# Rotating Frame Boundary Conditions

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 July 12, 2013, 11:06 Rotating Frame Boundary Conditions #1 New Member   Join Date: Jul 2013 Posts: 1 Rep Power: 0 I am simulating using ANSYS Workbench (14) a heated rotating tank setup which is two concentric thin cylinders with water in between and temperature boundary conditions at the bottom. The setup looks like a rectangle in the axisymmetric swirl situation. I've set the cell zone to have a rotating frame motion. The FLUENT tutorial guide suggests that the walls must be stationary for such a rotating tank whereas the help file explicitly states that it must be set as a moving wall (which implies a zero angular velocity relative to adjacent cell zone) Which one is correct? Also, for an open top, I've set it as a zero shear boundary. Is it appropriate? Please mention the corresponding initial conditions as well. Last edited by gpavanb; July 12, 2013 at 15:19. Reason: Clarity

 July 17, 2013, 03:15 #2 Senior Member     A-A Azarafza Join Date: Jan 2013 Posts: 187 Rep Power: 4 Hey dude According to my own experience in stirred tank, you don't need to exert a rotation to the walls if you are using absolute reference velocity. The only is required is that you must specify a rotating velocity to the fluid between the cylinders. __________________ Regard yours

 July 18, 2013, 08:19 #3 New Member   Join Date: Nov 2011 Posts: 17 Rep Power: 5 Dear gpavanb, By the open top you understand the free surface of liquid in the tank? If yes, and you do not want to simulate swirl creation etc. you should use symmetry BC. As for the walls. In my simulations of tank with Rushton turbine I use the following approach. I'm creating a separate zone which includes the turbine. The movement of the blades is forced by the MRF method whereas the rotation of the stirrer shaft is achieved by the moving wall settings. I hope that will help. Best regards

 July 19, 2013, 03:13 #4 Senior Member     A-A Azarafza Join Date: Jan 2013 Posts: 187 Rep Power: 4 @ Gimlas You right. But you could've encircled the stirrer shaft into your MRF zone too. The both is correct. __________________ Regard yours

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