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May 26, 2023, 11:43 
su2 nemo divergence hypersonic apollo

#1 
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Nicola Trippella
Join Date: May 2023
Location: Milan
Posts: 14
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Hi
I am trying for many days to make a simulation for a reentry bluff body, an Apollo like capsule, at hypersonic velocity. My intial goal was to study it at h = 38 km, Mach = 5, with air5 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 = CHAPMANNENSKOG 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 nondimensional 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= 1E6 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};  

May 29, 2023, 02:47 

#2  
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shiva kumar
Join Date: Aug 2021
Posts: 31
Rep Power: 4 
Quote:
i can do this in Ansys Fluent, if you are looking solution with fluent you may connect me at aeroshivakumar@gmail.com 

May 29, 2023, 06:00 
second order accuracy problem

#3  
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Nicola Trippella
Join Date: May 2023
Location: Milan
Posts: 14
Rep Power: 2 
Quote:
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 

May 30, 2023, 09:21 

#4  
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shiva kumar
Join Date: Aug 2021
Posts: 31
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apollo, convergence, hypersonic, nemo, su2 
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