[Annier]

Hi,
In solidDisplacementFoam solver,at tractionDisplacementFvPatchVectorField.C, there is a following piece of code for updateCoeffs().

void tractionDisplacementFvPatchVectorField::updateCoeffs()
{
...
gradient() =
    (
        (traction_ - pressure_*n)/rho
      + twoMuLambda*fvPatchField<vector>::snGrad() - (n & sigmaD)
    )/twoMuLambda;
...
fixedGradientFvPatchVectorField::updateCoeffs();
}

Whereas, in stressedFoam solver, at tractionDisplacementFvPatchVectorField.C;the corresponding code is:

void tractionDisplacementFvPatchVectorField::updateCoeffs()
{
...
gradient() =
    (
        (traction_ - pressure_*n)/rho.value()
      - (n & (mu.value()*gradU.T() - (mu + lambda).value()*gradU))
      - n*tr(gradU)*lambda.value()
    )/(2.0*mu + lambda).value();

fixedGradientFvPatchVectorField::updateCoeffs();
}

1. What does the value() assign to mu in mu.value()?
2. Similarly, the meaning of gradU.T().
3. Do they convert a scalar to a matrix of given size?
4. Is there a layman way to understand the process of coefficients being updated?


Yours
Anil Kunwar