# Katabatic flow using buoyantboussinesqpisofoam

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April 18, 2013, 10:30
Katabatic flow using buoyantboussinesqpisofoam
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Join Date: May 2011
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Hi all,

I am using a bouyantBoussinesq solver (LES) to model a katabatic wind flow along a slope. The surface temperature (wall) is slightly cooler than the overlying stably stratified atmosphere (see figure 1).

I like to use cyclic boundary conditions for the left and right patch, in order to get a fully developed turbulent wind field. Since the inlet and outlet are not at the same height, this causes a jump of the pressure field (see picture 2).

It is probably not possible to use a cyclic boundary condition here, or is there a way to solve this problem?

The other solution might be to rotate the frame of reference by aligning the x-axis with the slope, but I am not quite sure how to do this.

Tobias
Attached Images
 p.png (4.6 KB, 10 views)
Attached Files
 katabaticFlow.pdf (12.5 KB, 14 views)

 April 19, 2013, 03:43 #2 Senior Member   Nima Samkhaniani Join Date: Sep 2009 Location: Tehran, Iran Posts: 1,193 Blog Entries: 1 Rep Power: 16 you can use cyclic BC with pressure Jump, pressure Jump can be accessed by fan type BC at inlet-outlet, search in forum about fan BC __________________ Telegram channel (https://telegram.me/openfoam4Iranian) My Weblog (http://openfoam.blogfa.com/) Training Course on OpenFOAM at (http://www.isme.ir/)

 April 19, 2013, 04:05 #3 New Member   Join Date: May 2011 Posts: 6 Rep Power: 7 Hi Nima Sam, Thank you very much for your response. I'll check it out. Cheers, Tobias

 April 19, 2013, 09:09 #4 New Member   Join Date: May 2011 Posts: 6 Rep Power: 7 Hi Niam, I have applied the following boundary conditions to the left and right patch, respectively. But the result is still the same. Do I make something wrong? Code: ``` left { type fan; patchType cyclic; jump uniform 0; f 2(100 -1.0); value uniform 0; } right { type fan; patchType cyclic; jump uniform 0; f 2(100 -1.0); value uniform 0; }``` Thank you very much. Tobias

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