Learning Forum

[ehkh]

Hi,

 

I am trying to simulate a natural convection problem in a rectangular cavity, I need to set the boundary conditions at the side walls as periodic.

could you please advice me how Periodic boundary condition can be specified in fluent 19.1.

 

Thanks

Esra

 

[Rob]

You can either create an identical mesh on both surfaces and then assign those as periodics or use a nonconformal boundary approach. Have a look in the documentation in the boundary conditions section(s). 

[oe15d020]

Hi

I am not sure whether i should start a new discussion. Since I have doubts about setting up periodic boundary condition(bc), I am posting my doubt here itself. Please help.

My problem is flow around a square cylinder. Flow is a cross flow to the cylinder axis and the span wise length of cylinder is assumed periodic in nature. In short, we are simulating the cross flow over a slice of an infinitely long square cylinder. I need to give translation periodic boundary conditions to the span end surfaces.

1. I created mesh in ICEM CFD with good quality.

2.Mesh check ok in fluent. Used mesh>mz>make-periodic and gave auto translate as well as manual cordinates for translation periodic bc.

3. Sometimes it creates periodic bc. But after that when i do mesh check, it fails.

4. Sometimes, its not creating periodic bc. On checking mesh-verbosity(2), it says 'couldn't find matching with the shadow face;.

5. I have done this before for a circular cylinder and was able to make periodic very easily. Similar mesh resolution is adopted for square cylinder and i am facing these problems, Could it be due to the skewness issues, i am not sure.

6. By default, the axis is Z axis in the cell zone. It was the same for my previous circular cylinder case file and there were no issue. My flow direction is X axis and translation periodic direction is in Z direction.

7. I tried to define span ends as 'interface' and applying 'periodic bc' in the mesh interface. Whether this approach can bypass the 'mesh>mz>make-periodic' way of doing is a doubt. Since the 'make-periodic' worked well for circular cross sections, i am curious why it is not working for square cylinders.