#include <ERF_WallGradientCoeffs.H>

Collaboration diagram for WallGradCoeffs:

Public Attributes
amrex::Real	c_wall

amrex::Real	c_0

amrex::Real	c_1

Detailed Description

Coefficients of the one-sided z-gradient of a cell-centered velocity at a Dirichlet (no-slip) z wall,

du/dz|wall = (c_wall * u_wall + c_0 * u_0 + c_1 * u_1) / dz0,

where u_wall is the wall value, u_0 and u_1 are the first and second cells off the wall, and dz0 and dz1 are their heights. This is the stencil ComputeStrain_S and ComputeStrain_T use for the wall stress, with the same arithmetic; on a uniform mesh it reduces to (-8/3, 3, -1/3), the stencil of ComputeStrain_N. It is second order, so it is exact for a quadratic profile. The coefficients sum to zero.

The implicit vertical momentum solve closes its wall row with this same gradient: the solve removes the explicit wall stress (from tau_corr) and puts back its own, so any other wall stencil changes the operator by implicit_fac * (L_solve - L_explicit) at the wall, and moves the steady state of a wall-bounded flow.

Member Data Documentation

◆ c_0

amrex::Real WallGradCoeffs::c_0

◆ c_1

amrex::Real WallGradCoeffs::c_1

Referenced by ImplicitDiffForMomLU_N(), ImplicitDiffForMomLU_S(), and ImplicitDiffForMomLU_T().

◆ c_wall

amrex::Real WallGradCoeffs::c_wall