SpECTRE  v2026.06.30
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Cce::ComputeBondiIntegrand< Tags::Integrand< Tags::BondiU > > Struct Reference

Computes the integrand (right-hand side) of the equation which determines the radial (y) dependence of the Bondi quantity \(U\). More...

#include <Equations.hpp>

Public Types

using pre_swsh_derivative_tags
using swsh_derivative_tags = tmpl::list<>
using integration_independent_tags = tmpl::list<Tags::BondiK, Tags::BondiR>
using temporary_tags = tmpl::list<>
using return_tags
using argument_tags

Static Public Member Functions

template<typename... Args>
static void apply (const gsl::not_null< Scalar< SpinWeighted< ComplexDataVector, 1 > > * > regular_integrand_for_u, const Args &... args)

Detailed Description

Computes the integrand (right-hand side) of the equation which determines the radial (y) dependence of the Bondi quantity \(U\).

Details

The quantity \(U\) is defined via the Bondi form of the metric:

\[ds^2 = - \left(e^{2 \beta} (1 + r W) - r^2 h_{AB} U^A U^B\right) du^2 - 2 e^{2 \beta} du dr - 2 r^2 h_{AB} U^B du dx^A + r^2 h_{A B} dx^A dx^B. \]

Additional quantities \(J\) and \(K\) are defined using a spherical angular dyad \(q^A\):

\[ J \equiv h_{A B} q^A q^B, K \equiv h_{A B} q^A \bar{q}^B,\]

and \(Q\) is defined as a supplemental variable for radial integration of \(U\):

\[ Q_A = r^2 e^{-2\beta} h_{AB} \partial_r U^B\]

and \(U = U_A q^A\). See [21] [94] for full details.

We write the equations of motion in the compactified coordinate \( y \equiv 1 - 2 R/ r\), where \(r(u, \theta, \phi)\) is the Bondi radius of the \(y=\) constant surface and \(R(u,\theta,\phi)\) is the Bondi radius of the worldtube. The equation which determines \(U\) on a surface of constant \(u\) given \(J\), \(\beta\), and \(Q\) on the same surface is written as

\[\partial_y U = \frac{e^{2\beta}}{2 R} (K Q - J \bar{Q}). \]

Member Typedef Documentation

◆ argument_tags

Initial value:
tmpl::append<pre_swsh_derivative_tags, swsh_derivative_tags,
integration_independent_tags>

◆ pre_swsh_derivative_tags

using Cce::ComputeBondiIntegrand< Tags::Integrand< Tags::BondiU > >::pre_swsh_derivative_tags
Initial value:
tmpl::list<Tags::Exp2Beta, Tags::BondiJ, Tags::BondiQ>

◆ return_tags

Initial value:
tmpl::append<tmpl::list<Tags::Integrand<Tags::BondiU>>, temporary_tags>

The documentation for this struct was generated from the following file:
  • src/Evolution/Systems/Cce/Equations.hpp