Franjcf / hybridPorousInterFoam

OpenFOAM solver for performing single- and two-phase flow simulations on hybrid-scale porous media.
GNU General Public License v3.0
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Questions about viscous terms #8

Open tiandixuanhuang1 opened 1 year ago

tiandixuanhuang1 commented 1 year ago

Dear authors:

Hello and thank you for providing such an excellent open source toolkit! I learned a lot from this kit.

I have a question about the code in the toolkit (using OpenFoam version V8), and there is a piece of code in the UEqn.H file

fvVectorMatrix UEqn ( (1./eps)*(fvm::ddt(rho, U) + fvm::div(rhoPhiByEps, U) + MRF.DDt(rho, U))

This code is a finite volume discrete assembly of the macroscopic momentum equation multiplied by a system of linear algebraic equations, which I think is the corresponding equation (refer to the formula (21) in the paper “Multiphase flow modeling in multiscale porous media:An open-source micro-continuum approach”).

$\frac{1}{\phi}(\frac{\partial \rho\bar{\pmb{v}}}{\partial t} + \nabla\cdot(\frac{\rho}{\phi}\bar{\pmb{v}}\bar{\pmb{v}})) = -\nabla\bar{p} + \rho\pmb{g} + \nabla\cdot\bar{S} - \mu k^{-1}\bar{\pmb{v}} + \pmb{F}_c$

One of the things I am confused about is why the viscous term $\nabla\cdot\bar{S}$ is multiplied by 1/eps in the code (shown below), because the equation (21) does not multiply this coefficient, is there any key information I am missing? (1./eps)*(turbulence->divDevTau(rho, U))

I am looking forward to your reply and best wishes : )