[letzel]

Dear Foamers,

my set-up is a cooling tower. The lowest some meters of the air within this tower act as a porous medium. This porous volume has a cylinder geometry.

Let's say the characteristic vertical coordinates (height above ground) are

• z1: bottom of tower, equal to bottom of porous region
• z2: top of porous region
• z3: top of tower

with 0 < z1 < z2 << z3.

The porous volume acts as a flow conditioner/straightener insofar as u=v=0 within this volume, only w /= 0, i.e. only vertical motion is possible.

Is it possible to realize the following strategy with OpenFOAM, and if so, how?

1. Combine the two solvers porousSimpleFoam and buoyantBoussinesqSimpleFoam into a new solver that includes porosity as well as buoyancy.
2. To drive the flow only by means of buoyancy, prescribe temperature at height z2.
3. To model the effect of the flow conditioner/straightener, force u=v=0 at z1 and z2.
4. My target is to measure the volume flow of air that leaves the tower at height z3, as well as pressure differences between the height levels z1, z2, z3.

Is it possible/advisable to create internal patches at z1, z2 and z3 to solve tasks 2, 3 and 4, and if so, how? Or are there different solutions?

Best regards,
Marcus