Line data    Source code

       1             : /**********************************************************************/
       2             : /*                    DO NOT MODIFY THIS HEADER                       */
       3             : /*             Swift, a Fourier spectral solver for MOOSE             */
       4             : /*                                                                    */
       5             : /*            Copyright 2024 Battelle Energy Alliance, LLC            */
       6             : /*                        ALL RIGHTS RESERVED                         */
       7             : /**********************************************************************/
       8             : 
       9             : #include "FFTSemiImplicit.h"
      10             : #include "TensorProblem.h"
      11             : #include "DomainAction.h"
      12             : 
      13             : registerMooseObject("SwiftApp", FFTSemiImplicit);
      14             : 
      15             : InputParameters
      16           0 : FFTSemiImplicit::validParams()
      17             : {
      18           0 :   InputParameters params = TensorTimeIntegrator::validParams();
      19           0 :   params.addClassDescription("Semi-implicit time integrator.");
      20           0 :   params.addRequiredParam<TensorInputBufferName>(
      21             :       "reciprocal_buffer", "Buffer with the reciprocal of the integrated buffer");
      22           0 :   params.addRequiredParam<TensorInputBufferName>(
      23             :       "linear_reciprocal", "Buffer with the reciprocal of the linear prefactor (e.g. kappa*k^2)");
      24           0 :   params.addRequiredParam<TensorInputBufferName>(
      25             :       "nonlinear_reciprocal", "Buffer with the reciprocal of the non-linear contribution");
      26           0 :   params.addParam<unsigned int>(
      27           0 :       "history_size", 1, "How many old states to use (determines time integration order).");
      28           0 :   return params;
      29           0 : }
      30             : 
      31           0 : FFTSemiImplicit::FFTSemiImplicit(const InputParameters & parameters)
      32             :   : TensorTimeIntegrator<>(parameters),
      33           0 :     _history_size(getParam<unsigned int>("history_size")),
      34           0 :     _reciprocal_buffer(getInputBuffer("reciprocal_buffer")),
      35           0 :     _linear_reciprocal(getInputBuffer("linear_reciprocal")),
      36           0 :     _non_linear_reciprocal(getInputBuffer("nonlinear_reciprocal")),
      37           0 :     _old_reciprocal_buffer(getBufferOld("reciprocal_buffer", _history_size)),
      38           0 :     _old_non_linear_reciprocal(getBufferOld("nonlinear_reciprocal", _history_size))
      39             : {
      40           0 : }
      41             : 
      42             : void
      43           0 : FFTSemiImplicit::computeBuffer()
      44             : {
      45           0 :   const auto n_old = std::min(_old_reciprocal_buffer.size(), _old_non_linear_reciprocal.size());
      46             : 
      47             :   torch::Tensor ubar;
      48           0 :   if (n_old == 0)
      49             :     // compute FFT time update (1st order)
      50           0 :     ubar = (_reciprocal_buffer + _sub_dt * _non_linear_reciprocal) / (1.0 - _sub_dt * _linear_reciprocal);
      51             : 
      52             :   if (n_old >= 1)
      53             :     // compute FFT time update (2nd order) - this probably breaks for adaptive dt!
      54             :     // ubar = (4.0 * _reciprocal_buffer - _old_reciprocal_buffer[0] +
      55             :     //         (2.0 * _sub_dt) * (2.0 * _non_linear_reciprocal - _old_non_linear_reciprocal[0])) /
      56             :     //        (3.0 - (2.0 * _sub_dt) * _linear_reciprocal);
      57           0 :     ubar = (_reciprocal_buffer +
      58           0 :             _sub_dt / 2.0 * (3.0 * _non_linear_reciprocal - _old_non_linear_reciprocal[0])) /
      59           0 :            (1.0 - _sub_dt * _linear_reciprocal);
      60             : 
      61           0 :   _u = _domain.ifft(ubar);
      62           0 : }