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August 3, 2011, 16:37 
Mesh motion with Translation & Rotation

#1 
Member
anonymous
Join Date: Jun 2011
Posts: 58
Rep Power: 7 
Hello Everyone
I'm currently trying to set up a simulation of a plate translating and rotating in a 2D plane. After reading many other posts I figure using a moving mesh approach is best. Setup: Large Square Domain Inside the large domain I defined a circular Subdomain (this is what I use to move the mesh) Within the Subdomain there is a rectangular blade The Square Domain is defined to have Regions of motion specified Mesh Deformation Boundary Definitions: Outside Boundary (4 sides of the square domain) has stationary mesh motion Subdomain has specified location mesh motion using equations X New Tran Y Com Z New (see below) Inner Interface boundary (subdomain side of interface) has a specified location mesh motion using same equations as the subdomain Outer Interface boundary (Square domain side of interface) has a specified location mesh motion using the following equations X Still = x  Total Mesh Displacement X Y New Tran Z New All other boundaries have unspecified mesh motion. Mesh Motion: Case 1: Rotation Only I started by rotating the subdomain without translation using this thread as a guideline to define the location: http://www.cfdonline.com/Forums/cfx...gdomains.html These are the rotation equations i have used X New Rot: ((xX0)Total Mesh Displacement X)*cos(alpha)+((yY0)Total Mesh Displacement Y)*sin(alpha)+X0 Y New Rot: ((xX0)Total Mesh Displacement X)*sin(alpha)+((yY0)Total Mesh Displacement Y)*cos(alpha)+Y0 Z New: z  Total Mesh Displacement Z This rotated my subdomain and blade very nicely. Case 2: Translation Only Next I translated the subdomain without rotation using these equations of mesh motion X New Tran: ((xX0) Total Mesh Displacement X)+ 5 [cm rad^1] * sin(1 [rad s^1] *pi*t) Y New Tran: ((yY0) Total Mesh Displacement Y)+ 5 [cm rad^1] * sin(1 [rad s^1] *pi*t) Z New (use same as rotation) This translated my subdomain and blade very nicely Case 3: Rotation + Y Translation Next I tried to combine rotation with Y translations using these equations X New Rot (use same as rotation) Y Com = Y New Rot + Y New Tran  y Z New (use same as rotation) This is where i run into issues. When i use these equations rather than translating/rotating my subdomain, it skews my circle into a oval and rotates and continues to skew the oval. I'm cirtan that its errors in my equations but i'm not sure what from. If i had to guess i'm using the x,y and z variables as well as the Total Mesh Displacement variables wrong as i'm not completely sure of what they represent. Are x, y and z just the specific x y and z coordinate of a specific node on the mesh to be moved? Is the Total Mesh Displacement the overall displacement of a specific node from its original point to its current point in the x, y or z direction? Any help or advice would be greatly appreciated. Thank You, DM 

January 6, 2014, 13:17 
mesh translation

#2 
Senior Member
ali
Join Date: Oct 2009
Posts: 219
Rep Power: 10 
Hello,
Were you able to define translational mesh displacement in CFX? All I can find is rotational motion. Thanks 

January 12, 2014, 07:21 

#3 
Super Moderator
Glenn Horrocks
Join Date: Mar 2009
Location: Sydney, Australia
Posts: 12,838
Rep Power: 100 
Translational motion is a beta feature which I suspect is not fully implemented. Talk to ANSYS support if you want to know the status of it.


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