# Modelizing two infinite parallel planes

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 April 2, 2013, 09:39 Modelizing two infinite parallel planes #1 New Member   ryu Join Date: Apr 2013 Posts: 7 Rep Power: 12 I want to know if there is any trick to modelize infinite geometries in fluent like two infinite parallel planes in 2D?

 April 3, 2013, 11:08 #2 Senior Member   OJ Join Date: Apr 2012 Location: United Kindom Posts: 473 Rep Power: 18 You can do it with the use of symmetry and streamwise-periodic boundary conditions. OJ kiurigan likes this.

 April 4, 2013, 07:40 #3 New Member   ryu Join Date: Apr 2013 Posts: 7 Rep Power: 12 Thanks for reply. But I can't use symmetry because I have a pressure gradient (which ensures the flow) and I can't use the periodic boundary condition because the two planes are in different temperatures and the use of periodic boundary condition obligates that all wall boundaries must be at the same temperature!! (see documentation here: https://www.sharcnet.ca/Software/Flu...hxfer-restrict)

 April 4, 2013, 08:32 #4 Senior Member   OJ Join Date: Apr 2012 Location: United Kindom Posts: 473 Rep Power: 18 Be careful with the interpretation of the words 1) Streamwise periodic conditions do allow temperature and pressure drop in streamwise direction. You need to select a domain length in streamwise direction such that these drops are same for the next domain of same length. http://jullio.pe.kr/fluent6.1/help/html/ug/node337.htm 2) "Constant wall temperature" doesn't mean all walls should be at same temperature. It means on any particular wall, the temperature everywhere should be the same, i.e. uniform without any profiles. But the temperatures of the streamwise-periodic boundary conditions can vary: https://www.sharcnet.ca/Software/Flu...c-hxfer-theory 3) I mentioned symmetry, since in 2D case with FLUENT, the domain itself becomes a symmetry boundary conditions, in whole perspective, with the boundaries perpendicular to the flow being streamwise periodic. In CFX, you have to use a thick domain to simulate the same 2D case, where you would use the symmetry boundary conditions to the boundaries parallel to the flow and streamwise periodic boundary conditions to the boundaries that are perpendicular to the flow. OJ kiurigan likes this.

 April 4, 2013, 09:51 #5 New Member   ryu Join Date: Apr 2013 Posts: 7 Rep Power: 12 Thank you so much. It seems that I misunderstood this sentence "all walls must be at the same temperature (profiles are not allowed)"!!

 Tags geometries, infinite, parallel, planes