# Rotating cylinder

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 January 27, 2010, 13:47 Rotating cylinder #1 New Member   Join Date: Jan 2010 Posts: 4 Rep Power: 8 Hi everyone, I just started to use OpenFOAM and am currently studying the "Flow around a cylinder" tutorial. Suppose I want to see the effect of having the cylinder rotate. This would easily be configured by setting the boundary to moving wall and specifying the angular velocity. Is this possible? I have read about mesh motion mechanisms, but they seem like overkill in this case, since the mesh is not moving, only the cylinder wall is. Any help appreciated. Thanks, Ole

 January 27, 2010, 16:44 #2 Member   Patricio Bohorquez Join Date: Mar 2009 Location: Jaén, Spain Posts: 94 Rep Power: 9 That is an interesting problem. Could you use GGI boundary condition on the "inside" cylinder and keep us posted? You could try something similar to mixerGgi that lives into OpenFOAM-1.5-dev/tutorials/icoDyMFoam. Thanks, Patricio.

 January 27, 2010, 17:19 Using GGI changes problem to an unsteady one #3 New Member   Join Date: Jan 2010 Posts: 4 Rep Power: 8 Using GGI changes (as far as I understand) the problem to an unsteady one. I am interested in the steady solution, just like in the tutorial for the cylinder flow, except the cylinder should rotate with a constant speed. This amounts to setting the tangential velocity of the cylinder boundary to some uniform value, and then solving the steady problem. I can set the velocity on the boundary uniformly to some constant vector in cartesian coordinates, but is it possible to set the tangential velocity to some constant?

January 28, 2010, 11:32
#4
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Andrea Pasquali
Join Date: Sep 2009
Location: Germany
Posts: 142
Rep Power: 9
You can try with this BC in U file

Quote:
 cilindro { type rotatingWallVelocity; origin (0 0 0); axis (0 0 1); omega 50; }
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Andrea Pasquali

 January 28, 2010, 12:54 #5 New Member   Join Date: Jan 2010 Posts: 4 Rep Power: 8 Works perfectly! Thank you.

 February 2, 2010, 10:54 rotatingWallVelocity or MRFsimpleFoam #6 Senior Member     maddalena Join Date: Mar 2009 Posts: 436 Rep Power: 14 Hello everybody, I am wondering if a simpleFoam with a rotatingWallVelocity BC simulation can replace a MRFsimpleFoam simulation. They both are steadyState but: simpleFoam + rotatingWallVelocity: update the velocity considering the rotation, thus modify ALL the velocity term in the NS equations; MRFsimpleFoam: add a source term to the NS equations (see here). Anyone has studied the influence on results of these approach? Thanks to those that will shed some light! mad