[TSchenkel]

Cheers Adrian, that answered the second part of the question we hadn’t asked yet: would the off-axis work for pressure BC as well? Since the off-axis, off-lattice BCs seem to be for wall and velocity only. If I understand you correctly, the answer is “No”.

So our best approach would be to add an extension to the geometry and make it align with the lattice.

Since we only have the velocity waveform for the inlet, the swap to pressure inlet and velocity outlet (like in the bifurcation3d example) is not an option in this case.

With our geometry I think the geometry is such that an extension of the indicator cylinder would mean that the wall would not intersect with the extended cylinder (since the vessel opens up in places going inward from the outlet), as you suggested.

So we’ll have to add the extensions to the geometry to accommodate for these limitations in the LBM BC definition and lattice orientation.

Is there something like Bouzidi for pressure?

• This reply was modified 4 months, 2 weeks ago by TSchenkel.

[TSchenkel]

Thanks a lot for the confirmation. Is there a reason why it only reported the magnitude, rather than the vector?

[TSchenkel]

Thanks.

ad 1: That is what I figured. I checked that by setting up the STLReader and modified the functor to output the normals (will need those for other postprocessing). They did indeed all point towards the centre.

ad 2: How difficult would it be to set up such an analytical functor? Just starting to get my head round OpenLB (and object-oriented C++). Where would I start looking for something to use as a template for such a functor?

Re 3D WSS vector, does the following change to latticePhysWallShearStress3D.hh look correct to output the WSS vector in 3D in the global coordinate system?

l49:

SuperLatticePhysF3D<T, DESCRIPTOR>(sLattice, converter, 3), // changed this from 1 to 3 to give WSS vector

l155ff:

    T WSS[3];
    WSS[0] = traction[0] - tractionNormalComponent[0];
    WSS[1] = traction[1] - tractionNormalComponent[1];
    WSS[2] = traction[2] - tractionNormalComponent[2];
    // magnitude of the wall shear stress vector
    // output[0] = util::sqrt(WSS[0]*WSS[0] + WSS[1]*WSS[1] + WSS[2]*WSS[2]);
    //
    // Output all 3 components of WSS vector
    output[0]= WSS[0];
    output[1]= WSS[1];
    output[2]= WSS[2];

• This reply was modified 9 months ago by TSchenkel.
• This reply was modified 9 months ago by TSchenkel.

[Author]

Posts