SpECTRE  v2021.11.01
Cce::ComputeBondiIntegrand< Tags::PoleOfIntegrand< Tags::BondiQ > > Struct Reference

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

#include <Equations.hpp>

Public Types

using pre_swsh_derivative_tags = tmpl::list<>
 
using swsh_derivative_tags = tmpl::list< Spectral::Swsh::Tags::Derivative< Tags::BondiBeta, Spectral::Swsh::Tags::Eth > >
 
using integration_independent_tags = tmpl::list<>
 
using temporary_tags = tmpl::list<>
 
using return_tags = tmpl::append< tmpl::list< Tags::PoleOfIntegrand< Tags::BondiQ > >, temporary_tags >
 
using argument_tags = tmpl::append< pre_swsh_derivative_tags, swsh_derivative_tags, integration_independent_tags >
 

Static Public Member Functions

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

Detailed Description

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

Details

The quantity \(Q\) 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 \(Q = Q_A q^A\). See [13] [54] 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 \(Q\) on a surface of constant \(u\) given \(J\) and \(\beta\) on the same surface is written as

\[(1 - y) \partial_y Q + 2 Q = A_Q + (1 - y) B_Q.\]

We refer to \(A_Q\) as the "pole part" of the integrand and \(B_Q\) as the "regular part". The pole part is computed by this function, and has the expression

\[A_Q = -4 \eth \beta.\]


The documentation for this struct was generated from the following file: