Line data    Source code

       1            0 : // Distributed under the MIT License.
       2              : // See LICENSE.txt for details.
       3              : 
       4              : #pragma once
       5              : 
       6              : #include <cstddef>
       7              : 
       8              : #include "DataStructures/Tensor/TypeAliases.hpp"
       9              : #include "Utilities/Gsl.hpp"
      10              : 
      11              : namespace gh {
      12              : namespace gauges {
      13              : namespace DampedHarmonicGauge_detail {
      14              : /*
      15              :  * Spatial weight function used in the damped harmonic gauge source
      16              :  * function.
      17              :  *
      18              :  * The spatial weight function is:
      19              :  * \f{align*}{
      20              :  *   W(x^i) = \exp(- (r / \sigma_r)^2),
      21              :  * \f}
      22              :  *
      23              :  * where \f$r=\sqrt{x^i\delta_{ij}x^j}\f$ is the coordinate radius, and
      24              :  * \f$\sigma_r\f$ is the width of the Gaussian.
      25              :  *
      26              :  * This function can be written with an extra factor inside the exponent in
      27              :  * literature, e.g. \cite Deppe2018uye. We absorb that in \f$\sigma_r\f$.
      28              :  */
      29              : template <typename DataType, size_t SpatialDim, typename Frame>
      30              : void spatial_weight_function(gsl::not_null<Scalar<DataType>*> weight,
      31              :                              const tnsr::I<DataType, SpatialDim, Frame>& coords,
      32              :                              double sigma_r);
      33              : 
      34              : /*
      35              :  * Spacetime derivatives of the spatial weight function that enters the
      36              :  * damped harmonic gauge source function.
      37              :  *
      38              :  * Compute the derivatives:
      39              :  * \f{align*}{
      40              :  * \partial_a W(x^i)= \partial_a \exp(- (r/\sigma_r)^2)
      41              :  *                  = (-2 * x^i / \sigma_r^2) * exp(-(r/\sigma_r)^2)
      42              :  * \f}
      43              :  *
      44              :  * where \f$r=\sqrt{x^i\delta_{ij}x^j}\f$ is the coordinate radius, and
      45              :  * \f$\sigma_r\f$ is the width of the Gaussian. Since the weight function is
      46              :  * spatial, the time derivative is always zero.
      47              :  */
      48              : template <typename DataType, size_t SpatialDim, typename Frame>
      49              : void spacetime_deriv_of_spatial_weight_function(
      50              :     gsl::not_null<tnsr::a<DataType, SpatialDim, Frame>*> d4_weight,
      51              :     const tnsr::I<DataType, SpatialDim, Frame>& coords, double sigma_r,
      52              :     const Scalar<DataType>& weight_function);
      53              : 
      54              : /*
      55              :  * The log factor that appears in damped harmonic gauge source function.
      56              :  *
      57              :  * Calculates:  \f$ logF = \mathrm{log}(\gamma^p/\alpha) \f$.
      58              :  */
      59              : template <typename DataType>
      60              : void log_factor_metric_lapse(gsl::not_null<Scalar<DataType>*> logfac,
      61              :                              const Scalar<DataType>& lapse,
      62              :                              const Scalar<DataType>& sqrt_det_spatial_metric,
      63              :                              double exponent);
      64              : 
      65              : template <typename DataType>
      66              : Scalar<DataType> log_factor_metric_lapse(
      67              :     const Scalar<DataType>& lapse,
      68              :     const Scalar<DataType>& sqrt_det_spatial_metric, double exponent);
      69              : 
      70              : }  // namespace DampedHarmonicGauge_detail
      71              : }  // namespace gauges
      72              : }  // namespace gh