CFD Online Discussion Forums (https://www.cfd-online.com/Forums/)
-   SU2 (https://www.cfd-online.com/Forums/su2/)
-   -   Rising residual behaviour and convergence (https://www.cfd-online.com/Forums/su2/208213-rising-residual-behaviour-convergence.html)

 tjim October 12, 2018 05:04

Rising residual behaviour and convergence

5 Attachment(s)
Hi all,

Can anyone help me identify if the following Euler run has converged? While the CL, CD, CFz, etc. all seem to show a converged result, it is the first simulation I have seen where Res_Flow[0] – Res_Flow[4] (one attached for illustration) starts with a low residual and converges to a higher one.

Is this a Is this physicallly valid convergence? I have also pasted the contents of my configuration file below, in case I have made a simple error in my setup. I could only upload 5 files so I chose a few different plots to show what appears to be converged values. The Res_Flow values look suspicious though!

Also, what exactly are Res_Flow[0-4]? I saw another post suggesting one to look in the FAQ. While the link given doesn't work anymore, I presume it now should point to https://su2code.github.io/docs/FAQ/. The page mentions Residual[0] and Primitive[0] but not Res_Flow[0] etc. Are they just renamed variables?

```% ------------- DIRECT, ADJOINT, AND LINEARIZED PROBLEM DEFINITION ------------% % % Physical governing equations (EULER, NAVIER_STOKES) PHYSICAL_PROBLEM= EULER % % Mathematical problem (DIRECT, CONTINUOUS_ADJOINT) MATH_PROBLEM= DIRECT % % Restart solution (NO, YES) RESTART_SOL= NO % % Write binary restart files (YES, NO) WRT_BINARY_RESTART= NO % % Read binary restart files (YES, NO) READ_BINARY_RESTART= NO % -------------------- COMPRESSIBLE FREE-STREAM DEFINITION --------------------% % % Mach number (non-dimensional, based on the free-stream values) MACH_NUMBER= 1.7 % % 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 for Euler equations) FREESTREAM_PRESSURE= 9119.83 % % Free-stream temperature (288.15 K by default) FREESTREAM_TEMPERATURE= 216.65 % ---------------------- REFERENCE VALUE DEFINITION ---------------------------% % % Reference origin for moment computation REF_ORIGIN_MOMENT_X = 0.25 REF_ORIGIN_MOMENT_Y = 0.00 REF_ORIGIN_MOMENT_Z = 0.00 % % Reference length for pitching, rolling, and yaMAIN_BOX non-dimensional moment REF_LENGTH= 1.0 % % Reference area for force coefficients (0 implies automatic calculation) REF_AREA= 0 % % Flow non-dimensionalization (DIMENSIONAL, FREESTREAM_PRESS_EQ_ONE, %                              FREESTREAM_VEL_EQ_MACH, FREESTREAM_VEL_EQ_ONE) REF_DIMENSIONALIZATION= FREESTREAM_VEL_EQ_ONE % ----------------------- BOUNDARY CONDITION DEFINITION -----------------------% % % Marker of the Euler boundary (0 implies no marker) MARKER_EULER= ( BODY ) % % Marker of the far field (0 implies no marker) MARKER_FAR= ( quad_FARFIELD, tri_FARFIELD ) % % Marker of symmetry boundary (0 implies no marker) MARKER_SYM= ( quad_SYMMETRY, tri_SYMMETRY ) % ------------------------ SURFACES IDENTIFICATION ----------------------------% % % Marker(s) of the surface in the surface flow solution file MARKER_PLOTTING = ( BODY ) % % Marker(s) of the surface where the non-dimensional coefficients are evaluated. MARKER_MONITORING = ( BODY ) % % Marker(s) of the surface where obj. func. (design problem) will be evaluated MARKER_DESIGNING = ( BODY ) % ------------- COMMON PARAMETERS TO DEFINE THE NUMERICAL METHOD --------------% % % Numerical method for spatial gradients (GREEN_GAUSS, WEIGHTED_LEAST_SQUARES) NUM_METHOD_GRAD= WEIGHTED_LEAST_SQUARES % % Objective function in gradient evaluation  (DRAG, LIFT, SIDEFORCE, MOMENT_X, %                                            MOMENT_Y, MOMENT_Z, EFFICIENCY, %                                            EQUIVALENT_AREA, NEARFIELD_PRESSURE, %                                            FORCE_X, FORCE_Y, FORCE_Z, THRUST, %                                            TORQUE, FREE_SURFACE, TOTAL_HEATFLUX, %                                            MAXIMUM_HEATFLUX, INVERSE_DESIGN_PRESSURE, %                                            INVERSE_DESIGN_HEATFLUX) OBJECTIVE_FUNCTION= DRAG % % Courant-Friedrichs-Lewy condition of the finest grid CFL_NUMBER= 5.0 % % 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= ( 1.5, 0.5, 1.0, 100.0 ) % % Runge-Kutta alpha coefficients RK_ALPHA_COEFF= ( 0.66667, 0.66667, 1.000000 ) % % Number of total iterations EXT_ITER= 99999 % % Linear solver for the implicit formulation (BCGSTAB, FGMRES) LINEAR_SOLVER= FGMRES % % Preconditioner of the Krylov linear solver (ILU, LU_SGS, LINELET, JACOBI) LINEAR_SOLVER_PREC= LU_SGS % % 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= 2 % ----------------------- SLOPE LIMITER DEFINITION ----------------------------% % % Coefficient for the limiter VENKAT_LIMITER_COEFF= 0.03 % % Coefficient for the sharp edges limiter ADJ_SHARP_LIMITER_COEFF= 3.0 % % Reference coefficient (sensitivity) for detecting sharp edges. REF_SHARP_EDGES= 3.0 % % Remove sharp edges from the sensitivity evaluation (NO, YES) SENS_REMOVE_SHARP= YES % -------------------------- MULTIGRID PARAMETERS -----------------------------% % % Multi-Grid Levels (0 = no multi-grid) MGLEVEL= 3 % % 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= JST % % Monotonic Upwind Scheme for Conservation Laws (TVD) in the flow equations. %          Required for 2nd order upwind schemes (NO, YES) MUSCL_FLOW= YES % % Slope limiter (NONE, VENKATAKRISHNAN, VENKATAKRISHNAN_WANG, %                BARTH_JESPERSEN, VAN_ALBADA_EDGE) SLOPE_LIMITER_FLOW= NONE % % 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 -------------------% % % Convective numerical method (JST, LAX-FRIEDRICH, ROE) CONV_NUM_METHOD_ADJFLOW= JST % % 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= NONE % % 2nd, and 4th order artificial dissipation coefficients ADJ_JST_SENSOR_COEFF= ( 0.0, 0.02 ) % % Reduction factor of the CFL coefficient in the adjoint problem CFL_REDUCTION_ADJFLOW= 0.5 % % Time discretization (RUNGE-KUTTA_EXPLICIT, EULER_IMPLICIT) TIME_DISCRE_ADJFLOW= EULER_IMPLICIT % --------------------------- CONVERGENCE PARAMETERS --------------------------& % % Convergence criteria (CAUCHY, RESIDUAL) CONV_CRITERIA= RESIDUAL % % Residual reduction (order of magnitude with respect to the initial value) RESIDUAL_REDUCTION= 8 % % Min value of the residual (log10 of the residual) RESIDUAL_MINVAL= -12 % % Start convergence criteria at iteration number STARTCONV_ITER= 25 % % Number of elements to apply the criteria CAUCHY_ELEMS= 100 % % Epsilon to control the series convergence CAUCHY_EPS= 1E-10 % % Function to apply the criteria (LIFT, DRAG, NEARFIELD_PRESS, SENS_GEOMETRY, %                                            SENS_MACH, DELTA_LIFT, DELTA_DRAG) CAUCHY_FUNC_FLOW= DRAG % ------------------------- INPUT/OUTPUT INFORMATION --------------------------% % % Mesh input file MESH_FILENAME= ../1_mesh/delta-split-mixed-000a-170m-156s-bc-adf.cgns % % Mesh output file MESH_OUT_FILENAME= mesh_out.su2 % % Restart flow input file SOLUTION_FLOW_FILENAME= solution_flow.dat % % Restart adjoint input file SOLUTION_ADJ_FILENAME= solution_adj.dat % % Mesh input file format (SU2) MESH_FORMAT= CGNS % % Output file format (PARAVIEW, TECPLOT) OUTPUT_FORMAT= PARAVIEW % % Output file convergence history CONV_FILENAME= history % % Output file restart flow RESTART_FLOW_FILENAME= restart_flow.dat % % Output file restart adjoint RESTART_ADJ_FILENAME= restart_adj.dat % % Output file flow (w/o extension) variables VOLUME_FLOW_FILENAME= flow % % 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_FLOW_FILENAME= surface_flow % % Output file surface adjoint coefficient (w/o extension) SURFACE_ADJ_FILENAME= surface_adjoint % % Writing solution frequency WRT_SOL_FREQ= 100 % % Writing convergence history frequency WRT_CON_FREQ= 1```