Line data    Source code

       1             : //* This file is part of the MOOSE framework
       2             : //* https://mooseframework.inl.gov
       3             : //*
       4             : //* All rights reserved, see COPYRIGHT for full restrictions
       5             : //* https://github.com/idaholab/moose/blob/master/COPYRIGHT
       6             : //*
       7             : //* Licensed under LGPL 2.1, please see LICENSE for details
       8             : //* https://www.gnu.org/licenses/lgpl-2.1.html
       9             : 
      10             : #pragma once
      11             : 
      12             : #include "ExplicitTimeIntegrator.h"
      13             : 
      14             : // Forward declarations
      15             : namespace libMesh
      16             : {
      17             : template <typename T>
      18             : class SparseMatrix;
      19             : }
      20             : 
      21             : /**
      22             :  * Implements a form of the central difference time integrator that calculates acceleration directly
      23             :  * from the residual forces.
      24             :  */
      25             : class ExplicitMixedOrder : public ExplicitTimeIntegrator
      26             : {
      27             : public:
      28             :   static InputParameters validParams();
      29             : 
      30             :   ExplicitMixedOrder(const InputParameters & parameters);
      31             : 
      32           0 :   virtual int order() override { return 1; }
      33             :   virtual void computeTimeDerivatives() override;
      34             : 
      35             :   virtual void solve() override;
      36             :   virtual void postResidual(NumericVector<Number> & residual) override;
      37         738 :   virtual bool overridesSolve() const override { return true; }
      38             : 
      39         369 :   virtual void postSolve() override
      40             :   { // Once we have the new solution, we want to adanceState to make sure the
      41             :     // coupling between the solution and the computed material properties is kept correctly.
      42         369 :     _fe_problem.advanceState();
      43         369 :   }
      44         369 :   virtual bool advancesProblemState() const override { return true; }
      45             : 
      46             :   virtual bool performExplicitSolve(SparseMatrix<Number> & mass_matrix) override;
      47             : 
      48           0 :   void computeADTimeDerivatives(ADReal &, const dof_id_type &, ADReal &) const override
      49             :   {
      50           0 :     mooseError("NOT SUPPORTED");
      51             :   }
      52             :   virtual void init() override;
      53             : 
      54             :   virtual void meshChanged() override;
      55             : 
      56             :   enum TimeOrder
      57             :   {
      58             :     FIRST,
      59             :     SECOND
      60             :   };
      61             : 
      62             :   /**
      63             :    * Retrieve the order of the highest time derivative of a variable.
      64             :    * @return Returns the time order enum of this variable.
      65             :    */
      66             :   TimeOrder findVariableTimeOrder(unsigned int var_num) const;
      67             : 
      68             : protected:
      69             :   /// compile the dof indices for first and second order in time variables
      70             :   void updateDOFIndices();
      71             : 
      72             :   virtual TagID massMatrixTagID() const override;
      73             : 
      74             :   /// Evaluate the RHS residual
      75             :   virtual void evaluateRHSResidual();
      76             : 
      77             :   /// Whether we are reusing the mass matrix
      78             :   const bool & _constant_mass;
      79             : 
      80             :   /**
      81             :    * Must be set to true to use adaptivity with a constant mass
      82             :    * matrix. This will recompute the mass matrix when the mesh changes. The user must make sure that
      83             :    * the underlying material density stays constant, otherwise simulation results will depend on
      84             :    * adaptivity.
      85             :    */
      86             :   const bool & _recompute_mass_matrix_on_mesh_change;
      87             : 
      88             :   /// Whether the mesh changed just before the current solve
      89             :   bool _mesh_changed;
      90             : 
      91             :   /// Mass matrix name
      92             :   const TagName & _mass_matrix_name;
      93             : 
      94             :   /// Lumped mass matrix
      95             :   NumericVector<Real> * _mass_matrix_lumped;
      96             : 
      97             :   /// The older solution
      98             :   const NumericVector<Number> & _solution_older;
      99             : 
     100             :   // Variables that forward Euler time integration will be used for
     101             :   std::unordered_set<unsigned int> & _vars_first;
     102             : 
     103             :   // local dofs that will have forward euler time integration
     104             :   std::vector<dof_id_type> & _local_first_order_indices;
     105             : 
     106             :   // Variables that central difference time integration will be used for
     107             :   std::unordered_set<unsigned int> & _vars_second;
     108             : 
     109             :   // local dofs that will have central difference time integration
     110             :   std::vector<dof_id_type> & _local_second_order_indices;
     111             : 
     112             :   /**
     113             :    * Helper function that actually does the math for computing the time derivative
     114             :    */
     115             :   template <typename T, typename T2, typename T3, typename T4>
     116             :   void
     117             :   computeTimeDerivativeHelper(T & u_dot, T2 & u_dotdot, const T3 & u_old, const T4 & u_older) const;
     118             : 
     119             :   void computeICs();
     120             : };
     121             : 
     122             : template <typename T, typename T2, typename T3, typename T4>
     123             : void
     124             : ExplicitMixedOrder::computeTimeDerivativeHelper(T & u_dot,
     125             :                                                 T2 & u_dotdot,
     126             :                                                 const T3 & u_old,
     127             :                                                 const T4 & u_older) const
     128             : {
     129             :   // computing first derivative
     130             :   // using the Central Difference method
     131             :   // u_dot_old = (first_term - second_term) / 2 / dt
     132             :   //       first_term = u
     133             :   //      second_term = u_older
     134             :   u_dot -= u_older; // 'older than older' solution
     135             :   u_dot *= 1.0 / (2.0 * _dt);
     136             : 
     137             :   // computing second derivative
     138             :   // using the Central Difference method
     139             :   // u_dotdot_old = (first_term - second_term + third_term) / dt / dt
     140             :   //       first_term = u
     141             :   //      second_term = 2 * u_old
     142             :   //       third_term = u_older
     143             :   u_dotdot -= u_old;
     144             :   u_dotdot -= u_old;
     145             :   u_dotdot += u_older;
     146             :   u_dotdot *= 1.0 / (_dt * _dt);
     147             : }