Questions about pressure calculation on buoyancy flow(thermal stratified flow)
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Hey guys,
I am stuck on the problem to compute the pressure distribution of buoyancy flow, a large reservoir with temperature stratification. The CFX theory/modeling Guide says: "For buoyancy calculation, a source term is added to the momentum equations as follows: S_m,buoy = (rho - rho_ref)*g. When buoyancy model is activated, the pressure in the momentum equation excludes the hydrostatic gradient due to rho_ref. This pressure is related to the absolute pressure as follows: P_abs = P + P_ref + rho_ref*g(r - r_ref) where r_ref is a reference location." I learned that 'pressure' at the inlet boundary can be computed from equation like this 'integration dP =Integration (rho - rho_ref)*g dz' where z is the depth direction. See the picture as well. The model is simplified as shown in the figure. The tank has a vertical temperature stratification(i.e. temperature is a function with regard to depth), and the density is a function of temperature, and the pressure is relevant with the density but I am not sure how to calculate. So, my question is, how can I set the static pressure at the inlet boundary? Does it matter to the results? I computed the pressure using the method in the figure, and the simulation is not converged. I do not figure out the problem. Any suggestions? I will very appreciate your help. Thank you very much. |
If you are defining pressure then can't you use a single constant value over the entire inlet? As the documentation says that hydrostatic pressure component has been taken out of the pressure variable.
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Thank you so much. |
another question:
consider no thermal stratification, inlet pressure can be set to constant? I did that before. I want to confirm that. Thank you! |
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Yes, the inlet can be set to a constant with no thermal stratification as well. You should just try these options and find this all out for yourself. |
I see.
Thank you so much. |
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