BilaplacianVarForm.hpp

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#pragma once
 
#include <polyfem/varforms/VarForm.hpp>
 
#include <polyfem/assembler/Assembler.hpp>
#include <polyfem/assembler/RhsAssembler.hpp>
 
namespace polysolve::linear
{
    class Solver;
}
 
namespace polyfem::varform
{
    class BilaplacianVarForm : public VarForm
    {
        friend class polyfem::test::VarFormTestAccess;
 
    public:
        std::string name() const override { return "Bilaplacian"; }
 
        void init(const std::string &formulation, const Units &units, const json &args, const std::string &out_path) override;
        void save_json(const Eigen::MatrixXd &solution, std::ostream &out) const override;
        void export_data(const Eigen::MatrixXd &solution) const override;
        io::OutputSpace output_space() const override;
        io::OutStatsData compute_errors(const Eigen::MatrixXd &solution) override;
 
        std::vector<io::OutputField> output_fields(
            const io::OutputSample &sample,
            const Eigen::MatrixXd &solution,
            const io::OutputFieldOptions &options) const override;
 
    private:
        void reset() override;
        void load_mesh(const mesh::Mesh &mesh, const json &args) override;
        void build_basis(mesh::Mesh &mesh, const bool iso_parametric, const json &args) override;
        void assemble_rhs(const mesh::Mesh &mesh) override;
        void assemble_mass_mat(const mesh::Mesh &mesh, const json &args) override;
        void solve_problem(Eigen::MatrixXd &sol) override;
 
        int stacked_ndof() const;
        void prepare_initial_solution(Eigen::MatrixXd &sol) const;
        void split_solution(const Eigen::MatrixXd &stacked, Eigen::MatrixXd &primary, Eigen::MatrixXd &pressure) const;
        void build_stiffness_mat(StiffnessMatrix &stiffness);
        void solve_linear_system(
            const std::unique_ptr<polysolve::linear::Solver> &solver,
            StiffnessMatrix &A,
            Eigen::VectorXd &b,
            const bool compute_spectrum,
            Eigen::MatrixXd &sol);
        void solve_static_linear(Eigen::MatrixXd &sol);
        void solve_transient_linear(Eigen::MatrixXd &sol);
 
        void build_rhs_assembler() override
        {
            rhs_assembler_ = build_rhs_assembler(space_.n_bases, space_.basis_list(), mass_ass_vals_cache_);
        }
 
        std::shared_ptr<assembler::RhsAssembler> build_rhs_assembler(
            const int n_bases,
            const std::vector<basis::ElementBases> &bases,
            const assembler::AssemblyValsCache &ass_vals_cache);
 
        FESpace space_;
        FESpace pressure_space_;
 
        VarFormBoundaryState boundary_;
        VarFormBoundaryState pressure_boundary_;
 
        assembler::AssemblyValsCache ass_vals_cache_;
        assembler::AssemblyValsCache pressure_ass_vals_cache_;
        assembler::AssemblyValsCache mass_ass_vals_cache_;
        assembler::AssemblyValsCache pure_mass_ass_vals_cache_;
 
        std::shared_ptr<assembler::RhsAssembler> rhs_assembler_;
 
        StiffnessMatrix mass_;
        StiffnessMatrix pure_mass_;
 
        double avg_mass_ = 0;
        Eigen::MatrixXd rhs_;
 
        std::shared_ptr<assembler::Assembler> primary_assembler_ = nullptr;
        std::shared_ptr<assembler::Mass> mass_assembler_ = nullptr;
        std::shared_ptr<assembler::HRZMass> pure_mass_assembler_ = nullptr;
        std::shared_ptr<assembler::MixedAssembler> mixed_assembler_ = nullptr;
        std::shared_ptr<assembler::Assembler> pressure_assembler_ = nullptr;
 
        double t0 = 0;
        int time_steps = 0;
        double dt = 0;
        std::shared_ptr<time_integrator::ImplicitTimeIntegrator> time_integrator;
    };
} // namespace polyfem::varform