1 // Copyright (c) 2017-2024, 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 #include <ceed.h> 11 12 #include "newtonian_state.h" 13 14 // ***************************************************************************** 15 // Helper function for computing the variation in primitive variables, given Tau_d 16 // ***************************************************************************** 17 CEED_QFUNCTION_HELPER void dYFromTau(CeedScalar Y[5], CeedScalar Tau_d[3], CeedScalar dY[5]) { 18 dY[0] = Tau_d[0] * Y[0]; 19 dY[1] = Tau_d[1] * Y[1]; 20 dY[2] = Tau_d[1] * Y[2]; 21 dY[3] = Tau_d[1] * Y[3]; 22 dY[4] = Tau_d[2] * Y[4]; 23 } 24 25 // ***************************************************************************** 26 // Helper functions for computing the stabilization terms 27 // ***************************************************************************** 28 CEED_QFUNCTION_HELPER void StabilizationMatrix(NewtonianIdealGasContext gas, State s, CeedScalar Tau_d[3], CeedScalar strong_residual[5], 29 CeedScalar stab[5][3]) { 30 CeedScalar dY[5]; 31 StateConservative dF[3]; 32 // Zero stab so all future terms can safely sum into it 33 for (CeedInt i = 0; i < 5; i++) { 34 for (CeedInt j = 0; j < 3; j++) stab[i][j] = 0; 35 } 36 dYFromTau(strong_residual, Tau_d, dY); 37 State ds = StateFromY_fwd(gas, s, dY); 38 FluxInviscid_fwd(gas, s, ds, dF); 39 for (CeedInt i = 0; i < 3; i++) { 40 CeedScalar dF_i[5]; 41 UnpackState_U(dF[i], dF_i); 42 for (CeedInt j = 0; j < 5; j++) stab[j][i] += dF_i[j]; 43 } 44 } 45 46 CEED_QFUNCTION_HELPER void Stabilization(NewtonianIdealGasContext gas, State s, CeedScalar Tau_d[3], State ds[3], CeedScalar U_dot[5], 47 const CeedScalar body_force[5], CeedScalar stab[5][3]) { 48 // -- Stabilization method: none (Galerkin), SU, or SUPG 49 CeedScalar strong_residual[5] = {0}; 50 switch (gas->stabilization) { 51 case STAB_NONE: 52 break; 53 case STAB_SU: 54 FluxInviscidStrong(gas, s, ds, strong_residual); 55 break; 56 case STAB_SUPG: 57 FluxInviscidStrong(gas, s, ds, strong_residual); 58 for (CeedInt j = 0; j < 5; j++) strong_residual[j] += U_dot[j] - body_force[j]; 59 break; 60 } 61 StabilizationMatrix(gas, s, Tau_d, strong_residual, stab); 62 } 63 64 // ***************************************************************************** 65 // Helper function for computing Tau elements (stabilization constant) 66 // Model from: 67 // PHASTA 68 // 69 // Tau[i] = itau=0 which is diagonal-Shakib (3 values still but not spatial) 70 // ***************************************************************************** 71 CEED_QFUNCTION_HELPER void Tau_diagPrim(NewtonianIdealGasContext gas, State s, const CeedScalar dXdx[3][3], const CeedScalar dt, 72 CeedScalar Tau_d[3]) { 73 // Context 74 const CeedScalar Ctau_t = gas->Ctau_t; 75 const CeedScalar Ctau_v = gas->Ctau_v; 76 const CeedScalar Ctau_C = gas->Ctau_C; 77 const CeedScalar Ctau_M = gas->Ctau_M; 78 const CeedScalar Ctau_E = gas->Ctau_E; 79 const CeedScalar cv = gas->cv; 80 const CeedScalar mu = gas->mu; 81 const CeedScalar rho = s.U.density; 82 83 CeedScalar tau; 84 CeedScalar dts; 85 CeedScalar fact; 86 87 CeedScalar gijd_mat[3][3] = {{0.}}, velocity_term; 88 MatMat3(dXdx, dXdx, CEED_TRANSPOSE, CEED_NOTRANSPOSE, gijd_mat); 89 90 dts = Ctau_t / dt; 91 92 { // u_i g_ij u_j 93 CeedScalar gij_uj[3] = {0.}; 94 MatVec3(gijd_mat, s.Y.velocity, CEED_NOTRANSPOSE, gij_uj); 95 velocity_term = Dot3(s.Y.velocity, gij_uj); 96 } 97 98 tau = Square(rho) * (4. * Square(dts) + velocity_term) + Ctau_v * Square(mu) * DotN((CeedScalar *)gijd_mat, (CeedScalar *)gijd_mat, 9); 99 100 fact = sqrt(tau); 101 102 Tau_d[0] = Ctau_C * fact / (rho * (gijd_mat[0][0] + gijd_mat[1][1] + gijd_mat[2][2])) * 0.125; 103 Tau_d[1] = Ctau_M / fact; 104 Tau_d[2] = Ctau_E / (fact * cv); 105 106 // consider putting back the way I initially had it 107 // 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 108 // but in that case energy tau is scaled by the product of Ctau_E * Ctau_M 109 // 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 110 // Ctau_v * mu * mu IF AND ONLY IF we don't add viscosity law =f(T) 111 } 112