Characteristic (Riemann-invariant) far-field ghost state for an OUTWARD unit normal nrm. q_int is the boundary-adjacent interior conserved state, q_inf the free-stream. With interior/free-stream normal velocities Un_i, Un_inf and sound speeds c_i, c_inf: * supersonic in/out (|Un_i| >= c_i) short-circuit to pure free-stream / pure interior extrapolation; * otherwise combine the outgoing (interior) invariant R+ = Un_i + 2 c_i/(gam-1) with the incoming (free-stream) R- = Un_inf - 2 c_inf/(gam-1) to get Un_b = (R+ + R-)/2, c_b = (gam-1)/4 (R+ - R-). Entropy and tangential velocity are taken from the free-stream on inflow (Un_b <= 0) and from the interior on outflow; rho_b, p_b follow from entropy + c_b. gam is passed explicitly (no module-level thermodynamic state here).
| Type | Intent | Optional | Attributes | Name | ||
|---|---|---|---|---|---|---|
| real(kind=wp), | intent(in) | :: | q_int(:) | |||
| real(kind=wp), | intent(in) | :: | q_inf(:) | |||
| real(kind=wp), | intent(in) | :: | nrm(2) | |||
| real(kind=wp), | intent(in) | :: | gam |