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FFD shape deformation for 3D wing not changing the mesh 

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February 7, 2017, 09:40 
FFD shape deformation for 3D wing not changing the mesh

#1 
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Laurence
Join Date: Mar 2016
Posts: 2
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I'm trying to do standalone mesh deformation with SU2 (since I am using my own optimization routines) on the ONERAM6 3D mesh.
I am using the mesh_ONERAM6_turb.su2 mesh from the steady oneram6 optimization rans test case as a starting mesh. I am using the FFD box from the inviscid oneram6 example, which I implement with the following lines in my config file: %  FREEFORM DEFORMATION PARAMETERS % FFD_TOLERANCE= 1E10 % FFD_ITERATIONS= 500 % FFD_DEFINITION= (WING_BOX,0.0403, 0, 0.04836,0.8463,0, 0.04836,1.209,1.2896, 0.04836,0.6851,1.2896, 0.04836,0.0403,0, 0.04836,0.8463,0, 0.04836,1.209,1.2896, 0.04836,0.6851,1.2896, 0.04836) % FFD_DEGREE= (3, 2, 1) % FFD_CONTINUITY= 2ND_DERIVATIVE Running a mesh deformation with DV_KIND = FFD_SETTING works fine and produces the desired FFD control points. Now when I try to run the actual deformation, by adding the following lines in my config file: %  GRID DEFORMATION PARAMETERS % DV_KIND= FFD_CONTROL_POINT, FFD_CONTROL_POINT % DV_MARKER= ( wing ) % DV_PARAM= ( WING_BOX, 0, 0, 0, 0.0, 0.0, 1.0 ); ( WING_BOX, 0, 0, 1, 0.0, 0.0, 1.0 ) % DV_VALUE= 0.1, 0.1 % DEFINITION_DV= ( 7, 1.0  wing  WING_BOX, 0, 0, 0, 0.0, 0.0, 1.0 ); ( 7, 1.0  wing  WING_BOX, 0, 0, 1, 0.0, 0.0, 1.0 ) % VISUALIZE_DEFORMATION= YES The process seems to complete successfully, however when I look at the output mesh, and the ffd_boxes.dat output file shows no difference between the location of the control points. I believe I am following the steps outline in this thread FFD control point deformation, but it doesn't seem to be working. Any help would be much appreciated! The console output during the mesh deformation is given below:  Physical Case Definition  Input mesh file name: mesh_ONERAM6_turb_original.su2  Grid deformation parameters  Grid deformation using a linear elasticity method. Design variables definition (markers <> value <> param): FFD (control point) <> wing <> 0.001 <> ( WING_BOX, 0, 0, 0, 0, 0, 1 ) FFD (control point) <> wing <> 0.001 <> ( WING_BOX, 0, 0, 1, 0, 0, 1 )  Output Information  Output mesh file name: mesh_out.su2. A file will be created to visualize the deformation. Cell stiffness scaled by inverse of the cell volume.  Config File Boundary Information  Farfield boundary marker(s): farfield. Symmetry plane boundary marker(s): symmetry. Constant heat flux wall boundary marker(s): wing.  Read Grid File Information  Three dimensional problem. 96252 points before parallel partitioning. Performing linear partitioning of the grid nodes. 545438 interior elements before parallel partitioning. Calling the partitioning functions. Building the graph adjacency structure. Distributing elements across all ranks. 3 surface markers. 2802 boundary elements in index 0 (Marker = farfield). 16052 boundary elements in index 1 (Marker = symmetry). 2816 boundary elements in index 2 (Marker = wing). Calling ParMETIS... Finished partitioning using ParMETIS (24025 edge cuts). Communicating partition data and creating halo layers. 581834 interior elements including halo cells. 581834 tetrahedra. 109639 vertices including ghost points. Establishing MPI communication patterns.  Preprocessing computations  Setting local point connectivity. Checking the numerical grid orientation. Identify edges and vertices. Computing centers of gravity. Setting the bound control volume structure. Merging grid connectivity. Merging grid coordinates. Writing volume mesh file. Writing surface mesh file. Writing .su2 file.  Surface grid deformation  Performing the deformation of the surface grid. 1 Free Form Deformation boxes. 1 Free Form Deformation nested levels. FFD box tag: WING_BOX. FFD box level: 0. Degrees: 3, 2, 1. FFD Blending using Bezier Curves. Number of parent boxes: 0. Number of child boxes: 0. Corner points: 8. Control points: 24. Surface points: 1519. Writing a Paraview file of the FFD boxes.  FFD technique (parametric > cartesian)  Checking FFD box dimension. Checking FFD box intersections with the solid surfaces. The FFD planes j=0, intersect solid surfaces. SU2 is fixing the planes to maintain a continuous 2nd order derivative. Update cartesian coord  FFD box: WING_BOX. Max Diff: 1.53505e10. Writing a Paraview file of the FFD boxes.  Volumetric grid deformation  Performing the deformation of the volumetric grid. Computing volumes of the grid elements. Min. volume: 3.91157e13, max. volume: 1.41456. # LU_SGS preconditioner. # FGMRES residual history # Residual tolerance target = 3.91157e16 # Initial residual norm = 0.000362746 0 1 50 1.84268e09 100 9.02009e10 150 6.97651e10 200 1.7469e10 250 1.31106e10 300 4.44597e11 350 1.67551e11 400 6.43674e12 450 1.81654e12 500 3.95255e13 # FGMRES final (true) residual: # Iteration = 500: res/res0 = 3.95255e13. Computing volumes of the grid elements. Nonlinear iter.: 1/2. Linear iter.: 500. Min. volume: 3.91157e13. Error: 1.43377e16. Computing volumes of the grid elements. Min. volume: 3.91157e13, max. volume: 1.41456. # LU_SGS preconditioner. # FGMRES residual history # Residual tolerance target = 3.91157e16 # Initial residual norm = 0.000362746 0 1 50 1.84269e09 100 9.01976e10 150 6.97636e10 200 1.77482e10 250 1.33931e10 300 4.45252e11 350 1.66251e11 400 6.39568e12 450 1.82168e12 500 4.0082e13 # FGMRES final (true) residual: VISUALIZE_DEFORMATION= YES │# Iteration = 500: res/res0 = 4.0082e13. Computing volumes of the grid elements. Nonlinear iter.: 2/2. Linear iter.: 500. Min. volume: 3.91157e13. Error: 1.45396e16.  Write deformed grid files  Merging grid connectivity. Merging grid coordinates. Writing volume mesh file. Writing surface mesh file. Writing .su2 file. Adding any FFD information to the SU2 file. Completed in 77.826099 seconds on 8 cores. 19 │  Exit Success (SU2_DEF)  

February 13, 2017, 05:20 

#2 
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Tim Albring
Join Date: Sep 2015
Posts: 165
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Hi Laurence,
in the output is says: "The FFD planes j=0, intersect solid surfaces. SU2 is fixing the planes to maintain a continuous 2nd order derivative." Since both of your design variables are on the plane j=0, there will be no deformation. Tim 

February 15, 2017, 10:55 

#3 
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Laurence
Join Date: Mar 2016
Posts: 2
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Tim,
That makes sense, I've got it working fine now, thanks. 

July 25, 2017, 21:56 

#4 
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November 5, 2017, 05:01 

#5 
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JAMES
Join Date: Dec 2016
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August 1, 2019, 15:17 
FFD not interracting with geometry

#6 
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Angu Praveen
Join Date: May 2019
Posts: 12
Rep Power: 2 
Dear all,
I know this is a long shot. I am trying to optimize the wing section of a BWB aircraft. I am currently facing a problem where my FFD is not interacting with the geometry. I am not aware of how to get over this. So basically I ran the SU2_DEF and generated the FFD and then set up a few control points(198 in my case) as design variables and then run SU2_CFD and SU2_CFD_AD after that. Once all the calculations are done, I wanted to do the sensitivity analysis before going forward with the optimization. Unfortunately, my FFD intersects the geometry and all the gradients are "Zero". I tried changing the FFD_CONTINUITY to 'NO_DERIVATIVE', '1ST_DERIVATIVE' and also 2ND_DERIVATIVE. But the results are the same. It would be really helpful if you can help me bypass this issue, I've attached a few pictures and the outputs for your reference. Looking forward to hearing from you. Kind regards Angu  FFD technique (parametric > cartesian)  Checking FFD box dimension. Checking FFD box intersections with the solid surfaces. The FFD planes i=0, i=10, intersect solid surfaces. SU2 is fixing the planes to maintain a continuous 2nd order derivative. Update cartesian coord  FFD box: WING. Max Diff: 0. Design variable (FFD_CONTROL_POINT) number 0. DRAG gradient : 0  

Tags 
3d wing, ffd, mesh deformation, onera 
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