1 // Copyright (c) 2017-2022, Lawrence Livermore National Security, LLC and other CEED contributors. 2 // All Rights Reserved. See the top-level LICENSE and NOTICE files for details. 3 // 4 // SPDX-License-Identifier: BSD-2-Clause 5 // 6 // This file is part of CEED: http://github.com/ceed 7 8 /// @file 9 /// Helper functions for computing stabilization terms of a newtonian simulation 10 11 #ifndef stabilization_h 12 #define stabilization_h 13 14 #include <ceed.h> 15 16 #include "newtonian_state.h" 17 18 // ***************************************************************************** 19 // Helper function for computing the variation in primitive variables, given Tau_d 20 // ***************************************************************************** 21 CEED_QFUNCTION_HELPER void dYFromTau(CeedScalar Y[5], CeedScalar Tau_d[3], CeedScalar dY[5]) { 22 dY[0] = Tau_d[0] * Y[0]; 23 dY[1] = Tau_d[1] * Y[1]; 24 dY[2] = Tau_d[1] * Y[2]; 25 dY[3] = Tau_d[1] * Y[3]; 26 dY[4] = Tau_d[2] * Y[4]; 27 } 28 29 // ***************************************************************************** 30 // Helper functions for computing the stabilization terms 31 // ***************************************************************************** 32 CEED_QFUNCTION_HELPER void StabilizationMatrix(NewtonianIdealGasContext gas, State s, CeedScalar Tau_d[3], CeedScalar strong_residual[5], 33 CeedScalar stab[5][3]) { 34 CeedScalar dY[5]; 35 StateConservative dF[3]; 36 // Zero stab so all future terms can safely sum into it 37 for (CeedInt i = 0; i < 5; i++) { 38 for (CeedInt j = 0; j < 3; j++) stab[i][j] = 0; 39 } 40 dYFromTau(strong_residual, Tau_d, dY); 41 State ds = StateFromY_fwd(gas, s, dY); 42 FluxInviscid_fwd(gas, s, ds, dF); 43 for (CeedInt i = 0; i < 3; i++) { 44 CeedScalar dF_i[5]; 45 UnpackState_U(dF[i], dF_i); 46 for (CeedInt j = 0; j < 5; j++) stab[j][i] += dF_i[j]; 47 } 48 } 49 50 CEED_QFUNCTION_HELPER void Stabilization(NewtonianIdealGasContext gas, State s, CeedScalar Tau_d[3], State ds[3], CeedScalar U_dot[5], 51 const CeedScalar body_force[5], CeedScalar stab[5][3]) { 52 // -- Stabilization method: none (Galerkin), SU, or SUPG 53 CeedScalar strong_residual[5] = {0}; 54 switch (gas->stabilization) { 55 case STAB_NONE: 56 break; 57 case STAB_SU: 58 FluxInviscidStrong(gas, s, ds, strong_residual); 59 break; 60 case STAB_SUPG: 61 FluxInviscidStrong(gas, s, ds, strong_residual); 62 for (CeedInt j = 0; j < 5; j++) strong_residual[j] += U_dot[j] - body_force[j]; 63 break; 64 } 65 StabilizationMatrix(gas, s, Tau_d, strong_residual, stab); 66 } 67 68 // ***************************************************************************** 69 // Helper function for computing Tau elements (stabilization constant) 70 // Model from: 71 // PHASTA 72 // 73 // Tau[i] = itau=0 which is diagonal-Shakib (3 values still but not spatial) 74 // ***************************************************************************** 75 CEED_QFUNCTION_HELPER void Tau_diagPrim(NewtonianIdealGasContext gas, State s, const CeedScalar dXdx[3][3], const CeedScalar dt, 76 CeedScalar Tau_d[3]) { 77 // Context 78 const CeedScalar Ctau_t = gas->Ctau_t; 79 const CeedScalar Ctau_v = gas->Ctau_v; 80 const CeedScalar Ctau_C = gas->Ctau_C; 81 const CeedScalar Ctau_M = gas->Ctau_M; 82 const CeedScalar Ctau_E = gas->Ctau_E; 83 const CeedScalar cv = gas->cv; 84 const CeedScalar mu = gas->mu; 85 const CeedScalar rho = s.U.density; 86 87 CeedScalar tau; 88 CeedScalar dts; 89 CeedScalar fact; 90 91 CeedScalar gijd_mat[3][3] = {{0.}}, velocity_term; 92 MatMat3(dXdx, dXdx, CEED_TRANSPOSE, CEED_NOTRANSPOSE, gijd_mat); 93 94 dts = Ctau_t / dt; 95 96 { // u_i g_ij u_j 97 CeedScalar gij_uj[3] = {0.}; 98 MatVec3(gijd_mat, s.Y.velocity, CEED_NOTRANSPOSE, gij_uj); 99 velocity_term = Dot3(s.Y.velocity, gij_uj); 100 } 101 102 tau = Square(rho) * (4. * Square(dts) + velocity_term) + Ctau_v * Square(mu) * DotN((CeedScalar *)gijd_mat, (CeedScalar *)gijd_mat, 9); 103 104 fact = sqrt(tau); 105 106 Tau_d[0] = Ctau_C * fact / (rho * (gijd_mat[0][0] + gijd_mat[1][1] + gijd_mat[2][2])) * 0.125; 107 Tau_d[1] = Ctau_M / fact; 108 Tau_d[2] = Ctau_E / (fact * cv); 109 110 // consider putting back the way I initially had it 111 // 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 112 // but in that case energy tau is scaled by the product of Ctau_E * Ctau_M 113 // 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 114 // Ctau_v * mu * mu IF AND ONLY IF we don't add viscosity law =f(T) 115 } 116 117 // ***************************************************************************** 118 119 #endif // stabilization_h 120