Orbiting Scalar Charges

Gabrielle Allen

Date

Abstract

1 Introduction

This thorn provides a source term to the scalar field evolution for two rotating binary charges.

2 Physical System

The 3D scalar wave equation with a source term ρ(t,x,y,z) is written

ϕ = 4πρ

Each scalar source with charge Q and radius R contributes

ρ = 3Q 4πR3

3 Numerical Implementation

The only involved part of this thorn arise in working out where the sources are located (if at all) on each local grid for a multiprocessor run. The source terms are not numerically evolved, but are calculated exactly, based on the physical time and their orbital velocity.

A routine is scheduled to run after the homogeneous equation for the scalar field has been evolved, and simply updates the value of the scalar field by adding on the source contribution.

4 Parameters




binary_charge
Scope: private  REAL



Description: Charge of source



Range   Default: 0.1
:
No restriction






binary_omega
Scope: private  REAL



Description: Frequency of the circular binary orbit



Range   Default: 2.0
0.0:
Some positive value






binary_radius
Scope: private  REAL



Description: Radius of the circular binary orbit



Range   Default: 2.0
0.0:
Some positive value






binary_size
Scope: private  REAL



Description: Radial extension of the binary source



Range   Default: 0.5
0.0:
Some positive value






binary_verbose
Scope: private  KEYWORD



Description: Rotating binary source verbose



Range   Default: no
yes
Info on charge location/extension on first iteration
debug
Info on charge location/extension on all iterations
no
no output



5 Interfaces

General

Implements:

binarysource

Inherits:

wavetoy

grid

6 Schedule

This section lists all the variables which are assigned storage by thorn CactusWave/WaveBinarySource. Storage can either last for the duration of the run (Always means that if this thorn is activated storage will be assigned, Conditional means that if this thorn is activated storage will be assigned for the duration of the run if some condition is met), or can be turned on for the duration of a schedule function.

Storage

NONE

Scheduled Functions

CCTK_EVOL

  wavebinaryc

  provide binary source during evolution (c)

 

 After: wavetoy_evolution
 Language:c
 Storage: wavetoy::scalarevolve[1]
 Type: function