# OpenFOAM® v1712: New and improved numerics

31/12/2017

## [Re-]Integration of finite-area

The finite area library and many derivative applications have been integrated into this release from the foam-extend project. Porting to OpenFOAM v1712 was performed by Hrvoje Jasak in collaboration with OpenCFD Ltd.

The image below shows an example for the $FOAM_TUTORIALS/finiteArea/sphereSurfactantFoam/sphereTransport case visualised using the updated paraFoam ParaView reader module. Source code$FOAM_SRC/finiteArea
Solvers
$FOAM_SOLVERS/finiteArea/liquidFilmFoam$FOAM_SOLVERS/finiteArea/sphereSurfactantFoam
$FOAM_SOLVERS/finiteArea/surfactantFoam/planeTransport Examples$FOAM_TUTORIALS/finiteArea/liquidFilmFoam/cylinder
$FOAM_TUTORIALS/finiteArea/sphereSurfactantFoam/sphereTransport$FOAM_TUTORIALS/finiteArea/surfactantFoam/planeTransport
New avalanche modelling

This work was ported to OpenFOAM v1712 by Hrvoje Jasak - see commit commit 5dd072 and is based on the references:
• Tukovic, Z. The Finite Volume Method on Domains of Changeable Shape, PhD Thesis, University of Zagreb, Croatia, 2005
• Tukovic, Z., Jasak, H. A moving mesh finite volume interface tracking method for surface tension dominated interfacial fluid flow. Computers & fluids. 55 (2012) pp 70-84
Integration
Further integration has been performed by OpenCFD, e.g. paraFoam reader module and foamToVTK. For a complete list of changes, see merge #179

## New overset mesh functionality

The overset mesh capabilities introduced in OpenFOAM v1706 have been improved in many areas, including:

• parallel: improved momentum predictor performance, and re-visited tolerances for decompositions
• a new least-squares cell-cell stencil: gives higher accuracy at the potential cost of increased unboundeness

A comparison of the performance of the cell-cell stencil methods is shown below:

New overset aware solvers are now available:

• overPotentialFoam: potential flow; stationary mesh
• overRhoSimpleFoam: stationary mesh, steady compressible

The following image shows the potential solution for the Ahmed body using overPotentialFoam

and the subsequent viscous solution using the overRhoSimpleFoam solver:

Source code
$FOAM_SOLVERS/basic/potentialFoam/overPotentialFoam$FOAM_SOLVERS/compressible/rhoSimpleFoam/overRhoSimpleFoam
Examples
$FOAM_TUTORIALS/basic/overPotentialFoam/cylinder ## Updated particle tracking algorithm This release includes an update to the Lagrangian particle tracking from openfoam.org that locates the particles using barycentric co-ordinates. This introduces a change in file format where the positions file employed in earlier releases is replaced by a coordinates file. Additional integration efforts enable: • cases run in earlier versions to be updated automatically to the new format, and • provide the option to generate the positions file based on the entry writeLagrangianPositions in the$WM_PROJECT_DIR/etc/controlDict :

InfoSwitches
{
...
// Write lagrangian "positions" file in v1706 format (at earlier)
// if set to 1
writeLagrangianPositions 0;
...

This work was integrated from the openfoam.org version - see commit b7d082
Integration

## Deferred-correction scheme

The new deferredCorrection divergence scheme recovers the characteristics of a base scheme by separating the contributions between an implicit upwind contribution and an explicit correction. The base scheme is run-time selectable, e.g. to apply deferred-correction to the linear scheme:

divSchemes
{
div(phi,U)      Gauss deferredCorrection linear;
}

Source code
\$FOAM_SRC/finiteVolume/interpolation/surfaceInterpolation/schemes/deferredCorrection