Release of Overset Mesh in foam-extend

The first version of Overset Mesh for foam-extend-4.0 is now available.

To access the source code, please contact Hrvoje Jasak ( and Vuko Vukcevic (

We have a parallelised overset assembly algorithm using different fringe (donor/acceptor) variants:

  1. manual fringe – user specified cellSet for acceptors,
  2. faceCells fringe – acceptors are face cells of a given patch,
  3. overlap fringe – automatically calculates overlap between regions, which can be minimised using different run-time selectable Donor Suitability Functions: noSuitability, patchDistance, cellVolumes, faceArea…

Once the fringe layer has been calculated, the actual interpolation from donors to acceptors is carried out using run-time selectable oversetInterpolation schemes:  injection, averageValue, inverseDistance…

Overset interpolation is parallelised with the same tools as the GGI, yielding good parallel scaling.

The overset interpolation can be carried out implicitly or explicitly (run-time choice):

  1. Implicit overset: interpolation from donors to acceptors is performed in each linear system solver interpolation, yielding strong coupling between regions.
  2. Explicit overset: interpolation from donors to acceptors is performed only to set the values before the solution of equations, yielding weak coupling between regions and requiring additional outer iterations.

We also made implicit overset fully mass conservative by enforcing the fringe conservation constraint inside the pressure equation via Lagrangian multiplier. The explicit overset is by virtue region-wise mass conservative.

All basic solvers are available within the package: icoOversetFoam, icoDyMOversetFoam, simpleOversetFoam, pimpleDyMOversetFoam…