def BSSN_source_terms_for_BSSN_RHSs(custom_T4UU=None): global sourceterm_trK_rhs, sourceterm_a_rhsDD, sourceterm_lambda_rhsU, sourceterm_Lambdabar_rhsU # Step 3.a: Call BSSN_source_terms_ito_T4UU to get SDD, SD, S, & rho if custom_T4UU == "unrescaled BSSN source terms already given": SDD = ixp.declarerank2("SDD", "sym01") SD = ixp.declarerank1("SD") S = sp.symbols("S", real=True) rho = sp.symbols("rho", real=True) else: SDD, SD, S, rho = stress_energy_source_terms_ito_T4UU_and_ADM_or_BSSN_metricvars( "BSSN", custom_T4UU) PI = par.Cparameters("REAL", thismodule, ["PI"], "3.14159265358979323846264338327950288") alpha = sp.symbols("alpha", real=True) # Step 3.b: trK_rhs sourceterm_trK_rhs = 4 * PI * alpha * (rho + S) # Step 3.c: Abar_rhsDD: # Step 3.c.i: Compute trace-free part of S_{ij}: import BSSN.BSSN_quantities as Bq Bq.BSSN_basic_tensors() # Sets gammabarDD gammabarUU, dummydet = ixp.symm_matrix_inverter3x3( Bq.gammabarDD) # Set gammabarUU tracefree_SDD = ixp.zerorank2() for i in range(3): for j in range(3): tracefree_SDD[i][j] = SDD[i][j] for i in range(3): for j in range(3): for k in range(3): for m in range(3): tracefree_SDD[i][j] += -sp.Rational(1, 3) * Bq.gammabarDD[ i][j] * gammabarUU[k][m] * SDD[k][m] # Step 3.c.ii: Define exp_m4phi = e^{-4 phi} Bq.phi_and_derivs() # Step 3.c.iii: Evaluate stress-energy part of AbarDD's RHS sourceterm_a_rhsDD = ixp.zerorank2() for i in range(3): for j in range(3): Abar_rhsDDij = -8 * PI * alpha * Bq.exp_m4phi * tracefree_SDD[i][j] sourceterm_a_rhsDD[i][j] = Abar_rhsDDij / rfm.ReDD[i][j] # Step 3.d: Stress-energy part of Lambdabar_rhsU = stressenergy_Lambdabar_rhsU sourceterm_Lambdabar_rhsU = ixp.zerorank1() for i in range(3): for j in range(3): sourceterm_Lambdabar_rhsU[ i] += -16 * PI * alpha * gammabarUU[i][j] * SD[j] sourceterm_lambda_rhsU = ixp.zerorank1() for i in range(3): sourceterm_lambda_rhsU[i] = sourceterm_Lambdabar_rhsU[i] / rfm.ReU[i]
def BSSN_RHSs(): # Step 1.c: Given the chosen coordinate system, set up # corresponding reference metric and needed # reference metric quantities # The following function call sets up the reference metric # and related quantities, including rescaling matrices ReDD, # ReU, and hatted quantities. rfm.reference_metric() global have_already_called_BSSN_RHSs_function # setting to global enables other modules to see updated value. have_already_called_BSSN_RHSs_function = True # Step 1.d: Set spatial dimension (must be 3 for BSSN, as BSSN is # a 3+1-dimensional decomposition of the general # relativistic field equations) DIM = 3 # Step 1.e: Import all basic (unrescaled) BSSN scalars & tensors import BSSN.BSSN_quantities as Bq Bq.BSSN_basic_tensors() gammabarDD = Bq.gammabarDD AbarDD = Bq.AbarDD LambdabarU = Bq.LambdabarU trK = Bq.trK alpha = Bq.alpha betaU = Bq.betaU # Step 1.f: Import all neeeded rescaled BSSN tensors: aDD = Bq.aDD cf = Bq.cf lambdaU = Bq.lambdaU # Step 2.a.i: Import derivative expressions for betaU defined in the BSSN.BSSN_quantities module: Bq.betaU_derivs() betaU_dD = Bq.betaU_dD betaU_dDD = Bq.betaU_dDD # Step 2.a.ii: Import derivative expression for gammabarDD Bq.gammabar__inverse_and_derivs() gammabarDD_dupD = Bq.gammabarDD_dupD # Step 2.a.iii: First term of \partial_t \bar{\gamma}_{i j} right-hand side: # \beta^k \bar{\gamma}_{ij,k} + \beta^k_{,i} \bar{\gamma}_{kj} + \beta^k_{,j} \bar{\gamma}_{ik} gammabar_rhsDD = ixp.zerorank2() for i in range(DIM): for j in range(DIM): for k in range(DIM): gammabar_rhsDD[i][j] += betaU[k] * gammabarDD_dupD[i][j][k] + betaU_dD[k][i] * gammabarDD[k][j] \ + betaU_dD[k][j] * gammabarDD[i][k] # Step 2.b.i: First import \bar{A}_{ij} = AbarDD[i][j], and its contraction trAbar = \bar{A}^k_k # from BSSN.BSSN_quantities Bq.AbarUU_AbarUD_trAbar_AbarDD_dD() trAbar = Bq.trAbar # Step 2.b.ii: Import detgammabar quantities from BSSN.BSSN_quantities: Bq.detgammabar_and_derivs() detgammabar = Bq.detgammabar detgammabar_dD = Bq.detgammabar_dD # Step 2.b.ii: Compute the contraction \bar{D}_k \beta^k = \beta^k_{,k} + \frac{\beta^k \bar{\gamma}_{,k}}{2 \bar{\gamma}} Dbarbetacontraction = sp.sympify(0) for k in range(DIM): Dbarbetacontraction += betaU_dD[k][ k] + betaU[k] * detgammabar_dD[k] / (2 * detgammabar) # Step 2.b.iii: Second term of \partial_t \bar{\gamma}_{i j} right-hand side: # \frac{2}{3} \bar{\gamma}_{i j} \left (\alpha \bar{A}_{k}^{k} - \bar{D}_{k} \beta^{k}\right ) for i in range(DIM): for j in range(DIM): gammabar_rhsDD[i][j] += sp.Rational(2, 3) * gammabarDD[i][j] * ( alpha * trAbar - Dbarbetacontraction) # Step 2.c: Third term of \partial_t \bar{\gamma}_{i j} right-hand side: # -2 \alpha \bar{A}_{ij} for i in range(DIM): for j in range(DIM): gammabar_rhsDD[i][j] += -2 * alpha * AbarDD[i][j] # Step 3.a: First term of \partial_t \bar{A}_{i j}: # \beta^k \partial_k \bar{A}_{ij} + \partial_i \beta^k \bar{A}_{kj} + \partial_j \beta^k \bar{A}_{ik} # First define AbarDD_dupD: AbarDD_dupD = Bq.AbarDD_dupD # From Bq.AbarUU_AbarUD_trAbar_AbarDD_dD() Abar_rhsDD = ixp.zerorank2() for i in range(DIM): for j in range(DIM): for k in range(DIM): Abar_rhsDD[i][j] += betaU[k] * AbarDD_dupD[i][j][k] + betaU_dD[k][i] * AbarDD[k][j] \ + betaU_dD[k][j] * AbarDD[i][k] # Step 3.b: Second term of \partial_t \bar{A}_{i j}: # - (2/3) \bar{A}_{i j} \bar{D}_{k} \beta^{k} - 2 \alpha \bar{A}_{i k} {\bar{A}^{k}}_{j} + \alpha \bar{A}_{i j} K gammabarUU = Bq.gammabarUU # From Bq.gammabar__inverse_and_derivs() AbarUD = Bq.AbarUD # From Bq.AbarUU_AbarUD_trAbar() for i in range(DIM): for j in range(DIM): Abar_rhsDD[i][j] += -sp.Rational(2, 3) * AbarDD[i][ j] * Dbarbetacontraction + alpha * AbarDD[i][j] * trK for k in range(DIM): Abar_rhsDD[i][j] += -2 * alpha * AbarDD[i][k] * AbarUD[k][j] # Step 3.c.i: Define partial derivatives of \phi in terms of evolved quantity "cf": Bq.phi_and_derivs() phi_dD = Bq.phi_dD phi_dupD = Bq.phi_dupD phi_dDD = Bq.phi_dDD exp_m4phi = Bq.exp_m4phi phi_dBarD = Bq.phi_dBarD # phi_dBarD = Dbar_i phi = phi_dD (since phi is a scalar) phi_dBarDD = Bq.phi_dBarDD # phi_dBarDD = Dbar_i Dbar_j phi (covariant derivative) # Step 3.c.ii: Define RbarDD Bq.RicciBar__gammabarDD_dHatD__DGammaUDD__DGammaU() RbarDD = Bq.RbarDD # Step 3.c.iii: Define first and second derivatives of \alpha, as well as # \bar{D}_i \bar{D}_j \alpha, which is defined just like phi alpha_dD = ixp.declarerank1("alpha_dD") alpha_dDD = ixp.declarerank2("alpha_dDD", "sym01") alpha_dBarD = alpha_dD alpha_dBarDD = ixp.zerorank2() GammabarUDD = Bq.GammabarUDD # Defined in Bq.gammabar__inverse_and_derivs() for i in range(DIM): for j in range(DIM): alpha_dBarDD[i][j] = alpha_dDD[i][j] for k in range(DIM): alpha_dBarDD[i][j] += -GammabarUDD[k][i][j] * alpha_dD[k] # Step 3.c.iv: Define the terms in curly braces: curlybrackettermsDD = ixp.zerorank2() for i in range(DIM): for j in range(DIM): curlybrackettermsDD[i][j] = -2 * alpha * phi_dBarDD[i][j] + 4 * alpha * phi_dBarD[i] * phi_dBarD[j] \ + 2 * alpha_dBarD[i] * phi_dBarD[j] \ + 2 * alpha_dBarD[j] * phi_dBarD[i] \ - alpha_dBarDD[i][j] + alpha * RbarDD[i][j] # Step 3.c.v: Compute the trace: curlybracketterms_trace = sp.sympify(0) for i in range(DIM): for j in range(DIM): curlybracketterms_trace += gammabarUU[i][j] * curlybrackettermsDD[ i][j] # Step 3.c.vi: Third and final term of Abar_rhsDD[i][j]: for i in range(DIM): for j in range(DIM): Abar_rhsDD[i][j] += exp_m4phi * ( curlybrackettermsDD[i][j] - sp.Rational(1, 3) * gammabarDD[i][j] * curlybracketterms_trace) # Step 4: Right-hand side of conformal factor variable "cf". Supported # options include: cf=phi, cf=W=e^(-2*phi) (default), and cf=chi=e^(-4*phi) # \partial_t phi = \left[\beta^k \partial_k \phi \right] <- TERM 1 # + \frac{1}{6} \left (\bar{D}_{k} \beta^{k} - \alpha K \right ) <- TERM 2 global cf_rhs cf_rhs = sp.Rational(1, 6) * (Dbarbetacontraction - alpha * trK) # Term 2 for k in range(DIM): cf_rhs += betaU[k] * phi_dupD[k] # Term 1 # Next multiply to convert phi_rhs to cf_rhs. if par.parval_from_str( "BSSN.BSSN_quantities::EvolvedConformalFactor_cf") == "phi": pass # do nothing; cf_rhs = phi_rhs elif par.parval_from_str( "BSSN.BSSN_quantities::EvolvedConformalFactor_cf") == "W": cf_rhs *= -2 * cf # cf_rhs = -2*cf*phi_rhs elif par.parval_from_str( "BSSN.BSSN_quantities::EvolvedConformalFactor_cf") == "chi": cf_rhs *= -4 * cf # cf_rhs = -4*cf*phi_rhs else: print("Error: EvolvedConformalFactor_cf == " + par.parval_from_str( "BSSN.BSSN_quantities::EvolvedConformalFactor_cf") + " unsupported!") exit(1) # Step 5: right-hand side of trK (trace of extrinsic curvature): # \partial_t K = \beta^k \partial_k K <- TERM 1 # + \frac{1}{3} \alpha K^{2} <- TERM 2 # + \alpha \bar{A}_{i j} \bar{A}^{i j} <- TERM 3 # - - e^{-4 \phi} (\bar{D}_{i} \bar{D}^{i} \alpha + 2 \bar{D}^{i} \alpha \bar{D}_{i} \phi ) <- TERM 4 global trK_rhs # TERM 2: trK_rhs = sp.Rational(1, 3) * alpha * trK * trK trK_dupD = ixp.declarerank1("trK_dupD") for i in range(DIM): # TERM 1: trK_rhs += betaU[i] * trK_dupD[i] for i in range(DIM): for j in range(DIM): # TERM 4: trK_rhs += -exp_m4phi * gammabarUU[i][j] * ( alpha_dBarDD[i][j] + 2 * alpha_dBarD[j] * phi_dBarD[i]) AbarUU = Bq.AbarUU # From Bq.AbarUU_AbarUD_trAbar() for i in range(DIM): for j in range(DIM): # TERM 3: trK_rhs += alpha * AbarDD[i][j] * AbarUU[i][j] # Step 6: right-hand side of \partial_t \bar{\Lambda}^i: # \partial_t \bar{\Lambda}^i = \beta^k \partial_k \bar{\Lambda}^i - \partial_k \beta^i \bar{\Lambda}^k <- TERM 1 # + \bar{\gamma}^{j k} \hat{D}_{j} \hat{D}_{k} \beta^{i} <- TERM 2 # + \frac{2}{3} \Delta^{i} \bar{D}_{j} \beta^{j} <- TERM 3 # + \frac{1}{3} \bar{D}^{i} \bar{D}_{j} \beta^{j} <- TERM 4 # - 2 \bar{A}^{i j} (\partial_{j} \alpha - 6 \partial_{j} \phi) <- TERM 5 # + 2 \alpha \bar{A}^{j k} \Delta_{j k}^{i} <- TERM 6 # - \frac{4}{3} \alpha \bar{\gamma}^{i j} \partial_{j} K <- TERM 7 # Step 6.a: Term 1 of \partial_t \bar{\Lambda}^i: \beta^k \partial_k \bar{\Lambda}^i - \partial_k \beta^i \bar{\Lambda}^k # First we declare \bar{\Lambda}^i and \bar{\Lambda}^i_{,j} in terms of \lambda^i and \lambda^i_{,j} global LambdabarU_dupD # Used on the RHS of the Gamma-driving shift conditions LambdabarU_dupD = ixp.zerorank2() lambdaU_dupD = ixp.declarerank2("lambdaU_dupD", "nosym") for i in range(DIM): for j in range(DIM): LambdabarU_dupD[i][j] = lambdaU_dupD[i][j] * rfm.ReU[i] + lambdaU[ i] * rfm.ReUdD[i][j] global Lambdabar_rhsU # Used on the RHS of the Gamma-driving shift conditions Lambdabar_rhsU = ixp.zerorank1() for i in range(DIM): for k in range(DIM): Lambdabar_rhsU[i] += betaU[k] * LambdabarU_dupD[i][k] - betaU_dD[ i][k] * LambdabarU[k] # Term 1 # Step 6.b: Term 2 of \partial_t \bar{\Lambda}^i = \bar{\gamma}^{jk} (Term 2a + Term 2b + Term 2c) # Term 2a: \bar{\gamma}^{jk} \beta^i_{,kj} Term2aUDD = ixp.zerorank3() for i in range(DIM): for j in range(DIM): for k in range(DIM): Term2aUDD[i][j][k] += betaU_dDD[i][k][j] # Term 2b: \hat{\Gamma}^i_{mk,j} \beta^m + \hat{\Gamma}^i_{mk} \beta^m_{,j} # + \hat{\Gamma}^i_{dj}\beta^d_{,k} - \hat{\Gamma}^d_{kj} \beta^i_{,d} Term2bUDD = ixp.zerorank3() for i in range(DIM): for j in range(DIM): for k in range(DIM): for m in range(DIM): Term2bUDD[i][j][k] += rfm.GammahatUDDdD[i][m][k][j] * betaU[m] \ + rfm.GammahatUDD[i][m][k] * betaU_dD[m][j] \ + rfm.GammahatUDD[i][m][j] * betaU_dD[m][k] \ - rfm.GammahatUDD[m][k][j] * betaU_dD[i][m] # Term 2c: \hat{\Gamma}^i_{dj}\hat{\Gamma}^d_{mk} \beta^m - \hat{\Gamma}^d_{kj} \hat{\Gamma}^i_{md} \beta^m Term2cUDD = ixp.zerorank3() for i in range(DIM): for j in range(DIM): for k in range(DIM): for m in range(DIM): for d in range(DIM): Term2cUDD[i][j][k] += (rfm.GammahatUDD[i][d][j] * rfm.GammahatUDD[d][m][k] \ - rfm.GammahatUDD[d][k][j] * rfm.GammahatUDD[i][m][d]) * betaU[m] Lambdabar_rhsUpieceU = ixp.zerorank1() # Put it all together to get Term 2: for i in range(DIM): for j in range(DIM): for k in range(DIM): Lambdabar_rhsU[i] += gammabarUU[j][k] * (Term2aUDD[i][j][k] + Term2bUDD[i][j][k] + Term2cUDD[i][j][k]) Lambdabar_rhsUpieceU[i] += gammabarUU[j][k] * ( Term2aUDD[i][j][k] + Term2bUDD[i][j][k] + Term2cUDD[i][j][k]) # Step 6.c: Term 3 of \partial_t \bar{\Lambda}^i: # \frac{2}{3} \Delta^{i} \bar{D}_{j} \beta^{j} DGammaU = Bq.DGammaU # From Bq.RicciBar__gammabarDD_dHatD__DGammaUDD__DGammaU() for i in range(DIM): Lambdabar_rhsU[i] += sp.Rational( 2, 3) * DGammaU[i] * Dbarbetacontraction # Term 3 # Step 6.d: Term 4 of \partial_t \bar{\Lambda}^i: # \frac{1}{3} \bar{D}^{i} \bar{D}_{j} \beta^{j} detgammabar_dDD = Bq.detgammabar_dDD # From Bq.detgammabar_and_derivs() Dbarbetacontraction_dBarD = ixp.zerorank1() for k in range(DIM): for m in range(DIM): Dbarbetacontraction_dBarD[m] += betaU_dDD[k][k][m] + \ (betaU_dD[k][m] * detgammabar_dD[k] + betaU[k] * detgammabar_dDD[k][m]) / (2 * detgammabar) \ - betaU[k] * detgammabar_dD[k] * detgammabar_dD[m] / ( 2 * detgammabar * detgammabar) for i in range(DIM): for m in range(DIM): Lambdabar_rhsU[i] += sp.Rational( 1, 3) * gammabarUU[i][m] * Dbarbetacontraction_dBarD[m] # Step 6.e: Term 5 of \partial_t \bar{\Lambda}^i: # - 2 \bar{A}^{i j} (\partial_{j} \alpha - 6 \alpha \partial_{j} \phi) for i in range(DIM): for j in range(DIM): Lambdabar_rhsU[i] += -2 * AbarUU[i][j] * (alpha_dD[j] - 6 * alpha * phi_dD[j]) # Step 6.f: Term 6 of \partial_t \bar{\Lambda}^i: # 2 \alpha \bar{A}^{j k} \Delta^{i}_{j k} DGammaUDD = Bq.DGammaUDD # From RicciBar__gammabarDD_dHatD__DGammaUDD__DGammaU() for i in range(DIM): for j in range(DIM): for k in range(DIM): Lambdabar_rhsU[ i] += 2 * alpha * AbarUU[j][k] * DGammaUDD[i][j][k] # Step 6.g: Term 7 of \partial_t \bar{\Lambda}^i: # -\frac{4}{3} \alpha \bar{\gamma}^{i j} \partial_{j} K trK_dD = ixp.declarerank1("trK_dD") for i in range(DIM): for j in range(DIM): Lambdabar_rhsU[i] += -sp.Rational( 4, 3) * alpha * gammabarUU[i][j] * trK_dD[j] # Step 7: Rescale the RHS quantities so that the evolved # variables are smooth across coord singularities global h_rhsDD, a_rhsDD, lambda_rhsU h_rhsDD = ixp.zerorank2() a_rhsDD = ixp.zerorank2() lambda_rhsU = ixp.zerorank1() for i in range(DIM): lambda_rhsU[i] = Lambdabar_rhsU[i] / rfm.ReU[i] for j in range(DIM): h_rhsDD[i][j] = gammabar_rhsDD[i][j] / rfm.ReDD[i][j] a_rhsDD[i][j] = Abar_rhsDD[i][j] / rfm.ReDD[i][j]
def BSSN_constraints(add_T4UUmunu_source_terms=False): # Step 1.a: Set spatial dimension (must be 3 for BSSN, as BSSN is # a 3+1-dimensional decomposition of the general # relativistic field equations) DIM = 3 # Step 1.b: Given the chosen coordinate system, set up # corresponding reference metric and needed # reference metric quantities # The following function call sets up the reference metric # and related quantities, including rescaling matrices ReDD, # ReU, and hatted quantities. rfm.reference_metric() # Step 2: Hamiltonian constraint. # First declare all needed variables Bq.declare_BSSN_gridfunctions_if_not_declared_already() # Sets trK Bq.BSSN_basic_tensors() # Sets AbarDD Bq.gammabar__inverse_and_derivs() # Sets gammabarUU Bq.AbarUU_AbarUD_trAbar_AbarDD_dD() # Sets AbarUU and AbarDD_dD Bq.RicciBar__gammabarDD_dHatD__DGammaUDD__DGammaU() # Sets RbarDD Bq.phi_and_derivs() # Sets phi_dBarD & phi_dBarDD ############################### ############################### # HAMILTONIAN CONSTRAINT ############################### ############################### # Term 1: 2/3 K^2 global H H = sp.Rational(2, 3) * Bq.trK**2 # Term 2: -A_{ij} A^{ij} for i in range(DIM): for j in range(DIM): H += -Bq.AbarDD[i][j] * Bq.AbarUU[i][j] # Term 3a: trace(Rbar) Rbartrace = sp.sympify(0) for i in range(DIM): for j in range(DIM): Rbartrace += Bq.gammabarUU[i][j] * Bq.RbarDD[i][j] # Term 3b: -8 \bar{\gamma}^{ij} \bar{D}_i \phi \bar{D}_j \phi = -8*phi_dBar_times_phi_dBar # Term 3c: -8 \bar{\gamma}^{ij} \bar{D}_i \bar{D}_j \phi = -8*phi_dBarDD_contraction phi_dBar_times_phi_dBar = sp.sympify(0) # Term 3b phi_dBarDD_contraction = sp.sympify(0) # Term 3c for i in range(DIM): for j in range(DIM): phi_dBar_times_phi_dBar += Bq.gammabarUU[i][j] * Bq.phi_dBarD[ i] * Bq.phi_dBarD[j] phi_dBarDD_contraction += Bq.gammabarUU[i][j] * Bq.phi_dBarDD[i][j] # Add Term 3: H += Bq.exp_m4phi * (Rbartrace - 8 * (phi_dBar_times_phi_dBar + phi_dBarDD_contraction)) if add_T4UUmunu_source_terms: M_PI = par.Cparameters("#define", thismodule, "M_PI", "") # M_PI is pi as defined in C BTmunu.define_BSSN_T4UUmunu_rescaled_source_terms() rho = BTmunu.rho H += -16 * M_PI * rho # FIXME: ADD T4UUmunu SOURCE TERMS TO MOMENTUM CONSTRAINT! # Step 3: M^i, the momentum constraint ############################### ############################### # MOMENTUM CONSTRAINT ############################### ############################### # SEE Tutorial-BSSN_constraints.ipynb for full documentation. global MU MU = ixp.zerorank1() # Term 2: 6 A^{ij} \partial_j \phi: for i in range(DIM): for j in range(DIM): MU[i] += 6 * Bq.AbarUU[i][j] * Bq.phi_dD[j] # Term 3: -2/3 \bar{\gamma}^{ij} K_{,j} trK_dD = ixp.declarerank1( "trK_dD") # Not defined in BSSN_RHSs; only trK_dupD is defined there. for i in range(DIM): for j in range(DIM): MU[i] += -sp.Rational(2, 3) * Bq.gammabarUU[i][j] * trK_dD[j] # First define aDD_dD: aDD_dD = ixp.declarerank3("aDD_dD", "sym01") # Then evaluate the conformal covariant derivative \bar{D}_j \bar{A}_{lm} AbarDD_dBarD = ixp.zerorank3() for i in range(DIM): for j in range(DIM): for k in range(DIM): AbarDD_dBarD[i][j][k] = Bq.AbarDD_dD[i][j][k] for l in range(DIM): AbarDD_dBarD[i][j][ k] += -Bq.GammabarUDD[l][k][i] * Bq.AbarDD[l][j] AbarDD_dBarD[i][j][ k] += -Bq.GammabarUDD[l][k][j] * Bq.AbarDD[i][l] # Term 1: Contract twice with the metric to make \bar{D}_{j} \bar{A}^{ij} for i in range(DIM): for j in range(DIM): for k in range(DIM): for l in range(DIM): MU[i] += Bq.gammabarUU[i][k] * Bq.gammabarUU[j][ l] * AbarDD_dBarD[k][l][j] # Finally, we multiply by e^{-4 phi} and rescale the momentum constraint: for i in range(DIM): MU[i] *= Bq.exp_m4phi / rfm.ReU[i]
def ScalarField_RHSs(): # Step B.4: Set spatial dimension (must be 3 for BSSN, as BSSN is # a 3+1-dimensional decomposition of the general # relativistic field equations) DIM = 3 # Step B.5: Import all basic (unrescaled) BSSN scalars & tensors Bq.BSSN_basic_tensors() trK = Bq.trK alpha = Bq.alpha betaU = Bq.betaU Bq.gammabar__inverse_and_derivs() gammabarUU = Bq.gammabarUU global sf_rhs, sfM_rhs # Step B.5.a: Declare grid functions for varphi and Pi sf, sfM = sfgfs.declare_scalar_field_gridfunctions_if_not_declared_already( ) # Step 2.a: Add Term 1 to sf_rhs: -alpha*Pi sf_rhs = -alpha * sfM # Step 2.b: Add Term 2 to sf_rhs: beta^{i}\partial_{i}\varphi sf_dupD = ixp.declarerank1("sf_dupD") for i in range(DIM): sf_rhs += betaU[i] * sf_dupD[i] # Step 3a: Add Term 1 to sfM_rhs: alpha * K * Pi sfM_rhs = alpha * trK * sfM # Step 3b: Add Term 2 to sfM_rhs: beta^{i}\partial_{i}Pi sfM_dupD = ixp.declarerank1("sfM_dupD") for i in range(DIM): sfM_rhs += betaU[i] * sfM_dupD[i] # Step 3c: Adding Term 3 to sfM_rhs # Step 3c.i: Term 3a: gammabar^{ij}\partial_{i}\alpha\partial_{j}\varphi alpha_dD = ixp.declarerank1("alpha_dD") sf_dD = ixp.declarerank1("sf_dD") sfMrhsTerm3 = sp.sympify(0) for i in range(DIM): for j in range(DIM): sfMrhsTerm3 += -gammabarUU[i][j] * alpha_dD[i] * sf_dD[j] # Step 3c.ii: Term 3b: \alpha*gammabar^{ij}\partial_{i}\partial_{j}\varphi sf_dDD = ixp.declarerank2("sf_dDD", "sym01") for i in range(DIM): for j in range(DIM): sfMrhsTerm3 += -alpha * gammabarUU[i][j] * sf_dDD[i][j] # Step 3c.iii: Term 3c: 2*alpha*gammabar^{ij}\partial_{j}\varphi\partial_{i}\phi Bq.phi_and_derivs( ) # sets exp^{-4phi} = exp_m4phi and \partial_{i}phi = phi_dD[i] for i in range(DIM): for j in range(DIM): sfMrhsTerm3 += -2 * alpha * gammabarUU[i][j] * sf_dD[ j] * Bq.phi_dD[i] # Step 3c.iv: Multiplying Term 3 by e^{-4phi} and adding it to sfM_rhs sfMrhsTerm3 *= Bq.exp_m4phi sfM_rhs += sfMrhsTerm3 # Step 3d: Adding Term 4 to sfM_rhs # Step 3d.i: Term 4a: \alpha \bar\Lambda^{i}\partial_{i}\varphi LambdabarU = Bq.LambdabarU sfMrhsTerm4 = sp.sympify(0) for i in range(DIM): sfMrhsTerm4 += alpha * LambdabarU[i] * sf_dD[i] # Step 3d.ii: Evaluating \bar\gamma^{ij}\hat\Gamma^{k}_{ij} GammahatUDD = rfm.GammahatUDD gammabarGammahatContractionU = ixp.zerorank1() for k in range(DIM): for i in range(DIM): for j in range(DIM): gammabarGammahatContractionU[ k] += gammabarUU[i][j] * GammahatUDD[k][i][j] # Step 3d.iii: Term 4b: \alpha \bar\gamma^{ij}\hat\Gamma^{k}_{ij}\partial_{k}\varphi for i in range(DIM): sfMrhsTerm4 += alpha * gammabarGammahatContractionU[i] * sf_dD[i] # Step 3d.iii: Multplying Term 4 by e^{-4phi} and adding it to sfM_rhs sfMrhsTerm4 *= Bq.exp_m4phi sfM_rhs += sfMrhsTerm4 return