Renaming velocity to momentum. for now

1 files changed, 409 insertions, 107 deletions

diff --git a/modules/core/c++/psm.hpp b/modules/core/c++/psm.hpp
index 15ad0f8..2daff5e 100644
--- a/modules/core/c++/psm.hpp
+++ b/modules/core/c++/psm.hpp
@@ -55,7 +55,7 @@ public:
 		auto& porous_f = macros.template get<"porosity">();
 
 		auto& rho_f = macros.template get<"density">();
-		auto& vel_f = macros.template get<"velocity">();
+		auto& vel_f = macros.template get<"momentum">();
 		
 		saw::data<sch::Scalar<T>>& rho = rho_f.at(index);
 		saw::data<sch::Vector<T,Descriptor::D>>& vel = vel_f.at(index);
@@ -105,116 +105,418 @@ public:
 	component() = default;
 
 	template<typename CellFieldSchema, typename MacroFieldSchema, typename ParticleSchema>
-	void apply(const saw::data<CellFieldSchema, Encode>& field, const saw::data<MacroFieldSchema,Encode>& macros, const saw::data<ParticleSchema,Encode>& pg, saw::data<sch::FixedArray<sch::UInt64,1u>> index, saw::data<sch::UInt64> time_step, saw::data<sch::UInt64> sub_steps) const {
-	
-		using dfi = df_info<T,Descriptor>;
-		bool is_even = ((time_step.get() % 2) == 0);
-		
-		saw::data<sch::Scalar<T>> one;
-		one.at({}) = 1.0;
+void apply(
+    const saw::data<CellFieldSchema, Encode>& field,
+    const saw::data<MacroFieldSchema, Encode>& macros,
+    const saw::data<ParticleSchema, Encode>& pg,
+    saw::data<sch::FixedArray<sch::UInt64,1u>> index,
+    saw::data<sch::UInt64> time_step,
+    saw::data<sch::UInt64> sub_steps
+) const {
 
-		auto& dfs_old_f = (is_even) ? field.template get<"dfs_old">() : field.template get<"dfs">();
+    using dfi = df_info<T,Descriptor>;
 
-		auto& por_f = macros.template get<"porosity">();
-		auto& rho_f = macros.template get<"density">();
-		auto& vel_f = macros.template get<"velocity">();
-		auto& force_f = macros.template get<"force">();
-	
-		{
-			auto parts = pg.template get<"particles">();
-			auto parts_size = parts.meta().at({0u});
-
-			auto& p_coll = pg.template get<"collision">().at({});
-			auto& p_rad = p_coll.template get<"radius">();
-
-			auto& pi = parts.at(index);
-			auto& pirb = pi.template get<"rigid_body">();
-			saw::data<sch::Vector<T,Descriptor::D>>& pirb_pos = pirb.template get<"position">();
-			auto& pirb_pos_old = pirb.template get<"position_old">();
-				
-			saw::data<sch::Scalar<T>> ts;
-			ts.at({}) = one.at({}) / sub_steps.template cast_to<T>();
-
-			saw::data<sch::FixedArray<sch::UInt64,Descriptor::D>> start;
-			saw::data<sch::FixedArray<sch::UInt64,Descriptor::D>> stop;
-
-			auto eo_aabb = particle_aabb<typename ParticleSchema::ValueType>::calculate(pg,{{0u}},vel_f.meta());
-			if(eo_aabb.is_error()){
-				return;
-			}
-			auto& aabb = eo_aabb.get_value();
+    bool is_even = ((time_step.get() % 2u) == 0u);
 
-			/// Ok, I iterate over the space which covers our particle? So lower bounds to upper bounds
-			start = aabb.template get<"a">();
-			stop = aabb.template get<"b">();
+    /*
+     * ------------------------------------------------------------
+     * Fields
+     * ------------------------------------------------------------
+     */
 
-			saw::data<sch::Vector<T,Descriptor::D>> force_p;
-			for(uint64_t i{0u}; i < Descriptor::D; ++i){
-				force_p.at({{i}}) = 0.0;
-			}
-			auto vel_p_old = (pirb_pos-pirb_pos_old) / ts;
-
-			iterator<Descriptor::D>::apply([&](const auto& index_f) -> void{
-				// ask for the d_k value here.
-				// For every value im iterating over I need sth
-				// std::cout<<"Pos: "<<index.at({0u}).get()<<" "<<index.at({1u}).get()<<std::endl;
-			
-				auto& dfs = dfs_old_f.at(index_f);
-				saw::data<sch::Vector<T,Descriptor::D>> rel_dist = saw::math::vectorize_data(index_f).template cast_to<T>() - pirb_pos;
-				saw::data<sch::Scalar<T>> eps;
-				eps.at({}) = 1.5f;
-				
-				auto& por = por_f.at(index_f);
-				por = particle_porosity<T,Descriptor::D,1u,por::ParticleSpheroid<T>>::calculate(rel_dist,p_rad,eps);
-
-				if(por.at({}).get() >= 1.0f){
-					return;
-				}
-
-				saw::data<sch::Vector<T,Descriptor::D>> momentum;
-				for(uint64_t i{0u}; i < Descriptor::D; ++i){
-					momentum.at({{i}}) = 0.0;
-				}
-
-				for(uint64_t i{0u}; i < Descriptor::Q; ++i){
-					saw::data<sch::Vector<T,Descriptor::D>> e_i;
-					saw::data<sch::FixedArray<sch::UInt64,Descriptor::D>> n_ind_i;
-					for(uint64_t k{0u}; k < Descriptor::D; ++k){
-						e_i.at({{k}}) = (dfi::directions[i])[k];
-						n_ind_i.at({k}) = index_f.at({k}) + (dfi::directions[i])[k];
-					}
-
-					uint64_t i_opp = dfi::opposite_index[i];
-
-					auto u_p_e = saw::math::dot(e_i,vel_p_old);
-
-					saw::data<T> dfs_added = dfs.at({i})*(saw::data<T>{1}-u_p_e.at({})) + dfs_old_f.at(n_ind_i).at({i_opp})*(saw::data<T>{1}+u_p_e.at({}));
-					saw::data<sch::Scalar<T>> dfs_added_v;
-					dfs_added_v.at({}) = dfs_added;
-					auto ei_dfs = e_i * dfs_added_v;
-
-					momentum = momentum + ei_dfs;
-				}
-				// technically needs to adjust for rotation as well
-				
-				auto& force = force_f.at(index_f);
-				auto& rho = rho_f.at(index_f);
-				// To Fluid
-				
-				auto flip_por = one - por;
-				force = momentum * flip_por;
-				// To Particle
-				force_p = force_p - force;
-			},start,stop);
-			
-			auto& pirb_acc = pirb.template get<"acceleration">();
-			pirb_acc = force_p / pg.template get<"total_mass">().at({});
-
-			for(saw::data<sch::UInt64> i{0u}; i < sub_steps; ++i){
-				verlet_step_lambda<T,Descriptor::D>(pi,ts);
-			}
-		}
-	}
+    auto& dfs_old_f =
+        (is_even)
+            ? field.template get<"dfs_old">()
+            : field.template get<"dfs">();
+
+    auto& por_f   = macros.template get<"porosity">();
+    auto& rho_f   = macros.template get<"density">();
+    auto& vel_f   = macros.template get<"momentum">();
+    auto& force_f = macros.template get<"force">();
+
+    saw::data<sch::Scalar<T>> one;
+    one.at({}) = 1.0;
+
+		saw::data<sch::Scalar<T>> half;
+		half.at({}) = 0.5;
+
+    /*
+     * ------------------------------------------------------------
+     * Particle
+     * ------------------------------------------------------------
+     */
+
+    {
+        auto parts = pg.template get<"particles">();
+
+        auto& p_coll =
+            pg.template get<"collision">().at({});
+
+        auto& p_rad =
+            p_coll.template get<"radius">();
+
+        auto& pi = parts.at(index);
+
+        auto& pirb =
+            pi.template get<"rigid_body">();
+
+        saw::data<sch::Vector<T,Descriptor::D>>& pirb_pos =
+            pirb.template get<"position">();
+
+        auto& pirb_pos_old =
+            pirb.template get<"position_old">();
+
+
+        /*
+         * --------------------------------------------------------
+         * Particle timestep
+         * --------------------------------------------------------
+         */
+
+        saw::data<sch::Scalar<T>> ts;
+
+        ts.at({}) =
+            one.at({})
+            / sub_steps.template cast_to<T>();
+
+
+        /*
+         * --------------------------------------------------------
+         * Particle momentum
+         * --------------------------------------------------------
+         */
+
+        auto vel_p_old =
+            (pirb_pos - pirb_pos_old) / ts;
+
+
+        /*
+         * --------------------------------------------------------
+         * Find particle AABB
+         * --------------------------------------------------------
+         */
+
+        auto eo_aabb =
+            particle_aabb<
+                typename ParticleSchema::ValueType
+            >::calculate(
+                pg,
+                {{0u}},
+                vel_f.meta()
+            );
+
+        if(eo_aabb.is_error()){
+            return;
+        }
+
+        auto& aabb = eo_aabb.get_value();
+
+        saw::data<sch::FixedArray<sch::UInt64,Descriptor::D>> start;
+        saw::data<sch::FixedArray<sch::UInt64,Descriptor::D>> stop;
+
+        start = aabb.template get<"a">();
+        stop  = aabb.template get<"b">();
+
+
+        /*
+         * --------------------------------------------------------
+         * Total force acting on particle
+         * --------------------------------------------------------
+         */
+
+        saw::data<sch::Vector<T,Descriptor::D>> force_p;
+
+        for(uint64_t k = 0u; k < Descriptor::D; ++k){
+            force_p.at({{k}}) = 0.0;
+        }
+
+
+        /*
+         * --------------------------------------------------------
+         * Iterate over particle AABB
+         * --------------------------------------------------------
+         */
+
+        iterator<Descriptor::D>::apply(
+            [&](const auto& index_f) -> void {
+
+                /*
+                 * ------------------------------------------------
+                 * Distribution function at current cell
+                 * ------------------------------------------------
+                 */
+
+                auto& dfs =
+                    dfs_old_f.at(index_f);
+
+
+                /*
+                 * ------------------------------------------------
+                 * Particle relative position
+                 * ------------------------------------------------
+                 */
+
+                saw::data<sch::Vector<T,Descriptor::D>> rel_dist =
+                    saw::math::vectorize_data(index_f)
+                    .template cast_to<T>()
+                    - pirb_pos;
+
+
+                /*
+                 * ------------------------------------------------
+                 * PSM particle porosity
+                 * ------------------------------------------------
+                 */
+
+                saw::data<sch::Scalar<T>> eps;
+                eps.at({}) = 1.5;
+
+                auto& por =
+                    por_f.at(index_f);
+
+                por =
+                    particle_porosity<
+                        T,
+                        Descriptor::D,
+                        1u,
+                        por::ParticleSpheroid<T>
+                    >::calculate(
+                        rel_dist,
+                        p_rad,
+                        eps
+                    );
+
+
+                /*
+                 * Outside particle.
+                 */
+
+                if(por.at({}).get() >= 1.0){
+                    return;
+                }
+
+
+                /*
+                 * ------------------------------------------------
+                 * Momentum exchange for this cell
+                 * ------------------------------------------------
+                 */
+
+                saw::data<sch::Vector<T,Descriptor::D>> momentum;
+
+                for(uint64_t k = 0u; k < Descriptor::D; ++k){
+                    momentum.at({{k}}) = 0.0;
+                }
+
+
+                /*
+                 * ------------------------------------------------
+                 * D3Q27 / general Q momentum exchange
+                 *
+                 * We exclude i=0 because the rest population has
+                 * no momentum.
+                 *
+                 * The original code summed both directions of
+                 * every opposite pair. Therefore we apply 1/2
+                 * after the sum.
+                 * ------------------------------------------------
+                 */
+
+                for(uint64_t i = 1u; i < Descriptor::Q; ++i){
+
+                    uint64_t i_opp =
+                        dfi::opposite_index[i];
+
+
+                    /*
+                     * Direction vector e_i.
+                     */
+
+                    saw::data<sch::Vector<T,Descriptor::D>> e_i;
+
+                    saw::data<
+                        sch::FixedArray<
+                            sch::UInt64,
+                            Descriptor::D
+                        >
+                    > n_ind_i;
+
+
+                    for(uint64_t k = 0u;
+                        k < Descriptor::D;
+                        ++k){
+
+                        e_i.at({{k}}) =
+                            dfi::directions[i][k];
+
+                        /*
+                         * Neighbor in direction e_i.
+                         */
+
+                        n_ind_i.at({k}) =
+                            index_f.at({k})
+                            + dfi::directions[i][k];
+                    }
+
+
+                    /*
+                     * ------------------------------------------------
+                     * Particle momentum projected onto e_i
+                     * ------------------------------------------------
+                     */
+
+                    auto u_p_e =
+                        saw::math::dot(
+                            e_i,
+                            vel_p_old
+                        );
+
+
+                    /*
+                     * ------------------------------------------------
+                     * Momentum-exchange population
+                     *
+                     * f_i(x)
+                     *
+                     * + f_-i(x + e_i)
+                     *
+                     * with moving-wall correction.
+                     * ------------------------------------------------
+                     */
+
+                    saw::data<T> dfs_added =
+                          dfs.at({i})
+                            * (
+                                saw::data<T>{1.0}
+                                - u_p_e.at({})
+                            )
+
+                        + dfs_old_f
+                            .at(n_ind_i)
+                            .at({i_opp})
+                            * (
+                                saw::data<T>{1.0}
+                                + u_p_e.at({})
+                            );
+
+
+                    /*
+                     * Convert scalar into vector multiplication.
+                     */
+
+                    saw::data<sch::Scalar<T>> dfs_added_v;
+
+                    dfs_added_v.at({}) =
+                        dfs_added;
+
+
+                    /*
+                     * ------------------------------------------------
+                     * Delta p_i
+                     *
+                     * ------------------------------------------------
+                     */
+
+                    momentum =
+                        momentum
+                        + e_i * dfs_added_v;
+                }
+
+
+                /*
+                 * ------------------------------------------------
+                 * Since both i and i_opp were included above,
+                 * compensate for double counting.
+                 *
+                 * This is the important change from your original
+                 * implementation.
+                 * ------------------------------------------------
+                 */
+
+
+
+                momentum =
+                    momentum * half;
+
+
+                /*
+                 * ------------------------------------------------
+                 * PSM solid fraction
+                 *
+                 * por = 1   -> fluid
+                 * por = 0   -> particle
+                 *
+                 * Therefore:
+                 *
+                 * flip_por = 1 - por
+                 * ------------------------------------------------
+                 */
+
+                auto flip_por =
+                    one - por;
+
+
+                /*
+                 * ------------------------------------------------
+                 * Force transferred TO FLUID
+                 * ------------------------------------------------
+                 */
+
+                auto& force =
+                    force_f.at(index_f);
+
+                force =
+                    momentum * flip_por;
+
+
+                /*
+                 * ------------------------------------------------
+                 * Force transferred TO PARTICLE
+                 *
+                 * Newton's third law.
+                 * ------------------------------------------------
+                 */
+
+                force_p =
+                    force_p - force;
+
+            },
+            start,
+            stop
+        );
+
+
+        /*
+         * ------------------------------------------------------------
+         * Particle acceleration
+         * ------------------------------------------------------------
+         */
+
+        auto& pirb_acc =
+            pirb.template get<"acceleration">();
+
+        pirb_acc =
+            force_p
+            / pg.template get<"total_mass">().at({});
+
+
+        /*
+         * ------------------------------------------------------------
+         * Integrate particle
+         * ------------------------------------------------------------
+         */
+
+        for(saw::data<sch::UInt64> i{0u};
+            i < sub_steps;
+            ++i){
+
+            verlet_step_lambda<T,Descriptor::D>(
+                pi,
+                ts
+            );
+        }
+    }
+}
 };
 
 }