# Buoyancy driven flow of an incompressible fluid in a closed volume

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 July 20, 2015, 04:49 Buoyancy driven flow of an incompressible fluid in a closed volume #1 Member   Nicole Andrew Join Date: Sep 2014 Location: Pretoria, South Africa Posts: 58 Rep Power: 11 Good day, I am trying to solve for the steady state buoyancy driven flow field of an incompressible fluid in a closed volume. The density variations are a bit high (5-10%) for me to use the Boussinesq approximation (I think?), and seeing as I want to add more regions later, I am using chtMultiRegionSimpleFoam. I have a fundamental problem, however, because my domain is fixed, so normally the pressure would be adjusted to conserve mass within the volume, however my fluid is incompressible (icoPolynomial equation of state: it's density is only a function of temperature and not pressure), therefore this cannot be done. Someone has suggested adding a small hole somewhere non-consequential in my domain to allow for inflow and outflow to conserve mass during the iterations to steady state, and hopefully at steady state there will be no net flow. Has anyone else has experience doing this? Has anyone tried this solution? In reality, the surface of the liquid will move depending on the temperature, I am not keen to try and implement a moving mesh for this simple problem though, so I am looking for a simpler solution - if possible!

March 12, 2019, 21:24
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Jianrui Zeng
Join Date: May 2018
Location: China
Posts: 157
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Quote:
 Originally Posted by Nicole Good day, however my fluid is incompressible (icoPolynomial equation of state: it's density is only a function of temperature and not pressure), therefore this cannot be done.
So if density is changed with temperature but it is not related to pressure, it is still a incompressible problem?

I think the defference between incompressible and compressible is density is constant or not. Thank you.

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