# DarcyForchheimer

From OpenFOAMWiki

The Darcy Forchheimer model allows us to simply add a porosity zone into our fluid domain without any expense. In order to use the model, you have to put a fvOptions file into the constant folder including the following content (OpenFOAM-v6):

/*--------------------------------*- C++ -*----------------------------------*\ | ========= | | | \\ / F ield | OpenFOAM: The Open Source CFD Toolbox | | \\ / O peration | Version: dev | | \\ / A nd | Web: www.OpenFOAM.org | | \\/ M anipulation | | \*---------------------------------------------------------------------------*/ FoamFile { version 2.0; format ascii; class dictionary; location "constant"; object fvOptions; } // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * // porosity1 { type explicitPorositySource; explicitPorositySourceCoeffs { selectionMode cellZone; cellZone cat1; type DarcyForchheimer; f (0.63 1e6 1e6); d (80.25 1e6 1e6); coordinateSystem { type cartesian; origin (0 0 0); coordinateRotation { type axesRotation; e1 (1 0 0); e2 (0 1 0); } } } }

# 1 The Darcy-Forchheimer Equation

The Darcy Forchheimer acts in the momentum equation as a sink term . Considering the momentum equation, it follows:

Here, the Cauchy stress tensor is not split into its deviatoric and hydrostatic part (shear-rate and pressure). The main important term is the source term which is given as:

While the coefficients and have to be specified in the fvOptions file (see code above). The souce term represents a sink as the sign is negative.

## 1.1 Calculate the Coefficients

In Progress...