The problem of bed load transport rate based on FE3.2-famesh
 

Hi all,
when i calculated the bed load transport rate (qbi=q0*τ/τi - C*|q0|dη/dxi) component in the i direction by using OpenFOAM famesh, i found the result of dη/dxi in two sides in y direction (two sides patch: symmetryPlane) is wrong by simulating the scour of pileline under current and using five layer grids. The result show the value is zero in internal face ceters in y direction, however it is very big in two sides. Please help me if someone know how to slove it. Thank you.

The code::):):)
//########################### bed load transport rate ###########################//
hA=mesh.boundaryField()[patchID].faceCentres.z();
edgeScalarField absWLEdge = fac::interpolate(hA);
areaVectorField gha = fac::edgeIntegrate(absWLEdge.mesh().Le() * absWLEdge);
// or //areaVectorField gha = fac::grad(hA);

areaVectorField qbA = q0A*shearN - 1.5 * mag(q0A) * gha;

Best,

LXJ

Which are your bc's for velocity in the spanwise direction?

Hi Santiago,

Yes, you are right. The spanwise direction (i.e., x direction) is set as the velocity direction. Two sides are perpendicular to y direction, and parallel to x direction.

Best,

Liu

Ok,

Two questions:

1. Which Boundary conditions you set for velocity in the domain?
2. Do you start your simulation from a solution obtained by not moving the grid/potential?

Hi, Santiago

Thank you for you reply. First, in order to explain this answer, i show a picture for the detailed model setup (plese ignore my clumsy drawing, :)), the Boundary conditions for the velocity is set in the left side of model. Second, i attempted the simulation by not moving the mesh motion, the result of grad(hA).y() is acquired in such condition and it is showed again in the attachment.

Best,

Liu

I also attempted the simulation by not considering the current velocity, i.e., i set the velocity is about zero. This value will not induce the sediment transport. Thus, no bad results were showed. :):):)

I am so sorry to trouble you again. I give a error introdution several minutes ago. When i use the smaller current velocity, the bed surface gradient is also wrong, please see the attachment. The error also exist in the patch junction. Is this indicate the fac::grad() is wrong in patch junction?

I need emphasize the gha.x() and gha.z() keep same variation for the five layer mesh. Just gha.y() show the error. Thank you.
:):):)