ComputeCFLDustDrift.hpp

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// -------------------------------------------------------//
//
// SHAMROCK code for hydrodynamics
// Copyright (c) 2021-2026 Timothée David--Cléris <tim.shamrock@proton.me>
// SPDX-License-Identifier: CeCILL Free Software License Agreement v2.1
// Shamrock is licensed under the CeCILL 2.1 License, see LICENSE for more information
//
// -------------------------------------------------------//
 
#pragma once

 
#include "shambackends/kernel_call_distrib.hpp"
#include "shammodels/sph/math/density.hpp"
#include "shamrock/solvergraph/IFieldSpan.hpp"
#include "shamrock/solvergraph/Indexes.hpp"
#include "shamrock/solvergraph/ScalarEdge.hpp"
#include "shamsolvergraph/node/INode.hpp"
#include "shamsys/NodeInstance.hpp"
 
#define NODE_EDGES(X_RO, X_RW)                                                                     \
    X_RO(shamrock::solvergraph::Indexes<u32>, part_counts)                                         \
    X_RO(shamrock::solvergraph::ScalarEdge<Tscal>, C_drift)                                        \
    X_RO(shamrock::solvergraph::ScalarEdge<Tscal>, cfl_density_threshold)                          \
    X_RO(shamrock::solvergraph::ScalarEdge<Tscal>, pmass)                                          \
    X_RO(shamrock::solvergraph::ScalarEdge<Tscal>, hfactd)                                         \
    X_RO(shamrock::solvergraph::IFieldSpan<Tscal>, hpart)                                          \
    X_RO(shamrock::solvergraph::IFieldSpan<Tscal>, s_j)                                            \
    X_RO(shamrock::solvergraph::IFieldSpan<Tvec>, delta_v)                                         \
    X_RW(shamrock::solvergraph::IFieldSpan<Tscal>, cfl_dt)
 
template<class Tvec>
class ComputeCFLDustDrift : public shamrock::solvergraph::INode {
 
    using Tscal = shambase::VecComponent<Tvec>;
 
    u32 nbins;
 
    public:
    ComputeCFLDustDrift(u32 nbins) : nbins(nbins) {}
 
    EXPAND_NODE_EDGES(NODE_EDGES)
 
    inline void _impl_evaluate_internal() {
        auto edges = get_edges();
 
        auto dev_sched = shamsys::instance::get_compute_scheduler_ptr();
 
        Tscal C_drift               = edges.C_drift.value;
        Tscal cfl_density_threshold = edges.cfl_density_threshold.value;
 
        Tscal pmass  = edges.pmass.value;
        Tscal hfactd = edges.hfactd.value;
 
        sham::distributed_data_kernel_call(
            dev_sched,
            sham::DDMultiRef{
                edges.hpart.get_spans(), edges.delta_v.get_spans(), edges.s_j.get_spans()},
            sham::DDMultiRef{edges.cfl_dt.get_spans()},
            edges.part_counts.indexes,
            [C_drift, cfl_density_threshold, pmass, hfactd, nbins = this->nbins](
                u32 id_a,
                const Tscal *hpart,
                const Tvec *delta_v,
                const Tscal *s_j,
                Tscal *cfl_dt) {
                u32 id_a_d = id_a * nbins;
 
                Tscal h_a   = hpart[id_a];
                Tscal rho_a = shamrock::sph::rho_h(pmass, h_a, hfactd);
 
                auto rho_dust = [&](int j) {
                    auto tmp = s_j[id_a_d + j];
                    return tmp * tmp;
                };
 
                auto epsilon_j = [&](Tscal rho_d_j) {
                    return rho_d_j / rho_a;
                };
 
                Tvec eps_dv{};
                for (int j = 0; j < nbins; j++) {
                    Tscal rho_d_j_a = rho_dust(j);
                    eps_dv += epsilon_j(rho_d_j_a) * delta_v[id_a_d + j];
                }
 
                Tscal cfl_tmp = std::numeric_limits<Tscal>::infinity();
 
                for (int j = 0; j < nbins; j++) {
                    Tscal rho_d_j_a = rho_dust(j);
                    if (rho_d_j_a > cfl_density_threshold) {
                        Tvec drift_v_j_a       = delta_v[id_a_d + j] - eps_dv;
                        Tscal drift_v_j_a_norm = sycl::length(drift_v_j_a);
                        if (drift_v_j_a_norm > 0) {
                            cfl_tmp = sycl::min(cfl_tmp, h_a / drift_v_j_a_norm);
                        }
                    }
                }
 
                cfl_tmp *= C_drift;
 
                cfl_dt[id_a] = sycl::min(cfl_dt[id_a], cfl_tmp);
            });
    }
 
    inline virtual std::string _impl_get_label() const { return "ComputeCFLDustDrift"; };
 
    inline virtual std::string _impl_get_tex() const { return "C_{\\rm drift}"; };
};
 
#undef NODE_EDGES