van_leer_split_2d Subroutine

private pure subroutine van_leer_split_2d(q, dir, gam, fp, fm)

van Leer splitting: Mach-split mass flux carrying transverse momentum. Pressure split: p± = p(M±1)²(2∓M)/4 (subsonic); supersonic branches are fully upwind (fp==F, fm==0 for M≥1; fp==0, fm==F for M≤-1). Uses in (normal) and it (transverse) momentum indices to handle both directions uniformly.

Arguments

Type IntentOptional Attributes Name
real(kind=wp), intent(in) :: q(neq2d)
integer, intent(in) :: dir
real(kind=wp), intent(in) :: gam
real(kind=wp), intent(out) :: fp(neq2d)
real(kind=wp), intent(out) :: fm(neq2d)