# Rotational peridocity in domain?

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September 13, 2019, 14:02
Rotational peridocity in domain?
#1
New Member

Join Date: Dec 2018
Posts: 9
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I am wondering the limits of what the domain can be in order to apply periodic boundary conditions for a rotational region. I have seen examples in technical articles where the domain (fan, shroud, etc.) are all perfectly revolved cylinders essentially. If I have a circular fan in a square shroud, though, can I still divide it into "sectors" and apply periodic BC's? I mean, the flow field is essentially repeated at each of the four "quadrants" (see attached picture) correct? I feel I should be able to divide the domain into 25%, but am not sure.

Or can one not apply rotational BC's in FloEFD, only translational?
Attached Images
 Periodicity.jpg (73.3 KB, 9 views)

Last edited by 310toumad; September 13, 2019 at 16:07.

 October 18, 2019, 14:04 #3 New Member   Adam Join Date: Dec 2018 Posts: 9 Rep Power: 4 Thank you, it makes sense. So to enable sector periodicity, I'm assuming the assembly in SolidWorks has to be manipulated prior to opening Flow Simulation correct? So you would basically be performing an extrude cut to eliminate the sections you do not want, leaving only a "wedge" shaped portion of it. But my next question is, if you are running an internal simulation then these "open" sections that are exposed on either side of the wedge need lids, but the periodicity is not a boundary condition that can be applied to the face of the lids right? It is defined under computational domain I believe. So how would you handle the BC's for each side of the "wedge", because it is not as simple as having an inlet/outlet that opens to atmosphere.

October 18, 2019, 14:15
#4
Senior Member

Boris Marovic
Join Date: Jul 2009
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No, you leave the model as it is as you only change the computational domain which tells what to calculate and how. The model can stay as a whole.

No, it is as simple as that. Only what is in contact with the computational domain is used for the inlet or outlet BC. You only need to consider that you use a portion of the mass or volume flow as this is the overall amount. The velocity doesn't care how big the surface area of the inlet or outlet is.

Regards,
Boris
Attached Images
 sector.jpg (82.1 KB, 7 views)