Mesh motion with Translation & Rotation
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.
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
Outside Boundary (4 sides of the square domain) has stationary mesh motion
Subdomain has specified location mesh motion using equations
X New Tran
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
All other boundaries have unspecified 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.cfd-online.com/Forums/cfx...g-domains.html
These are the rotation equations i have used
X New Rot: ((x-X0)-Total Mesh Displacement X)*cos(alpha)+((y-Y0)-Total Mesh Displacement Y)*sin(alpha)+X0
Y New Rot: -((x-X0)-Total Mesh Displacement X)*sin(alpha)+((y-Y0)-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: ((x-X0) -Total Mesh Displacement X)+ 5 [cm rad^-1] * sin(1 [rad s^-1] *pi*t)
Y New Tran: ((y-Y0) -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.
Were you able to define translational mesh displacement in CFX? All I can find is rotational motion.
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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