control_system::ControlErrors::Skew Struct Reference

Control error in the for the domain::CoordinateMaps::TimeDependent::Skew map. More...

#include <Skew.hpp>

Public Types
using	object_centers = domain::object_list<>
using	options = implementation defined

Public Member Functions
	Skew (Skew &&rhs)=default
Skew &	operator= (Skew &&rhs)=default
	Skew (const Skew &)
Skew &	operator= (const Skew &)
std::optional< double >	get_suggested_timescale () const
	Returns the internal suggested timescale. A std::nullopt means that no timescale is suggested.
void	reset ()
	Resets the internal suggested timescale to nullopt.
void	pup (PUP::er &p)
template<typename Metavariables , typename... TupleTags>
DataVector	operator() (const ::TimescaleTuner< true > &, const Parallel::GlobalCache< Metavariables > &cache, const double time, const std::string &function_of_time_name, const tuples::TaggedTuple< TupleTags... > &measurements)

Static Public Attributes
static constexpr Options::String	help

Detailed Description

Control error in the for the domain::CoordinateMaps::TimeDependent::Skew map.

Details

Computes the error in the map parameters $F_y(t)$ and $F_z(t)$ of the Skew using a modified version of Eq. (71) from [94]. This modified control error is

$$\begin{array}{}\text{(1)}& Q_{F_j}=g\left(\frac{w_A{\mathrm{\Theta }}_A^j+w_B{\mathrm{\Theta }}_B^j}{w_A+w_B}\right)-(1-g)F_j\end{array}$$

where the falloff function is assumed to be $W(\overrightarrow{x})\approx 1$ from the Skew map, ${\mathrm{\Theta }}_H^j$ are the inclination angles between the $x$-axis and the normal to the horizon at the intersection point $x_H^{\text{Int}}$ between the $x$-axis and the horizon, $w_A$ and $w_B$ are averaging weights defined by

$$\begin{array}{}\text{(2)}& w_H=\exp (-\frac{x_C^0-x_H^{\text{Int}}}{x_C^0-C_H^0})\end{array}$$

with $C_H^0$ being the centers of the excision boundaries, and finally with

$$\begin{array}{}\text{(3)}& g=\frac{1}{2}(1-\tanh (10\frac{x_A^{\text{Int}}-x_B^{\text{Int}}}{C_A^0-C_B^0}-5)).\end{array}$$

This transition function $g$ is meant to only activate skew control when the black holes are close to merger to avoid adverse effects with junk radiation. If $g<0.0025$, then we turn skew control off completely and the control error just becomes

$$\begin{array}{}\text{(4)}& Q_{F_j}=-F_j.\end{array}$$

This threshold value of $g=0.0025$ was chosen in SpEC and seems to work well.

Requirements:

• This control error requires that there be exactly two objects in the simulation
• Currently both these objects must be black holes
• Currently this control system can only be used with the Skew control system

Member Data Documentation

help

constexpr Options::String control_system::ControlErrors::Skew::help

staticconstexpr

Initial value:

{
      "Computes the control error for skew control."}

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

• src/ControlSystem/ControlErrors/Skew.hpp