1 // SPDX-FileCopyrightText: Copyright (c) 2017-2024, HONEE contributors. 2 // SPDX-License-Identifier: Apache-2.0 OR BSD-2-Clause 3 4 /// @file 5 /// Helper functions for computing stabilization terms of a newtonian simulation 6 #include <ceed.h> 7 8 #include "newtonian_state.h" 9 10 // ***************************************************************************** 11 // Helper function for computing the variation in primitive variables, given Tau_d 12 // ***************************************************************************** 13 CEED_QFUNCTION_HELPER void dYFromTau(CeedScalar Y[5], CeedScalar Tau_d[3], CeedScalar dY[5]) { 14 dY[0] = Tau_d[0] * Y[0]; 15 dY[1] = Tau_d[1] * Y[1]; 16 dY[2] = Tau_d[1] * Y[2]; 17 dY[3] = Tau_d[1] * Y[3]; 18 dY[4] = Tau_d[2] * Y[4]; 19 } 20 21 // ***************************************************************************** 22 // Helper functions for computing the stabilization terms 23 // ***************************************************************************** 24 CEED_QFUNCTION_HELPER void StabilizationMatrix(NewtonianIdealGasContext gas, State s, CeedScalar Tau_d[3], CeedScalar strong_residual[5], 25 CeedScalar stab[5][3]) { 26 CeedScalar dY[5]; 27 StateConservative dF[3]; 28 // Zero stab so all future terms can safely sum into it 29 for (CeedInt i = 0; i < 5; i++) { 30 for (CeedInt j = 0; j < 3; j++) stab[i][j] = 0; 31 } 32 dYFromTau(strong_residual, Tau_d, dY); 33 State ds = StateFromY_fwd(gas, s, dY); 34 FluxInviscid_fwd(gas, s, ds, dF); 35 for (CeedInt i = 0; i < 3; i++) { 36 CeedScalar dF_i[5]; 37 UnpackState_U(dF[i], dF_i); 38 for (CeedInt j = 0; j < 5; j++) stab[j][i] += dF_i[j]; 39 } 40 } 41 42 CEED_QFUNCTION_HELPER void Stabilization(NewtonianIdealGasContext gas, State s, CeedScalar Tau_d[3], State ds[3], CeedScalar U_dot[5], 43 const CeedScalar body_force[5], CeedScalar stab[5][3]) { 44 // -- Stabilization method: none (Galerkin), SU, or SUPG 45 CeedScalar strong_residual[5] = {0}; 46 switch (gas->stabilization) { 47 case STAB_NONE: 48 break; 49 case STAB_SU: 50 FluxInviscidStrong(gas, s, ds, strong_residual); 51 break; 52 case STAB_SUPG: 53 FluxInviscidStrong(gas, s, ds, strong_residual); 54 for (CeedInt j = 0; j < 5; j++) strong_residual[j] += U_dot[j] - body_force[j]; 55 break; 56 } 57 StabilizationMatrix(gas, s, Tau_d, strong_residual, stab); 58 } 59 60 // ***************************************************************************** 61 // Helper function for computing Tau elements (stabilization constant) 62 // Model from: 63 // PHASTA 64 // 65 // Tau[i] = itau=0 which is diagonal-Shakib (3 values still but not spatial) 66 // ***************************************************************************** 67 CEED_QFUNCTION_HELPER void Tau_diagPrim(NewtonianIdealGasContext gas, State s, const CeedScalar dXdx[3][3], const CeedScalar dt, 68 CeedScalar Tau_d[3]) { 69 // Context 70 const CeedScalar Ctau_t = gas->Ctau_t; 71 const CeedScalar Ctau_v = gas->Ctau_v; 72 const CeedScalar Ctau_C = gas->Ctau_C; 73 const CeedScalar Ctau_M = gas->Ctau_M; 74 const CeedScalar Ctau_E = gas->Ctau_E; 75 const CeedScalar cv = gas->cv; 76 const CeedScalar mu = gas->mu; 77 const CeedScalar rho = s.U.density; 78 79 CeedScalar tau; 80 CeedScalar dts; 81 CeedScalar fact; 82 83 CeedScalar gijd_mat[3][3] = {{0.}}, velocity_term; 84 MatMat3(dXdx, dXdx, CEED_TRANSPOSE, CEED_NOTRANSPOSE, gijd_mat); 85 86 dts = Ctau_t / dt; 87 88 { // u_i g_ij u_j 89 CeedScalar gij_uj[3] = {0.}; 90 MatVec3(gijd_mat, s.Y.velocity, CEED_NOTRANSPOSE, gij_uj); 91 velocity_term = Dot3(s.Y.velocity, gij_uj); 92 } 93 94 tau = Square(rho) * (4. * Square(dts) + velocity_term) + Ctau_v * Square(mu) * DotN((CeedScalar *)gijd_mat, (CeedScalar *)gijd_mat, 9); 95 96 fact = sqrt(tau); 97 98 Tau_d[0] = Ctau_C * fact / (rho * (gijd_mat[0][0] + gijd_mat[1][1] + gijd_mat[2][2])) * 0.125; 99 Tau_d[1] = Ctau_M / fact; 100 Tau_d[2] = Ctau_E / (fact * cv); 101 102 // consider putting back the way I initially had it 103 // Ctau_E * Tau_d[1] /cv to avoid a division if the compiler is smart enough to see that cv IS a constant that it could invert once for all elements 104 // but in that case energy tau is scaled by the product of Ctau_E * Ctau_M 105 // OR we could absorb cv into Ctau_E but this puts more burden on user to know how to change constants with a change of fluid or units. Same for 106 // Ctau_v * mu * mu IF AND ONLY IF we don't add viscosity law =f(T) 107 } 108