2018-08-09 10:16:05 +02:00

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/*
This file implements the Central upwind flux
Copyright (C) 2016, 2017, 2018 SINTEF ICT
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
/**
* Central upwind flux function
*/
__device__ float3 CentralUpwindFlux(const float3 Qm, float3 Qp, const float g) {
const float3 Fp = F_func(Qp, g);
const float up = Qp.y / Qp.x; // hu / h
const float cp = sqrt(g*Qp.x); // sqrt(g*h)
const float3 Fm = F_func(Qm, g);
const float um = Qm.y / Qm.x; // hu / h
const float cm = sqrt(g*Qm.x); // sqrt(g*h)
const float am = min(min(um-cm, up-cp), 0.0f); // largest negative wave speed
const float ap = max(max(um+cm, up+cp), 0.0f); // largest positive wave speed
return ((ap*Fm - am*Fp) + ap*am*(Qp-Qm))/(ap-am);
}