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abelee February 20, 2012 22:52

a few questions on filteredLinear2
 
Hello Foamers:

I'm trying to use the interpolation scheme filteredLinear2. If I want to use filteredLinear2 on the divergence term then I believe the usage should look like:

divSchemes
{
div(phi,U) Gauss filteredLinear2 1 0;
}


It requires two coefficients (above the first coefficient is one and the second one is zero) and I think it is important that I assign appropriate values for the two coefficients. However, I'm not quite sure what values to choose when I want to run a LES case to study the flow over a cylinder at high Re.

I've looked into the source code and included some portion of the code description.

// Scaling corefficient for the gradient ratio,
// 0 = linear
// 1 = fully limited
scalar k_;

// Maximum allowed overshoot/undershoot relative to the difference
// across the face.
// On input:
// 0 = no overshoot/undershoot
// 1 = overshoot/undershoot equal to the difference across the face
// Note: After input 1 is added to l_


It seems like the first coefficient has something to do with limiter that is

0 = no limiter so it's just linear
1 = fully limited meaning it becomes like limitedLinear

Am I understanding it correctly? Please, correct me if I'm not.

Also about the second coefficient it says it has something to do with overshoot/undershoot, which I'm not quite sure what it is about.

Could anyone explain to me the details of the algorithm in filteredLinear2 and recommend appropriate values for the two coefficients?

A.Lee


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