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Solar chimney- Natural convection, bouyancy driven flow

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Old   September 11, 2023, 14:15
Red face Solar chimney- Natural convection, bouyancy driven flow
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matteo Bartolini
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Hello everyone I'm a student trying to simulate the flow in a solar chimney and I'm new with Ansys fluent.

In order to study fluid dynamics problems at the inlet and outlet of the tower, it is located in an open domain.
I'm just interested in the fluid dynamics of the tower, for this reason, the geometry is composed by a rectangle of air from which I have subtracted the tower.

The mesh is a structured one and my boundary conditions are:

- Tower: no slip, adiabatic
- Collector: no slip, convection
- Absorber: no slip, fixed temperature
- Ground: no slip, adiabatic

The real problem are the boundary conditions at the sides of the rectangle.

For those boundary conditions i have tried different combinations:

-pressure inlet+pressure outlet
-velocity inlet+pressure outlet
-pressure inlet+pressure far field
-velocity inlet+pressure far field

but in every case I have problems with the pressure or velocity field.

in every simulation I'm using the pressure solver with k-eps model RNG, standard wall function, full buoyancy effect with this setup:

for the pressure velocity coupling scheme, I start with simple and finish with coupled performing 5000 iterations for every scheme
other settings
-pressure: body force weight
-momentum, turbulent kinetic, turbulent dissipation: first-order upwind

Default relaxation factors

Operating conditions are:
-operating pressure: 0 (setting gauge pressure equivalent to atmospheric pressure )
-gravity: y=-9.8 m/s2
-operating temperature: 308K

I think the problem is not well-posed and this is the reason because of pressure and velocity field problems.

I'd be very glad if someone could help me with some advice.

Regards Matteo
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boundaries condition, buoyancy driven flow, natural convection, pressure and velocity

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