# getNEq_diffusive Function

## public function getNEq_diffusive(layout, omega, Sxx) result(nEq)

Calculate the non-equilibrium part of pdf from strain rate tensor based on the diffusive scaling

According to \cite Junk:2005cr \n The non-equilibrium part of pdf $f_i^{neq}$ is set by \n where $\nu' = \frac{\kappa c_s^2}{\omega}$ is the viscosity, $\bm S = \frac{1}{2}S^{(1)}$ is the strain rate tensor and and $D$ is the number of dimension. \n Notice here that strain rate tensor above has to be a traceless tensor, i.e. $Tr(S) = 0$. In current implementation, the above equation is slightly modified so that the strain rate tensor is not required to be traceless anymore. In this way, $f_i^{neq}$ calculated by this routine can recover the input strain rate tensor no matter it is traceless or not.\n Specificly the $\Lambda$ in above equation is modified slightly, i.e. This routine has a unit test program utest/mus_fNeq_diffusive_test

### Arguments

TypeIntentOptionalAttributesName
type(mus_scheme_layout_type), intent(in) :: layout
real(kind=rk), intent(in) :: omega
real(kind=rk), intent(in) :: Sxx(3,3)

Strain rate tensor. It is a symmetric 3x3 matrix

## Variables

TypeVisibilityAttributesNameInitial
integer, private :: iVal
integer, private :: jVal
integer, private :: iDir
real(kind=rk), private :: strain(3,3)