OpenFoam Transient Wind Velocity Problems
 

Hello all, I'm quite new to OpenFoam, so in all likelihood this will be a stupid mistake on my part!

I am attempting to run a transient simulation (rhoreactingbuoyantfoam) of a gas leak, with parabolic wind conditions. I've tried mesh refinement and running with uniform wind velocity and the same thing also happens. As I increase the timestep, the velocity past the inlet increases exponentially, to supersonic speeds. This region lasts for about 20 meters, after which the velocity is flowing in the negative direction, or is close to zero.

I've attached the files for U, P and p_rgh.

Any help would be much appreciated!

Thanks,
Zach

From my experience, buoyancy and addition free stream does not work very well and gib unrealistic high velocity at points where the buoyancy ends (downstream).
I have decoupled the physics for my application. May be there is another was. I would be interested reading a solution.

Hello. What do you mean by «I have decoupled the physics » ? You don't add the buyoyancy term to the momentum NavierStokes Equation ?

That is not easy. But in principle, I solved the buoyancy alone and used the result as boundary conditions for a fress stream simulation.

You have to decide where the flow is buoyancy dominated. Of course you intrduce some error in the region where both, buoyancy and free stream, act. But you get a result at all.

It was a few years ago and I don't know every thing I tried. But at least a used a "mixing area" where I added the buoyancy effects (beyond the buoyancy limit) to the free stream simualtion.