Set corner to freeslip but it doesn't work

#1

Test with code from examples/showCases/cylinder2d and with following modification to the cylinderSetup function, the function just wants to simulation a uniform flow, top and bottom boundary are set to freeslip. but unfortunately, it seems that corners are still dirichlet velocity points , not freeslip boundary points, velocity at these four corners is always zero.

I test the code on palabos v2.3.0 and latest version, they all give me the wrong result. Maybe there is something important I ignore, if someone can give some suggestion, I will be very appreciated.

void cylinderSetup(
    MultiBlockLattice2D<T, DESCRIPTOR> &lattice, IncomprFlowParam<T> const &parameters,
    OnLatticeBoundaryCondition2D<T, DESCRIPTOR> &boundaryCondition)
{
    const plint nx = parameters.getNx();
    const plint ny = parameters.getNy();

    Box2D inlet(0, 0, 1, ny - 2);
    Box2D outlet(nx - 1, nx - 1, 1, ny - 2);
    Box2D bottomWall(0, nx - 1, 0, 0);
    Box2D topWall(0, nx - 1, ny - 1, ny - 1);
    boundaryCondition.setVelocityConditionOnBlockBoundaries(lattice, inlet);
    boundaryCondition.setVelocityConditionOnBlockBoundaries(lattice, outlet, boundary::neumann);
    boundaryCondition.setVelocityConditionOnBlockBoundaries(lattice, bottomWall, boundary::freeslip);
    boundaryCondition.setVelocityConditionOnBlockBoundaries(lattice, topWall, boundary::freeslip);

    setBoundaryVelocity(lattice, inlet, Array<T, 2>(0.01, 0.));
    initializeAtEquilibrium(
        lattice, lattice.getBoundingBox(), 1.0, Array<T, 2>(0.01, 0.));
    lattice.initialize();
}

Best regrads

#2

It’s solved!

When palabos try to set freeslip corner, it will call CopyTangentialVelocityFunctional2D, and in there

lattice.get(iX - normalX, iY - normalY).computeVelocity(u);
if (normalX != 0) {
    u[0] = T();
}
if (normalY != 0) {
    u[1] = T();
}
lattice.get(iX, iY).defineVelocity(u);

So if you set a corner to freeslip, palabos in fact will set the corner point to zero velocity. In the meantime,
I realize that defining a corner to be freeslip is not correct in physical and should be avoided.

:grinning: