[Hgholami]

Dear Foamer,
in solid solver of fsiFoam

if (interface().valid())
{
interface()->correct(DEqn);
}

what does this statement do?

any reporting about solidSolver that explained detail of code?

if (interface().valid())
{
interface()->updateDisplacement(pointD_);
interface()->updateDisplacementGradient(gradD_, gradDf_);
}
else
{
volToPoint_.interpolate(D_, pointD_);
gradD_ = fvc::cellLimitedGrad(D_, pointD_, lsCellGrad(), 0);
gradDf_ = fvc::fGrad(D_, pointD_, interpFaceGrad());
}

what does this part?

[bigphil]

Hi,

These two pieces of code are related to a correction in the discretisation at bi-material interfaces i.e. at internal faces shared by two different materials. At bi-material interfaces, there is a discontinuity in the displacement gradient and this causes problems for the standard discretisation (in particular, the gradient calculation).

This modified discretisation is described in the following paper:
Tukovic, Ivankovic, Karac, 2012, Finite-volume stress analysis in multi-material linear elastic body, International Journal for Numerical Methods in Engineering, 10.1002/nme.4390.

The code itself for the "interface()" class can be found at:
extend-bazaar/FluidSolidInteraction/src/fluidSolidInteraction/solidSolvers/solidModels/materialInterfaces/materialInterface

The subsequent solids4foam code essentially uses the same procedure but a different implementation that aims to be more general i.e. independent of the chosen mechanical law.

Philip