NavierStokesFSIVarForm.hpp

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#pragma once
 
#include <polyfem/mesh/MeshUtils.hpp>
#include <polyfem/varforms/FluidVarForm.hpp>
 
namespace polyfem::solver
{
    class ElasticForm;
    class FSIInterfaceForm;
    class NavierStokesFSIAveragePressureForm;
    class NavierStokesFSIForm;
} // namespace polyfem::solver
 
namespace polyfem::varform
{
    class NonlinearElasticTransientVarForm;
 
    class NavierStokesFSIVarForm : public FluidVarForm
    {
        friend class polyfem::test::VarFormTestAccess;
 
    public:
        using FluidVarForm::FluidVarForm;
        std::string name() const override { return "NavierStokesFSI"; }
        void init(const std::string &formulation, const Units &units, const json &args, const std::string &out_path) override;
        void serialize_checkpoint(io::CheckpointWriter &writer, const Eigen::MatrixXd &solution, const io::CheckpointMetadata &metadata) const override;
        void deserialize_checkpoint(const io::CheckpointReader &reader, Eigen::MatrixXd &solution) override;
        std::vector<io::OutputField> output_fields(
            const io::OutputSample &sample,
            const Eigen::MatrixXd &solution,
            const io::OutputFieldOptions &options) const override;
 
    protected:
        void reset() override;
        void load_mesh(const mesh::Mesh &mesh, const json &args) override;
        void build_basis(mesh::Mesh &mesh, 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 build_rhs_assembler() override;
        void solve_problem(
            Eigen::MatrixXd &sol,
            const InitialConditionOverride *initial_condition_override,
            const ForwardStepCallback &post_step) override;
 
    private:
        int mesh_displacement_ndof() const;
        int solid_displacement_ndof() const;
        int fluid_interface_multiplier_ndof() const;
        int mesh_interface_multiplier_ndof() const;
        int total_ndof() const;
        int pressure_offset() const { return primary_ndof(); }
        int mesh_displacement_offset() const { return primary_ndof() + pressure_space_.n_bases; }
        int solid_displacement_offset() const { return mesh_displacement_offset() + mesh_displacement_ndof(); }
        int fluid_interface_multiplier_offset() const { return solid_displacement_offset() + solid_displacement_ndof(); }
        int mesh_interface_multiplier_offset() const { return fluid_interface_multiplier_offset() + fluid_interface_multiplier_ndof(); }
        int average_pressure_offset() const { return mesh_interface_multiplier_offset() + mesh_interface_multiplier_ndof(); }
        json mesh_material_args() const;
        json solid_varform_args() const;
        json time_integrator_args(int fe_space_id) const;
        void build_mesh_displacement_boundary(mesh::Mesh &mesh);
        void build_interface_operators();
        void prepare_fsi_initial_solution(Eigen::MatrixXd &sol) const;
        void build_forms(Eigen::MatrixXd &sol, double t);
        void solve_nonlinear_step(int step, Eigen::MatrixXd &sol);
        void update_transient_form_weights();
        void save_fsi_timestep(double time, int step, const Eigen::MatrixXd &solution) const;
 
        int mesh_displacement_space_id_ = -1;
        int displacement_space_id_ = -1;
        int fluid_geometry_id_ = -1;
        int solid_geometry_id_ = -1;
        bool has_solid_ = false;
        std::string mesh_elastic_formulation_ = "NeoHookean";
        std::string solid_elastic_formulation_ = "NeoHookean";
        json solid_args_;
        std::shared_ptr<NonlinearElasticTransientVarForm> solid_varform_;
        std::vector<std::pair<mesh::Navigation::Index, mesh::Navigation::Index>> interface_2d_;
        std::vector<std::pair<mesh::Navigation3D::Index, mesh::Navigation3D::Index>> interface_3d_;
        FESpace mesh_displacement_space_;
        VarFormBoundaryState mesh_displacement_boundary_;
        std::shared_ptr<assembler::Problem> mesh_displacement_problem_;
        assembler::AssemblyValsCache mesh_displacement_ass_vals_cache_;
        assembler::AssemblyValsCache mesh_displacement_mass_ass_vals_cache_;
        assembler::AssemblyValsCache mesh_displacement_pure_mass_ass_vals_cache_;
        std::shared_ptr<assembler::Assembler> mesh_elastic_assembler_;
        std::shared_ptr<assembler::Mass> mesh_mass_assembler_;
        std::shared_ptr<assembler::HRZMass> mesh_pure_mass_assembler_;
        std::shared_ptr<assembler::RhsAssembler> mesh_rhs_assembler_;
        Eigen::MatrixXd mesh_rhs_;
        Eigen::MatrixXd fluid_zero_rhs_;
        StiffnessMatrix mesh_pure_mass_;
        StiffnessMatrix interface_velocity_trace_;
        StiffnessMatrix interface_solid_velocity_trace_;
        StiffnessMatrix interface_mesh_trace_;
        StiffnessMatrix interface_solid_mesh_trace_;
 
        std::vector<std::shared_ptr<assembler::MultiSpacesNLAssembler>> ale_assemblers_;
        std::shared_ptr<time_integrator::ImplicitTimeIntegrator> mesh_displacement_time_integrator_;
        std::vector<std::shared_ptr<solver::Form>> fsi_forms_;
        std::vector<std::shared_ptr<solver::AugmentedLagrangianForm>> fsi_al_forms_;
        std::shared_ptr<solver::NLProblem> fsi_problem_;
        std::shared_ptr<solver::NavierStokesFSIForm> ale_form_;
        std::shared_ptr<solver::FSIInterfaceForm> interface_form_;
        std::shared_ptr<solver::StackedForm> auxiliary_form_;
        std::shared_ptr<solver::ElasticForm> mesh_elastic_form_;
        std::shared_ptr<solver::BodyForm> fluid_neumann_form_;
        std::shared_ptr<solver::BodyForm> mesh_body_form_;
        std::shared_ptr<solver::NavierStokesFSIAveragePressureForm> average_pressure_form_;
    };
} // namespace polyfem::varform