[Nicles43]

Hi

I am trying for many days to make a simulation for a re-entry bluff body, an Apollo like capsule, at hypersonic velocity.

My intial goal was to study it at h = 38 km, Mach = 5, with air-5 model for air, p and T found in internet for 38 km altitude.

However, simulation was not converging. So i decided to consider at first a subsonic mach, Mach = 0.5, at the same altitude of 38 km. HOwvwer, still the simulation is not converging.

I am wondering many questions:
- why the simulation starts only with AUSM scheme? WHen i try to use ASUM+UP or AUSM+M , the simulation does not make any iteration, displaying "SU2 has diverged"


-what is my possible error? I have done so many tentatives. There is an error on the mesh? My mesh is a fully unstrcutred one, with smaller elements near the capsule. Myabe, i am putting something worng inside the config?


Here, below, i will copy the config and the mesh.geo texts

I will attach some images about: mesh and results of the simulation.



This is the config: -------------------------------------------------------------------------------
SOLVER= NEMO_EULER
MATH_PROBLEM= DIRECT
RESTART_SOL= NO
READ_BINARY_RESTART= NO
TIME_DOMAIN= NO
%
FROZEN_MIXTURE=NO
TRANSPORT_COEFF_MODEL = CHAPMANN-ENSKOG
KIND_TURB_MODEL= NONE
%
FLUID_MODEL= MUTATIONPP
GAS_MODEL= air_5
GAS_COMPOSITION= (0.0, 0.0, 0.00, 0.79, 0.21)
%
% Reference origin for moment computation : CG coordinates
REF_ORIGIN_MOMENT_X = 1.1455
REF_ORIGIN_MOMENT_Y = 0.1600
REF_ORIGIN_MOMENT_Z = 0.00
%
% Reference length for pitching, rolling, and yawing non-dimensional moment
REF_LENGTH= 3.9116
%
% Reference area for force coefficients (0 implies automatic calculation)
REF_AREA= 12.020
%
INIT_OPTION= TD_CONDITIONS
MACH_NUMBER= 0.5
AOA= 0.0
FREESTREAM_PRESSURE= 377.1
FREESTREAM_TEMPERATURE= 244.8
FREESTREAM_TEMPERATURE_VE= 244.8
%
MARKER_FAR = ( FARFIELD )
MARKER_EULER = ( CAPSULE )
%
MARKER_PLOTTING= ( CAPSULE )
MARKER_MONITORING= ( CAPSULE )
%
ITER= 1000000

NUM_METHOD_GRAD= WEIGHTED_LEAST_SQUARES

CFL_NUMBER= 0.05

%
CFL_ADAPT= YES
%
CFL_ADAPT_PARAM= (0.0005, 1.0005, 0, 1)

RK_ALPHA_COEFF= ( 0.66667, 0.66667, 1.000000 )

LINEAR_SOLVER= BCGSTAB

LINEAR_SOLVER_ERROR= 1E-6

LINEAR_SOLVER_ITER= 5

%
CONV_NUM_METHOD_FLOW= AUSM

MUSCL_FLOW= NO
SLOPE_LIMITER_FLOW= VENKATAKRISHNAN_WANG
VENKAT_LIMITER_COEFF= 0.01

TIME_DISCRE_FLOW= EULER_EXPLICIT
%

% Min value of the residual (log10 of the residual)
CONV_RESIDUAL_MINVAL= -50
%
MESH_FILENAME= apoll.su2
MESH_FORMAT= SU2
TABULAR_FORMAT= CSV
SOLUTION_FILENAME= restart_flow5_nemo.dat
%OUTPUT_FILES= (RESTART_ASCII, PARAVIEW, SURFACE_PARAVIEW)
CONV_FILENAME= history5_nemo
RESTART_FILENAME= restart_flow5_nemo
VOLUME_FILENAME= soln_volume5_nemo
SURFACE_FILENAME= soln_surface5_nemo

OUTPUT_WRT_FREQ= 1000
SCREEN_WRT_FREQ_TIME= 100
SCREEN_WRT_FREQ_OUTER= 100
SCREEN_OUTPUT= (INNER_ITER, RMS_DENSITY_4, RMS_DENSITY_5, RMS_ENERGY, RMS_ENERGY_VE, DRAG, CAUCHY_DRAG)

VOLUME_OUTPUT= (COORDINATES, SOLUTION, PRIMITIVE, AUXILIARY, RESIDUAL)

HISTORY_OUTPUT= (ITER, RMS_RES, CFL_NUMBER)
-----------------------------------------------------------------------------------------------



This is my geo file: ---------------------------------------



H = 0.75;
h = 0.0075;
R = 80;

//CAPSULE

Point(1) = {0.3743, 1.8368, 0, h};
//+
Point(2) = {0.3743, -1.8368, 0, h};
//+
Point(3) = {0.5543, 1.9558, 0, h};
//+
Point(4) = {0.5543, -1.9558, 0, h};
//+
Point(5) = {3.3254, 0.1938, 0, h};
//+
Point(6) = {3.3254, -0.1938, 0, h};
//+
Point(7) = {3.4306, 0, 0, h};
//+
Point(8) = {0.554227, 1.760289, 0, h};
//+
Point(9) = {0.554227, -1.760289, 0, h};
//+
Point(10) = {3.1995, 0, 0, h};
//+
Point(11) = {4.6939, 0, 0, h};
//+
Point(12) = {0.6608, 1.9242, 0, h};
//+
Point(13) = {0.6608, -1.9242, 0, h};
//+
//+
Circle(1) = {1, 8, 12};
//+
Circle(2) = {2, 9, 13};
//+
Circle(3) = {5, 10, 6};
//+
Circle(4) = {1, 11, 2};
//+
Line(5) = {12, 5};
//+
Line(6) = {6, 13};


//FARFIELD

Point(15) = {R+30, 0, 0, H};
Point(16) = {30, R, 0, H};
Point(17) = {-R+30, 0, 0, H};
Point(18) = {30, -R, 0, H};

// farfield center
Point(19) = {30,0,0,H};

Circle(7) = {15, 19, 16};
Circle(8) = {16, 19, 17};
Circle(9) = {17, 19, 18};
Circle(10) = {18, 19, 15};
Physical Curve("CAPSULE", 1) = {5, 1, 4, 2, 6, 3};
//+
Physical Curve("FARFIELD", 2) = {7, 8, 9, 10};
Curve Loop(1) = {8, 9, 10, 7};
//+
Curve Loop(2) = {1, 5, 3, 6, -2, -4};
//+
Plane Surface(1) = {1, 2};
//+
Physical Surface("VOLUME", 1) = {1};
---------------------------------------------------------------------

[aeroshiva7]

Originally Posted by Nicles43

Hi

I am trying for many days to make a simulation for a re-entry bluff body, an Apollo like capsule, at hypersonic velocity.

My intial goal was to study it at h = 38 km, Mach = 5, with air-5 model for air, p and T found in internet for 38 km altitude.

However, simulation was not converging. So i decided to consider at first a subsonic mach, Mach = 0.5, at the same altitude of 38 km. HOwvwer, still the simulation is not converging.

I am wondering many questions:
- why the simulation starts only with AUSM scheme? WHen i try to use ASUM+UP or AUSM+M , the simulation does not make any iteration, displaying "SU2 has diverged"


-what is my possible error? I have done so many tentatives. There is an error on the mesh? My mesh is a fully unstrcutred one, with smaller elements near the capsule. Myabe, i am putting something worng inside the config?


Here, below, i will copy the config and the mesh.geo texts

I will attach some images about: mesh and results of the simulation.



This is the config: -------------------------------------------------------------------------------
SOLVER= NEMO_EULER
MATH_PROBLEM= DIRECT
RESTART_SOL= NO
READ_BINARY_RESTART= NO
TIME_DOMAIN= NO
%
FROZEN_MIXTURE=NO
TRANSPORT_COEFF_MODEL = CHAPMANN-ENSKOG
KIND_TURB_MODEL= NONE
%
FLUID_MODEL= MUTATIONPP
GAS_MODEL= air_5
GAS_COMPOSITION= (0.0, 0.0, 0.00, 0.79, 0.21)
%
% Reference origin for moment computation : CG coordinates
REF_ORIGIN_MOMENT_X = 1.1455
REF_ORIGIN_MOMENT_Y = 0.1600
REF_ORIGIN_MOMENT_Z = 0.00
%
% Reference length for pitching, rolling, and yawing non-dimensional moment
REF_LENGTH= 3.9116
%
% Reference area for force coefficients (0 implies automatic calculation)
REF_AREA= 12.020
%
INIT_OPTION= TD_CONDITIONS
MACH_NUMBER= 0.5
AOA= 0.0
FREESTREAM_PRESSURE= 377.1
FREESTREAM_TEMPERATURE= 244.8
FREESTREAM_TEMPERATURE_VE= 244.8
%
MARKER_FAR = ( FARFIELD )
MARKER_EULER = ( CAPSULE )
%
MARKER_PLOTTING= ( CAPSULE )
MARKER_MONITORING= ( CAPSULE )
%
ITER= 1000000

NUM_METHOD_GRAD= WEIGHTED_LEAST_SQUARES

CFL_NUMBER= 0.05

%
CFL_ADAPT= YES
%
CFL_ADAPT_PARAM= (0.0005, 1.0005, 0, 1)

RK_ALPHA_COEFF= ( 0.66667, 0.66667, 1.000000 )

LINEAR_SOLVER= BCGSTAB

LINEAR_SOLVER_ERROR= 1E-6

LINEAR_SOLVER_ITER= 5

%
CONV_NUM_METHOD_FLOW= AUSM

MUSCL_FLOW= NO
SLOPE_LIMITER_FLOW= VENKATAKRISHNAN_WANG
VENKAT_LIMITER_COEFF= 0.01

TIME_DISCRE_FLOW= EULER_EXPLICIT
%

% Min value of the residual (log10 of the residual)
CONV_RESIDUAL_MINVAL= -50
%
MESH_FILENAME= apoll.su2
MESH_FORMAT= SU2
TABULAR_FORMAT= CSV
SOLUTION_FILENAME= restart_flow5_nemo.dat
%OUTPUT_FILES= (RESTART_ASCII, PARAVIEW, SURFACE_PARAVIEW)
CONV_FILENAME= history5_nemo
RESTART_FILENAME= restart_flow5_nemo
VOLUME_FILENAME= soln_volume5_nemo
SURFACE_FILENAME= soln_surface5_nemo

OUTPUT_WRT_FREQ= 1000
SCREEN_WRT_FREQ_TIME= 100
SCREEN_WRT_FREQ_OUTER= 100
SCREEN_OUTPUT= (INNER_ITER, RMS_DENSITY_4, RMS_DENSITY_5, RMS_ENERGY, RMS_ENERGY_VE, DRAG, CAUCHY_DRAG)

VOLUME_OUTPUT= (COORDINATES, SOLUTION, PRIMITIVE, AUXILIARY, RESIDUAL)

HISTORY_OUTPUT= (ITER, RMS_RES, CFL_NUMBER)
-----------------------------------------------------------------------------------------------



This is my geo file: ---------------------------------------



H = 0.75;
h = 0.0075;
R = 80;

//CAPSULE

Point(1) = {0.3743, 1.8368, 0, h};
//+
Point(2) = {0.3743, -1.8368, 0, h};
//+
Point(3) = {0.5543, 1.9558, 0, h};
//+
Point(4) = {0.5543, -1.9558, 0, h};
//+
Point(5) = {3.3254, 0.1938, 0, h};
//+
Point(6) = {3.3254, -0.1938, 0, h};
//+
Point(7) = {3.4306, 0, 0, h};
//+
Point(8) = {0.554227, 1.760289, 0, h};
//+
Point(9) = {0.554227, -1.760289, 0, h};
//+
Point(10) = {3.1995, 0, 0, h};
//+
Point(11) = {4.6939, 0, 0, h};
//+
Point(12) = {0.6608, 1.9242, 0, h};
//+
Point(13) = {0.6608, -1.9242, 0, h};
//+
//+
Circle(1) = {1, 8, 12};
//+
Circle(2) = {2, 9, 13};
//+
Circle(3) = {5, 10, 6};
//+
Circle(4) = {1, 11, 2};
//+
Line(5) = {12, 5};
//+
Line(6) = {6, 13};


//FARFIELD

Point(15) = {R+30, 0, 0, H};
Point(16) = {30, R, 0, H};
Point(17) = {-R+30, 0, 0, H};
Point(18) = {30, -R, 0, H};

// farfield center
Point(19) = {30,0,0,H};

Circle(7) = {15, 19, 16};
Circle(8) = {16, 19, 17};
Circle(9) = {17, 19, 18};
Circle(10) = {18, 19, 15};
Physical Curve("CAPSULE", 1) = {5, 1, 4, 2, 6, 3};
//+
Physical Curve("FARFIELD", 2) = {7, 8, 9, 10};
Curve Loop(1) = {8, 9, 10, 7};
//+
Curve Loop(2) = {1, 5, 3, 6, -2, -4};
//+
Plane Surface(1) = {1, 2};
//+
Physical Surface("VOLUME", 1) = {1};
---------------------------------------------------------------------

i can do this in Ansys Fluent, if you are looking solution with fluent you may connect me at aeroshivakumar@gmail.com

[Nicles43]

Originally Posted by aeroshiva7

i can do this in Ansys Fluent, if you are looking solution with fluent you may connect me at aeroshivakumar@gmail.com

HI,



i obtain a solution simply reducing the external domain length from 80 to 40.
However, i reach convergence only for a first order case. WHen i try second order scheme wtih AUSM, no convergence is reached.
THe simulation is done in su2 (nemo), no ansis. I don't know how this software works

[aeroshiva7]

Originally Posted by Nicles43

HI,



i obtain a solution simply reducing the external domain length from 80 to 40.
However, i reach convergence only for a first order case. WHen i try second order scheme wtih AUSM, no convergence is reached.
THe simulation is done in su2 (nemo), no ansis. I don't know how this software works

Ansys Fluent is best Software's i can give you best converged solution, and validation of data too