark. List | FFD_BoxTag, i_Ind, j_Ind, k_Ind, x_Mov, y_Mov, z_Mov )
% FFD_NACELLE ( 12, Scale | Mark. List | FFD_BoxTag, rho_Ind, theta_Ind, phi_Ind, rho_Mov, phi_Mov )
% FFD_GULL ( 13, Scale | Mark. List | FFD_BoxTag, j_Ind )
% FFD_CAMBER ( 14, Scale | Mark. List | FFD_BoxTag, i_Ind, j_Ind )
% FFD_TWIST ( 15, Scale | Mark. List | FFD_BoxTag, j_Ind, x_Orig, y_Orig, z_Orig, x_End, y_End, z_End )
% FFD_THICKNESS ( 16, Scale | Mark. List | FFD_BoxTag, i_Ind, j_Ind )
% FFD_ROTATION ( 18, Scale | Mark. List | FFD_BoxTag, x_Axis, y_Axis, z_Axis, x_Turn, y_Turn, z_Turn )
% FFD_ANGLE_OF_ATTACK ( 24, Scale | Mark. List | FFD_BoxTag, 1.0 )
%
% Global design variables
% TRANSLATION ( 1, Scale | Mark. List | x_Disp, y_Disp, z_Disp )
% ROTATION ( 2, Scale | Mark. List | x_Axis, y_Axis, z_Axis, x_Turn, y_Turn, z_Turn )

% Optimization objective function with optional scaling factor
% ex= Objective * Scale
OPT_OBJECTIVE= DRAG * 0.001

% Optimization constraint functions with scaling factors, separated by semicolons
% ex= (Objective = Value ) * Scale, use '>','<','='
OPT_CONSTRAINT= ( LIFT = 0.0 ) * 0.001; ( AREA > 0.0660957 ) * 0.001
%
% List of design variables (Design variables are separated by semicolons)
DEFINITION_DV= ( 30, 1.0 | airfoil | 0, 0.961538461538 ); ( 30, 1.0 | airfoil | 0, 0.923076923077 ); ( 30, 1.0 | airfoil | 0, 0.884615384615 ); ( 30, 1.0 | airfoil | 0, 0.846153846154 ); ( 30, 1.0 | airfoil | 0, 0.807692307692 ); ( 30, 1.0 | airfoil | 0, 0.769230769231 ); ( 30, 1.0 | airfoil | 0, 0.730769230769 ); ( 30, 1.0 | airfoil | 0, 0.692307692308 ); ( 30, 1.0 | airfoil | 0, 0.653846153846 ); ( 30, 1.0 | airfoil | 0, 0.615384615385 ); ( 30, 1.0 | airfoil | 0, 0.576923076923 ); ( 30, 1.0 | airfoil | 0, 0.538461538462 ); ( 30, 1.0 | airfoil | 0, 0.5 ); ( 30, 1.0 | airfoil | 0, 0.461538461538 ); ( 30, 1.0 | airfoil | 0, 0.423076923077 ); ( 30, 1.0 | airfoil | 0, 0.384615384615 ); ( 30, 1.0 | airfoil | 0, 0.346153846154 ); ( 30, 1.0 | airfoil | 0, 0.307692307692 ); ( 30, 1.0 | airfoil | 0, 0.269230769231 ); ( 30, 1.0 | airfoil | 0, 0.230769230769 ); ( 30, 1.0 | airfoil | 0, 0.192307692308 ); ( 30, 1.0 | airfoil | 0, 0.153846153846 ); ( 30, 1.0 | airfoil | 0, 0.115384615385 ); ( 30, 1.0 | airfoil | 0, 0.0769230769231 ); ( 30, 1.0 | airfoil | 0, 0.0384615384615 ); ( 30, 1.0 | airfoil | 1, 0.0384615384615 ); ( 30, 1.0 | airfoil | 1, 0.0769230769231 ); ( 30, 1.0 | airfoil | 1, 0.115384615385 ); ( 30, 1.0 | airfoil | 1, 0.153846153846 ); ( 30, 1.0 | airfoil | 1, 0.192307692308 ); ( 30, 1.0 | airfoil | 1, 0.230769230769 ); ( 30, 1.0 | airfoil | 1, 0.269230769231 ); ( 30, 1.0 | airfoil | 1, 0.307692307692 ); ( 30, 1.0 | airfoil | 1, 0.346153846154 ); ( 30, 1.0 | airfoil | 1, 0.384615384615 ); ( 30, 1.0 | airfoil | 1, 0.423076923077 ); ( 30, 1.0 | airfoil | 1, 0.461538461538 ); ( 30, 1.0 | airfoil | 1, 0.5 ); ( 30, 1.0 | airfoil | 1, 0.538461538462 ); ( 30, 1.0 | airfoil | 1, 0.576923076923 ); ( 30, 1.0 | airfoil | 1, 0.615384615385 ); ( 30, 1.0 | airfoil | 1, 0.653846153846 ); ( 30, 1.0 | airfoil | 1, 0.692307692308 ); ( 30, 1.0 | airfoil | 1, 0.730769230769 ); ( 30, 1.0 | airfoil | 1, 0.769230769231 ); ( 30, 1.0 | airfoil | 1, 0.807692307692 ); ( 30, 1.0 | airfoil | 1, 0.846153846154 ); ( 30, 1.0 | airfoil | 1, 0.884615384615 ); ( 30, 1.0 | airfoil | 1, 0.923076923077 ); ( 30, 1.0 | airfoil | 1, 0.961538461538 )


If anyone has any advice on how to resolve this convergence issue, that would be great!!
Thanks,
William
Hi there,

Based on your config file here is what I would recommend:

1. I don't know how fine or course your mesh is but CFL 100 is a big number.
Turn off the CFL adaptation and set CFL to 4 if you got a course mesh and 1 if you have a not-very fine mesh --- Later if your convergence issue resolved you may test to see how big you may go with CFL adaptation.

Then see if turning off CFL adaption and setting to smaller value could solve your problem. If it didn't solve your problem which it ain't go to the next step.

2. set your convective scheme to LAX that is inherently a first order accurate scheme. You will problem will not have a convergence issue with this one. If you had then idw what your problem could possibly be. If you didn't have convergence issue with LAX then the issue is because of the physics of your problem you need to tune your central or upwind convective scheme you are using. Here is the link to SU2 webpage explaining its convective schemes:
https://su2code.github.io/docs_v7/Convective-Schemes/

3. If you had no problem with LAX pick ROE as your convective scheme and turn off MUSCLE to see if you have no convergence issue. If you still had convergence issue then you might use ROE_LOW_DISSIPATION and ENTROPY_FIX_COEFF to make it work.

4. At last when you had no problem convergence issue with LAX and ROE you may switch to JST and use CENTRAL_JACOBIAN_FIX_FACTOR and JST_SENSOR_COEFF = (2nd, 4th) to make it work. For CENTRAL_JACOBIAN_FIX_FACTOR I guess 1 could work for you. For JST_SENSOR_COEFF = (2nd, 4th) default values (0.5, 0.02) are recommended.

Good luck,
Pay
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Old   February 5, 2021, 05:55
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William Haigh
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Hi Pay,
Unfortunately, I have tried every option that you mentionned and none of them allowed convergence.
Should I try to make the mesh very coarse and see if I can get closer to convergence?
I am surprised that the code worked perfectly fine for low speed flows but does not want to work for that supersonic condition.
Can you think of any other possible solutions to achieve convergence?
Thanks for all of your help!
William
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Old   February 5, 2021, 06:19
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Pay D.
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Quote:
Originally Posted by WilliamH View Post
Hi Pay,
Unfortunately, I have tried every option that you mentionned and none of them allowed convergence.
Should I try to make the mesh very coarse and see if I can get closer to convergence?
I am surprised that the code worked perfectly fine for low speed flows but does not want to work for that supersonic condition.
Can you think of any other possible solutions to achieve convergence?
Thanks for all of your help!
William
Sorry to hear that. If I were you, I would use a course mesh, a small time step and LAX. No CFL adaptation, no multigrid! This should work!
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