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Viscosity and pressure - Newtonian

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Old   January 18, 2019, 05:32
Default Viscosity and pressure - Newtonian
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Zander Meiring
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Good day all,


I am using the simpleFoam solver with a Newtonian transport model, where only kinematic viscosity is needed (nu).
After solving, my main point of consideration is pressures, which is by default given as P/rho. I am working with air at 15C so


nu = 1.47e-5
mu = 1.802e-5
rho = 1.225


Would there be any negative consequence to changing the properties such that I set rho = 1, and therefore use a nu = 1.802e-5? This would mean that my pressures don't need to be multiplied by density, but I am unsure if this would cause differences in regards to the turbulence models when computing turbulent viscosity.
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Old   January 18, 2019, 07:16
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Henrik Johansson
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Hi Zander,

Density is not solved with simpleFoam. The effect of density is as you said pressure(in OpenFoam) = P/rho.
Thus your indata for pressure shall be P divided by density of your fluid. Changing density to 1 would be unphysical if you are trying to solve air at 15C.
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