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 R[5], CeedScalar stab[5][3]) { 33 CeedScalar dY[5]; 34 StateConservative dF[3]; 35 // Zero stab so all future terms can safely sum into it 36 for (CeedInt i = 0; i < 5; i++) { 37 for (CeedInt j = 0; j < 3; j++) stab[i][j] = 0; 38 } 39 dYFromTau(R, Tau_d, dY); 40 State ds = StateFromY_fwd(gas, s, dY); 41 FluxInviscid_fwd(gas, s, ds, dF); 42 for (CeedInt i = 0; i < 3; i++) { 43 CeedScalar dF_i[5]; 44 UnpackState_U(dF[i], dF_i); 45 for (CeedInt j = 0; j < 5; j++) stab[j][i] += dF_i[j]; 46 } 47 } 48 49 CEED_QFUNCTION_HELPER void Stabilization(NewtonianIdealGasContext gas, State s, CeedScalar Tau_d[3], State ds[3], CeedScalar U_dot[5], 50 const CeedScalar body_force[5], CeedScalar stab[5][3]) { 51 // -- Stabilization method: none (Galerkin), SU, or SUPG 52 CeedScalar R[5] = {0}; 53 switch (gas->stabilization) { 54 case STAB_NONE: 55 break; 56 case STAB_SU: 57 FluxInviscidStrong(gas, s, ds, R); 58 break; 59 case STAB_SUPG: 60 FluxInviscidStrong(gas, s, ds, R); 61 for (CeedInt j = 0; j < 5; j++) R[j] += U_dot[j] - body_force[j]; 62 break; 63 } 64 StabilizationMatrix(gas, s, Tau_d, R, stab); 65 } 66 67 // ***************************************************************************** 68 // Helper function for computing Tau elements (stabilization constant) 69 // Model from: 70 // PHASTA 71 // 72 // Tau[i] = itau=0 which is diagonal-Shakib (3 values still but not spatial) 73 // ***************************************************************************** 74 CEED_QFUNCTION_HELPER void Tau_diagPrim(NewtonianIdealGasContext gas, State s, const CeedScalar dXdx[3][3], const CeedScalar dt, 75 CeedScalar Tau_d[3]) { 76 // Context 77 const CeedScalar Ctau_t = gas->Ctau_t; 78 const CeedScalar Ctau_v = gas->Ctau_v; 79 const CeedScalar Ctau_C = gas->Ctau_C; 80 const CeedScalar Ctau_M = gas->Ctau_M; 81 const CeedScalar Ctau_E = gas->Ctau_E; 82 const CeedScalar cv = gas->cv; 83 const CeedScalar mu = gas->mu; 84 const CeedScalar u[3] = {s.Y.velocity[0], s.Y.velocity[1], s.Y.velocity[2]}; 85 const CeedScalar rho = s.U.density; 86 87 CeedScalar gijd[6]; 88 CeedScalar tau; 89 CeedScalar dts; 90 CeedScalar fact; 91 92 gijd[0] = dXdx[0][0] * dXdx[0][0] + dXdx[1][0] * dXdx[1][0] + dXdx[2][0] * dXdx[2][0]; 93 94 gijd[1] = dXdx[0][0] * dXdx[0][1] + dXdx[1][0] * dXdx[1][1] + dXdx[2][0] * dXdx[2][1]; 95 96 gijd[2] = dXdx[0][1] * dXdx[0][1] + dXdx[1][1] * dXdx[1][1] + dXdx[2][1] * dXdx[2][1]; 97 98 gijd[3] = dXdx[0][0] * dXdx[0][2] + dXdx[1][0] * dXdx[1][2] + dXdx[2][0] * dXdx[2][2]; 99 100 gijd[4] = dXdx[0][1] * dXdx[0][2] + dXdx[1][1] * dXdx[1][2] + dXdx[2][1] * dXdx[2][2]; 101 102 gijd[5] = dXdx[0][2] * dXdx[0][2] + dXdx[1][2] * dXdx[1][2] + dXdx[2][2] * dXdx[2][2]; 103 104 dts = Ctau_t / dt; 105 106 tau = rho * rho * 107 ((4. * dts * dts) + u[0] * (u[0] * gijd[0] + 2. * (u[1] * gijd[1] + u[2] * gijd[3])) + u[1] * (u[1] * gijd[2] + 2. * u[2] * gijd[4]) + 108 u[2] * u[2] * gijd[5]) + 109 Ctau_v * mu * mu * 110 (gijd[0] * gijd[0] + gijd[2] * gijd[2] + gijd[5] * gijd[5] + +2. * (gijd[1] * gijd[1] + gijd[3] * gijd[3] + gijd[4] * gijd[4])); 111 112 fact = sqrt(tau); 113 114 Tau_d[0] = Ctau_C * fact / (rho * (gijd[0] + gijd[2] + gijd[5])) * 0.125; 115 116 Tau_d[1] = Ctau_M / fact; 117 Tau_d[2] = Ctau_E / (fact * cv); 118 119 // consider putting back the way I initially had it 120 // 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 121 // but in that case energy tau is scaled by the product of Ctau_E * Ctau_M 122 // 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 123 // Ctau_v * mu * mu IF AND ONLY IF we don't add viscosity law =f(T) 124 } 125 126 // ***************************************************************************** 127 128 #endif // stabilization_h 129