# OpenFOAM

Whatever worth sharing from my OpenFOAM journey

## SIMPLE scheme (2/3): Openfoam implementation-SimpleFoam

A walk through SimpleFoam wiki page . This is my study note of simpleFoam wiki page with links that helped me understand. Before simple loop createFields.H The included file createFields.H creates volumeScalarField p and volVectorField U from the 0 directory. Then it includes createPhi.H which creates surfaceScalarField phi with value fvc::flux(U) : It calls the …

## gaussLaplacianScheme(3/3): Adding source terms – fvOptions

Here, we continue the modification of the solver myThermalConductionSolver using fvOptions. Please see the previous post Effect of adding source su =1, sp = 0 case If we keep su=1 in constant/tansportProperties, the source is modified from 9(-150 -80 -80 -70 0 0 -130 -60 -60) to 9(-150.01 -80.01 -80.01 -70.01 -0.01 -0.01 -130.01 -60.01 …

## gaussLaplacianScheme(1/3): Theory and implementation in OpenFOAM

How the discretisation of the laplacian term is done? explicit evaluations, orthogonal corrections … Notes made while reading through report by Jesper Roland. This report has detailed explanation on laplacianScheme abstract class, various macros like TypeName, New,… etc. Options for laplacian scheme A typical system/fvSchemes will read like below: Gauss is the only laplacian scheme …

## Source term linearisation and Under-relaxation

as I learned from the awesome book If properly handled, source term improves solution stability. Consider a discretised conservation equation for a general variable with source in element C written below: If the RHS is large compared to the rest of the terms, the rate of convergence will be affected. In such cases, the rate …

## gaussLaplacianScheme(2/3): A test case in OpenFOAM

as I learned from the awesome book and from several posts in cfdonline This article is an outcome of an effort to learn programming in OpenFOAM. A basic conduction solver is made for the learning purpose. It is decided to document the same for the future reference. Understanding the fvMatrix (“A” matrix of Ax = …

## SIMPLE scheme (1/3): Theory

as I learned from the awesome book Derivation of SIMPLE scheme for 1D uniform grid A steady momentum equation may be wrote as follows. If it is one dimensional, the momentum and continuity equations are as follows (2) and (3): Representing pressure and velocity on the cell centre may lead to so called checker board …

## High Resolution schemes

HR scheme = Higher Order Scheme + a Convection Boundedness Criterion HR scheme can be obtained by either of the following method Smoothening an unbounded Higher Order scheme with diffusive flux. Enhancing a first order upwind scheme with a limited anti-diffusive flux (TVD schemes). Two frameworks used for convection boundedness are Normalized Variable Formulation (NVF) …