In the Virtual Test Facility, fluid-structure coupling is based on an Eulerian-Lagrangian approach in which the solid slides through the fixed Cartesian fluid mesh. The data communication between the solvers is accomplished through the Eulerian-Lagrangian Coupling package. The transformation of the triangular solid surface meshes into distance functions on the Cartesian mesh is done with the Closest Point Transform package.
Both packages are built on top of the Algorithms and Data Structures package and the Computational Geometry package.
As part of the Numerical Algorithms package, Inter-/Extrapolation routines are provided to calculate values on Cartesian meshes covered by level-sets.