Fused van Leer flux splitting: returns F^+ and F^- in one call.
Extracts primitives once and evaluates both split fluxes, handling all Mach-number regimes (supersonic positive, subsonic, supersonic negative).
NOTE (energy flux): the mass and momentum splits are the classic van Leer (1982) polynomials, but the energy flux uses F^±_E = ṁ^± · H (mass flux × total enthalpy) — the Hänel, Schwane & Seider (1987) modification — rather than van Leer's original closed-form energy term ṁ^± ((γ-1)u ± 2c)² / (2(γ²-1)). A reader validating against van Leer (1982) will not find this energy closure there; see Hänel et al. (1987).
| Type | Intent | Optional | Attributes | Name | ||
|---|---|---|---|---|---|---|
| real(kind=wp), | intent(in) | :: | q(:) | |||
| real(kind=wp), | intent(out) | :: | fp(:) | |||
| real(kind=wp), | intent(out) | :: | fm(:) | |||
| real(kind=wp), | intent(in) | :: | gam |
Ratio of specific heats. |