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Katabatic flow using buoyantboussinesqpisofoam

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.

Thank you in advance
Tobias

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 ;)

Hi Nima Sam,

Thank you very much for your response. I'll check it out.

Cheers,
Tobias

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