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Old   March 24, 2015, 12:09
Default 2d ffd
  #1
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Hi to everyone. I'm trying to solve the tutorial i found in testcases about the Euler steady NACA0012 with FFD. The problem is that when i generate the FFD box the SU2_DEF automatically creates control points with z non costant component:
FFD_CONTROL_POINTS= 24
0 0 0 0 -0.08 -0.5
0 0 1 0 -0.08 0.5
0 1 0 0 0.08 -0.5
0 1 1 0 0.08 0.5
1 0 0 0.2 -0.08 -0.5
1 0 1 0.2 -0.08 0.5
1 1 0 0.2 0.08 -0.5
1 1 1 0.2 0.08 0.5
2 0 0 0.4 -0.08 -0.5
2 0 1 0.4 -0.08 0.5
2 1 0 0.4 0.08 -0.5
2 1 1 0.4 0.08 0.5
3 0 0 0.6 -0.08 -0.5
3 0 1 0.6 -0.08 0.5
3 1 0 0.6 0.08 -0.5
3 1 1 0.6 0.08 0.5
4 0 0 0.8 -0.08 -0.5
4 0 1 0.8 -0.08 0.5
4 1 0 0.8 0.08 -0.5
4 1 1 0.8 0.08 0.5
5 0 0 1 -0.08 -0.5
5 0 1 1 -0.08 0.5
5 1 0 1 0.08 -0.5
5 1 1 1 0.08 0.5
I can't understand where is the mistake. I'm using the mesh i found in the testcases. Sorry for my english,hope you understand the problem.
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Old   May 19, 2015, 16:41
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hlk
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Quote:
Originally Posted by Luca B View Post
Hi to everyone. I'm trying to solve the tutorial i found in testcases about the Euler steady NACA0012 with FFD. The problem is that when i generate the FFD box the SU2_DEF automatically creates control points with z non costant component:
FFD_CONTROL_POINTS= 24
0 0 0 0 -0.08 -0.5
0 0 1 0 -0.08 0.5
0 1 0 0 0.08 -0.5
0 1 1 0 0.08 0.5
1 0 0 0.2 -0.08 -0.5
1 0 1 0.2 -0.08 0.5
1 1 0 0.2 0.08 -0.5
1 1 1 0.2 0.08 0.5
2 0 0 0.4 -0.08 -0.5
2 0 1 0.4 -0.08 0.5
2 1 0 0.4 0.08 -0.5
2 1 1 0.4 0.08 0.5
3 0 0 0.6 -0.08 -0.5
3 0 1 0.6 -0.08 0.5
3 1 0 0.6 0.08 -0.5
3 1 1 0.6 0.08 0.5
4 0 0 0.8 -0.08 -0.5
4 0 1 0.8 -0.08 0.5
4 1 0 0.8 0.08 -0.5
4 1 1 0.8 0.08 0.5
5 0 0 1 -0.08 -0.5
5 0 1 1 -0.08 0.5
5 1 0 1 0.08 -0.5
5 1 1 1 0.08 0.5
I can't understand where is the mistake. I'm using the mesh i found in the testcases. Sorry for my english,hope you understand the problem.
Thanks for your question.
You have not made a mistake - this is how the FFD box is made in 2D. The mesh format assumes that for 2D the mesh is in the XY plane, and at "0" in the Z direction.
Please post again if there are further problems.
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Old   June 8, 2015, 09:30
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Thank you for your answer. I've done the optimization of the multi element profile with DRAG as objective function and some constrains using the FFD method. Now i'm trying to use LIFT as objective function on a single NACA0012 but it doesn't work. If i keep DRAG as objective function and i use a lift constrain to maximixe the vertical force it works well. Do you have any suggestions?Here i attach the .cfg with LIFT as obj funct.
% ------------- DIRECT, ADJOINT, AND LINEARIZED PROBLEM DEFINITION ------------%
%
% Physical governing equations (EULER, NAVIER_STOKES,
% TNE2_EULER, TNE2_NAVIER_STOKES,
% WAVE_EQUATION, HEAT_EQUATION, LINEAR_ELASTICITY,
% POISSON_EQUATION)
PHYSICAL_PROBLEM= EULER
%
%
% Mathematical problem (DIRECT, ADJOINT, LINEARIZED)
MATH_PROBLEM= DIRECT
%
% Restart solution (NO, YES)
RESTART_SOL= NO

% -------------------- COMPRESSIBLE FREE-STREAM DEFINITION --------------------%
%
% Mach number (non-dimensional, based on the free-stream values)
MACH_NUMBER= 0.8
%
% Angle of attack (degrees, only for compressible flows)
AoA= 1.25
%
% Free-stream temperature (288.15 K by default)
FREESTREAM_TEMPERATURE= 288.15
%
% Free-stream pressure (101325.0 N/m^2 by default, only Euler flows)
FREESTREAM_PRESSURE= 101325.0

% ---------------------- 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 yawing non-dimensional moment
REF_LENGTH_MOMENT= 1.0
%
% Reference area for force coefficients (0 implies automatic calculation)
REF_AREA= 1.0
%
% Reference pressure (101325.0 N/m^2 by default, only for compressible flows)
REF_PRESSURE= 1.0
%
% Reference temperature (273.15 K by default, only for compressible flows)
REF_TEMPERATURE= 1.0
%
% Reference density (1.2886 Kg/m^3 by default, only for compressible flows)
REF_DENSITY= 1.0
%

% -------------------- BOUNDARY CONDITION DEFINITION --------------------------%
%
% Navier-Stokes wall boundary marker(s) (NONE = no marker)
MARKER_EULER= ( airfoil )
%
% Farfield boundary marker(s) (NONE = no marker)
MARKER_FAR= ( farfield )
%
% Marker(s) of the surface to be plotted or designed
MARKER_PLOTTING= ( airfoil )
%
% Marker(s) of the surface where the functional (Cd, Cl, etc.) will be evaluated
MARKER_MONITORING= ( airfoil )

% ------------- COMMON PARAMETERS DEFINING THE NUMERICAL METHOD ---------------%
%
% Numerical method for spatial gradients (GREEN_GAUSS, WEIGHTED_LEAST_SQUARES)
%NUM_METHOD_GRAD= WEIGHTED_LEAST_SQUARES
NUM_METHOD_GRAD= GREEN_GAUSS
%
% Courant-Friedrichs-Lewy condition of the finest grid
CFL_NUMBER= 1
%
% 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= ( 2.0, 1.5, 0.0001, 20 )
%
% Number of total iterations
EXT_ITER= 99999
%
% Linear solver for the implicit formulation (BCGSTAB, FGMRES)
LINEAR_SOLVER= FGMRES
%
% Preconditioner of the Krylov linear solver (NONE, JACOBI, LINELET, LUSGS)
LINEAR_SOLVER_PREC= LU_SGS
%
% Min error of the linear solver for the implicit formulation
LINEAR_SOLVER_ERROR= 1E-4
%
% Max number of iterations of the linear solver for the implicit formulation
LINEAR_SOLVER_ITER= 5

% -------------------------- MULTIGRID PARAMETERS -----------------------------%
%
% Multi-Grid Levels (0 = no multi-grid)
MGLEVEL= 2
%
% Multi-Grid Cycle (V_CYCLE, W_CYCLE)
MGCYCLE= V_CYCLE
%
% Multigrid pre-smoothing level
MG_PRE_SMOOTH= ( 1, 2, 3, 3 )
%
% Multigrid post-smoothing level
MG_POST_SMOOTH= ( 2, 2, 2, 2 )
%
% Jacobi implicit smoothing of the correction
MG_CORRECTION_SMOOTH= ( 0, 0, 0, 0 )
%
% Damping factor for the residual restriction
MG_DAMP_RESTRICTION= 0.75
%
% Damping factor for the correction prolongation
MG_DAMP_PROLONGATION= 0.75
%

% -------------------- FLOW NUMERICAL METHOD DEFINITION -----------------------%
%
% Convective numerical method (JST, LAX-FRIEDRICH, CUSP, ROE, AUSM, HLLC,
% TURKEL_PREC, MSW)
CONV_NUM_METHOD_FLOW= JST
%
% Spatial numerical order integration (1ST_ORDER, 2ND_ORDER, 2ND_ORDER_LIMITER)
%
SPATIAL_ORDER_FLOW= 2ND_ORDER_LIMITER
%
% Slope limiter (VENKATAKRISHNAN, MINMOD)
SLOPE_LIMITER_FLOW= VENKATAKRISHNAN
%
% Coefficient for the limiter (smooth regions)
%LIMITER_COEFF= 10.0
%
% 1st, 2nd and 4th order artificial dissipation coefficients
AD_COEFF_FLOW= ( 0.15, 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, FREE_SURFACE)
OBJECTIVE_FUNCTION= LIFT
%
% Convective numerical method (JST, LAX-FRIEDRICH, ROE-1ST_ORDER,
% ROE-2ND_ORDER)
CONV_NUM_METHOD_ADJFLOW= JST
%
% Slope limiter (VENKATAKRISHNAN, SHARP_EDGES)
SLOPE_LIMITER_ADJFLOW= VENKATAKRISHNAN
%
% Coefficient for the sharp edges limiter
SHARP_EDGES_COEFF= 8.0
%
% 1st, 2nd, and 4th order artificial dissipation coefficients
AD_COEFF_ADJFLOW= ( 0.15, 0.0, 0.02 )
%
% Time discretization (RUNGE-KUTTA_EXPLICIT, EULER_IMPLICIT)
TIME_DISCRE_ADJFLOW= EULER_IMPLICIT
%
% Reduction factor of the CFL coefficient in the adjoint problem
CFL_REDUCTION_ADJFLOW= 0.8
%
% Limit value for the adjoint variable
LIMIT_ADJFLOW= 1E6
%
% Remove sharp edges from the sensitivity evaluation (NO, YES)
SENS_REMOVE_SHARP= YES
%
% Sensitivity smoothing (NONE, SOBOLEV, BIGRID)
SENS_SMOOTHING= NONE
%
% Multigrid adjoint problem (NO, YES)
MG_ADJFLOW= YES

% ----------------------- GEOMETRY EVALUATION PARAMETERS ----------------------%
%
% Geometrical evaluation mode (FUNCTION, GRADIENT)
GEO_MODE= FUNCTION
%
% Marker(s) of the surface where geometrical based func. will be evaluated
GEO_MARKER= (airfoil)

% -------------------- TURBULENT NUMERICAL METHOD DEFINITION ------------------%
%
% Convective numerical method (SCALAR_UPWIND)
%CONV_NUM_METHOD_TURB= SCALAR_UPWIND
%
% Spatial numerical order integration (1ST_ORDER, 2ND_ORDER, 2ND_ORDER_LIMITER)
%
%SPATIAL_ORDER_TURB= 1ST_ORDER
%
% Slope limiter (VENKATAKRISHNAN, MINMOD)
%SLOPE_LIMITER_TURB= VENKATAKRISHNAN
%
% Time discretization (EULER_IMPLICIT)
%TIME_DISCRE_TURB= EULER_IMPLICIT

% --------------------------- PARTITIONING STRATEGY ---------------------------%
% Write a tecplot/paraview file for each partition (NO, YES)
%VISUALIZE_PART= NO

% --------------------------- CONVERGENCE PARAMETERS --------------------------%
%
% Convergence criteria (CAUCHY, RESIDUAL)
%
CONV_CRITERIA= RESIDUAL
%
% Residual reduction (order of magnitude with respect to the initial value)
RESIDUAL_REDUCTION= 6
%
% Min value of the residual (log10 of the residual)
RESIDUAL_MINVAL= -8
%
% Start convergence criteria at iteration number
STARTCONV_ITER= 10
%
% Number of elements to apply the criteria
CAUCHY_ELEMS= 100
%
% Epsilon to control the series convergence
CAUCHY_EPS= 1E-6
%
% Function to apply the criteria (LIFT, DRAG, NEARFIELD_PRESS, SENS_GEOMETRY,
% SENS_MACH, DELTA_LIFT, DELTA_DRAG)
CAUCHY_FUNC_FLOW= DRAG
%
% Adjoint function to apply the convergence criteria (SENS_GEOMETRY, SENS_MACH)
CAUCHY_FUNC_ADJFLOW= SENS_GEOMETRY
%
% Epsilon for full multigrid method evaluation
%FULLMG_CAUCHY_EPS= 1E-4

% ------------------------- INPUT/OUTPUT INFORMATION --------------------------%
%
% Mesh input file
MESH_FILENAME= NACA0012_FFD.su2
%
% Mesh input file format (SU2, CGNS, NETCDF_ASCII)
MESH_FORMAT= SU2
%
% Divide rectangles into triangles (NO, YES)
DIVIDE_ELEMENTS= NO
%
% Convert a CGNS mesh to SU2 format (YES, NO)
CGNS_TO_SU2= NO
%
% Mesh output file
MESH_OUT_FILENAME= mesh_out.su2
%
% Restart flow input file
SOLUTION_FLOW_FILENAME= restart_flowALE.dat
%
% Restart linear flow input file
SOLUTION_LIN_FILENAME= solution_lin.dat
%
% Restart adjoint input file
SOLUTION_ADJ_FILENAME= solution_adj.dat
%
% Output file format (PARAVIEW, TECPLOT, STL)
OUTPUT_FORMAT= TECPLOT
%
% Output file convergence history (w/o extension)
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 linear flow
RESTART_LIN_FILENAME= restart_lin.dat
%
% Output file flow (w/o extension) variables
VOLUME_FLOW_FILENAME= flow
%
% Output file adjoint (w/o extension) variables
VOLUME_ADJ_FILENAME= adjoint
%
% Output file linearized (w/o extension) variables
VOLUME_LIN_FILENAME= linearized
%
% 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
%
% Output file surface linear coefficient (w/o extension)
SURFACE_LIN_FILENAME= surface_linear
%
% Writing solution file frequency
WRT_SOL_FREQ= 1000
%
% Writing convergence history frequency
WRT_CON_FREQ= 1

% ------------------------ GRID DEFORMATION PARAMETERS ------------------------%
%
% Kind of deformation (FFD_SETTING, HICKS_HENNE, PARABOLIC, NACA_4DIGITS,
% DISPLACEMENT, ROTATION, FFD_CONTROL_POINT,
% FFD_DIHEDRAL_ANGLE, FFD_TWIST_ANGLE,
% FFD_ROTATION, FFD_CAMBER, FFD_THICKNESS, FFD_VOLUME
% SURFACE_FILE)
DV_KIND= FFD_CONTROL_POINT_2D
%
% Marker of the surface to which we are going apply the shape deformation
DV_MARKER= ( airfoil )
%
% Parameters of the shape deformation
% - HICKS_HENNE ( Lower Surface (0)/Upper Surface (1)/Only one Surface (2), x_Loc )
% - FFD_CONTROL_POINT_2D ( FFD_BoxTag, i_Ind, j_Ind, x_Disp, y_Disp )
% - NACA_4DIGITS ( 1st digit, 2nd digit, 3rd and 4th digit )
% - PARABOLIC ( Center, Thickness )
% - DISPLACEMENT ( x_Disp, y_Disp, z_Disp )
% - ROTATION ( x_Orig, y_Orig, z_Orig, x_End, y_End, z_End )
% - OBSTACLE ( Center, Bump size )
% - FFD_CONTROL_POINT ( Chunk ID, i_Ind, j_Ind, k_Ind, x_Disp, y_Disp, z_Disp )
% - FFD_DIHEDRAL_ANGLE ( Chunk ID, x_Orig, y_Orig, z_Orig, x_End, y_End, z_End )
% - FFD_TWIST_ANGLE ( Chunk ID, x_Orig, y_Orig, z_Orig, x_End, y_End, z_End )
% - FFD_ROTATION ( Chunk ID, x_Orig, y_Orig, z_Orig, x_End, y_End, z_End )
% - FFD_CAMBER ( Chunk ID, i_Ind, j_Ind )
% - FFD_THICKNESS ( Chunk ID, i_Ind, j_Ind )
% - FFD_VOLUME ( Chunk ID, i_Ind, j_Ind )
DV_PARAM= ( wing, 1, 0, 0, 1 )
%
% New value of the shape deformation
DV_VALUE= 0.0001
%
% Number of smoothing iterations for FEA mesh deformation
DEFORM_LINEAR_ITER= 500
%
% Number of nonlinear deformation iterations (surface deformation increments)
DEFORM_NONLINEAR_ITER= 1
%
% Print the residuals during mesh deformation to the console (YES, NO)
DEFORM_CONSOLE_OUTPUT= YES
%
% Factor to multiply smallest cell volume for deform tolerance (0.001 default)
DEFORM_TOL_FACTOR = 0.001
%
% Type of element stiffness imposed for FEA mesh deformation (INVERSE_VOLUME,
% WALL_DISTANCE, CONSTANT_STIFFNESS)
DEFORM_STIFFNESS_TYPE= INVERSE_VOLUME
%
% Visualize the deformation (NO, YES)
VISUALIZE_DEFORMATION= YES
%

% --------------------- OPTIMAL SHAPE DESIGN DEFINITION -----------------------%
% Available Objective functions
% DRAG, LIFT, SIDEFORCE, PRESSURE, FORCE_X, FORCE_Y,
% FORCE_Z, MOMENT_X, MOMENT_Y, MOMENT_Z, EFFICIENCY,
% EQUIVALENT_AREA, THRUST, TORQUE, FREESURFACE

% Optimization objective function with optional scaling factor
% ex= Objective * Scale
OPT_OBJECTIVE= LIFT * -0.0001

% Optimization constraint functions with scaling factors, separated by semicolons
% ex= (Objective = Value ) * Scale, use '>','<','='
OPT_CONSTRAINT= ( DRAG < 0.032 ) * 0.001

% List of design variables (Design variables are separated by semicolons)
% - HICKS_HENNE ( 1, Scale | Mark. List | Lower(0)/Upper(1) side, x_Loc )
% - NACA_4DIGITS ( 4, Scale | Mark. List | 1st digit, 2nd digit, 3rd and 4th digit )
% - DISPLACEMENT ( 5, Scale | Mark. List | x_Disp, y_Disp, z_Disp )
% - ROTATION ( 6, Scale | Mark. List | x_Axis, y_Axis, z_Axis, x_Turn, y_Turn, z_Turn )
% - FFD_CONTROL_POINT ( 7, Scale | Mark. List | Chunk, i_Ind, j_Ind, k_Ind, x_Mov, y_Mov, z_Mov )
% - FFD_DIHEDRAL_ANGLE ( 8, Scale | Mark. List | Chunk, x_Orig, y_Orig, z_Orig, x_End, y_End, z_End )
% - FFD_TWIST_ANGLE ( 9, Scale | Mark. List | Chunk, x_Orig, y_Orig, z_Orig, x_End, y_End, z_End )
% - FFD_ROTATION ( 10, Scale | Mark. List | Chunk, x_Orig, y_Orig, z_Orig, x_End, y_End, z_End )
% - FFD_CAMBER ( 11, Scale | Mark. List | Chunk, i_Ind, j_Ind )
% - FFD_THICKNESS ( 12, Scale | Mark. List | Chunk, i_Ind, j_Ind )
% - FFD_VOLUME ( 13, Scale | Mark. List | Chunk, i_Ind, j_Ind )
% FFD_CONTROL_POINT_2D ( 15, Scale | Mark. List | FFD_BoxTag, i_Ind, j_Ind, x_Mov, y_Mov )

DEFINITION_DV= ( 15, 1.0 | airfoil | wing, 1, 0, 0, 1 ); ( 15, 1.0 | airfoil | wing, 2, 0, 0, 1 ); ( 15, 1.0 | airfoil | wing, 3, 0, 0, 1 ); ( 15, 1.0 | airfoil | wing, 4, 0, 0, 1 ); ( 15, 1.0 | airfoil | wing, 5, 0, 0, 1 ); ( 15, 1.0 | airfoil | wing, 6, 0, 0, 1 ); ( 15, 1.0 | airfoil | wing, 7, 0, 0, 1 ); ( 15, 1.0 | airfoil | wing, 8, 0, 0, 1 ); ( 15, 1.0 | airfoil | wing, 9, 0, 0, 1 ); ( 15, 1.0 | airfoil | wing, 10, 0, 0, 1 ); ( 15, 1.0 | airfoil | wing, 11, 0, 0, 1 ); ( 15, 1.0 | airfoil | wing, 12, 0, 0, 1 ); ( 15, 1.0 | airfoil | wing, 13, 0, 0, 1 ); ( 15, 1.0 | airfoil | wing, 14, 0, 0, 1 ); ( 15, 1.0 | airfoil | wing, 15, 0, 0, 1 ); ( 15, 1.0 | airfoil | wing, 16, 0, 0, 1 ); ( 15, 1.0 | airfoil | wing, 17, 0, 0, 1 ); ( 15, 1.0 | airfoil | wing, 18, 0, 0, 1 ); ( 15, 1.0 | airfoil | wing, 19, 0, 0, 1 ); ( 15, 1.0 | airfoil | wing, 20, 0, 0, 1 ); ( 15, 1.0 | airfoil | wing, 21, 0, 0, 1 ); ( 15, 1.0 | airfoil | wing, 22, 0, 0, 1 ); ( 15, 1.0 | airfoil | wing, 23, 0, 0, 1 ); ( 15, 1.0 | airfoil | wing, 24, 0, 0, 1 ); ( 15, 1.0 | airfoil | wing, 25, 0, 0, 1 );( 15, 1.0 | airfoil | wing, 1, 1, 0, 1 ); ( 15, 1.0 | airfoil | wing, 2, 1, 0, 1 ); ( 15, 1.0 | airfoil | wing, 3, 1, 0, 1 ); ( 15, 1.0 | airfoil | wing, 4, 1, 0, 1 ); ( 15, 1.0 | airfoil | wing, 5, 1, 0, 1 ); ( 15, 1.0 | airfoil | wing, 6, 1, 0, 1 ); ( 15, 1.0 | airfoil | wing, 7, 1, 0, 1 ); ( 15, 1.0 | airfoil | wing, 8, 1, 0, 1 ); ( 15, 1.0 | airfoil | wing, 9, 1, 0, 1 ); ( 15, 1.0 | airfoil | wing, 10, 1, 0, 1 ); ( 15, 1.0 | airfoil | wing, 11, 1, 0, 1 ); ( 15, 1.0 | airfoil | wing, 12, 1, 0, 1 ); ( 15, 1.0 | airfoil | wing, 13, 1, 0, 1 ); ( 15, 1.0 | airfoil | wing, 14, 1, 0, 1 ); ( 15, 1.0 | airfoil | wing, 15, 1, 0, 1 ); ( 15, 1.0 | airfoil | wing, 16, 1, 0, 1 ); ( 15, 1.0 | airfoil | wing, 17, 1, 0, 1 ); ( 15, 1.0 | airfoil | wing, 18, 1, 0, 1 ); ( 15, 1.0 | airfoil | wing, 19, 1, 0, 1 ); ( 15, 1.0 | airfoil | wing, 20, 1, 0, 1 ); ( 15, 1.0 | airfoil | wing, 21, 1, 0, 1 ); ( 15, 1.0 | airfoil | wing, 22, 1, 0, 1 ); ( 15, 1.0 | airfoil | wing, 23, 1, 0, 1 ); ( 15, 1.0 | airfoil | wing, 24, 1, 0, 1 ); ( 15, 1.0 | airfoil | wing, 25, 1, 0, 1 )
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Old   June 8, 2015, 11:57
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hlk
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I'm not sure exactly what you mean about it not working, but I can offer a couple of tips:
1. Check that the initial point is feasible, aka that the drag does not violate the constraint. Optimization routines often act in undesired ways if the initial point violates a constraint.
2. Alter the balance between the weight of the constraint and the objective. These weights serve two purposes: on the objective, a smaller weight can prevent the optimization from taking too large of a step on the first iteration. Too small of a scale can correspondingly lead the optimizer to take only very small steps and converge slowly. The balance between weights on several objectives and/or constraints tells the optimizer which to prioritize. Right now, the optimizer is prioritizing the drag constraint over the lift objective.
3. The sign of the objective is controlled within the python tools, where objectives that are traditionally maximized have been multiplied by -1, so you do not need the negative sign on the scale.
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Old   June 8, 2015, 12:48
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With "not working" i mean that after two evaluation the deformation diverges, and when i visualize the deformation i only see a vertical line. I've multiplied by -1 the lift because i'm doing this test case for the automotive field and i've to create more downforce (or negative lift). I really appreciate your help, i'll try your suggestions.
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Old   June 8, 2015, 13:11
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hlk
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Quote:
Originally Posted by Luca B View Post
With "not working" i mean that after two evaluation the deformation diverges, and when i visualize the deformation i only see a vertical line. I've multiplied by -1 the lift because i'm doing this test case for the automotive field and i've to create more downforce (or negative lift). I really appreciate your help, i'll try your suggestions.
You may need to alter the python tools to minimize lift/maximize downforce (I think that it may take the absolute value of the scaling factor). Or flip your geometry so that "down" is in the other direction.
The divergence could be due to either to the constraint being violated (where the optimizer would try to fix it so that it satisfies the constraint but doesn't have any information on how to do that on the first iteration), or due to the scaling factor being too large.
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