From 8d115d373795d173acfb98d3115e38c527d7e730 Mon Sep 17 00:00:00 2001
From: "Claudius \"keldu\" Holeksa" <mail@keldu.de>
Date: Mon, 13 Jul 2026 16:46:49 +0200
Subject: Prepare separation into files

---
 modules/core/c++/component/psm.hpp | 83 ++++++++++++++++++++++++++++++++++++++
 1 file changed, 83 insertions(+)
 create mode 100644 modules/core/c++/component/psm.hpp

(limited to 'modules/core/c++/component/psm.hpp')

diff --git a/modules/core/c++/component/psm.hpp b/modules/core/c++/component/psm.hpp
new file mode 100644
index 0000000..cada53c
--- /dev/null
+++ b/modules/core/c++/component/psm.hpp
@@ -0,0 +1,83 @@
+#pragma once
+
+#include "../macroscopic.hpp"
+#include "../equilibrium.hpp"
+#include "common.hpp"
+
+namespace kel {
+namespace lbm {
+namespace cmpt {
+struct PSM {};
+}
+
+/**
+ * PSM collision operator for LBM
+ */
+template<typename T, typename Descriptor, typename Encode>
+class component<T, Descriptor, cmpt::PSM, Encode> {
+private:
+	saw::data<T> relaxation_;
+	saw::data<T> frequency_;
+public:
+	component(
+		typename saw::native_data_type<T>::type relaxation__
+	):
+		relaxation_{relaxation__}
+	{
+		saw::data<T> one;
+		one = 1.0;
+		frequency_ = one / relaxation_;
+	}
+
+	template<typename CellFieldSchema, typename MacroFieldSchema>
+	void apply(const saw::data<CellFieldSchema, Encode>& field, const saw::data<MacroFieldSchema,Encode>& macros, saw::data<sch::FixedArray<sch::UInt64,Descriptor::D>> index, saw::data<sch::UInt64> time_step) const {
+	
+		using dfi = df_info<T,Descriptor>;
+		bool is_even = ((time_step.get() % 2) == 0);
+
+		auto& dfs_old_f = (is_even) ? field.template get<"dfs_old">() : field.template get<"dfs">();
+		auto& porous_f = macros.template get<"porosity">();
+
+		auto& rho_f = macros.template get<"density">();
+		auto& vel_f = macros.template get<"velocity">();
+		
+		saw::data<sch::Scalar<T>>& rho = rho_f.at(index);
+		saw::data<sch::Vector<T,Descriptor::D>>& vel = vel_f.at(index);
+
+		compute_rho_u<T,Descriptor>(dfs_old_f.at(index),rho,vel);
+		
+		auto eq = equilibrium<T,Descriptor>(rho,vel);
+
+		saw::data<T> one{1.0};
+		auto& porous = porous_f.at(index);
+		auto flip_porous = one - porous.at({});
+
+		auto& dfs = dfs_old_f.at(index);
+
+		auto dfs_cpy = dfs;
+
+		for(uint64_t i = 0u; i < Descriptor::Q; ++i){
+			uint64_t i_opp = dfi::opposite_index[i];
+			dfs.at({i}) = dfs_cpy.at({i}) + frequency_ * (eq.at(i) - dfs_cpy.at({i})) * porous.at({}) + (dfs_cpy.at({i_opp}) - dfs_cpy.at({i}) ) * flip_porous;
+		}
+
+		auto& force_f = macros.template get<"force">();
+		auto& force = force_f.at(index);
+		for(uint64_t k{0u}; k < Descriptor::D; ++k){
+			force.at({{k}}).set(0);
+		}
+
+		for(uint64_t i{0u}; i < Descriptor::Q; ++i){
+			uint64_t i_opp = dfi::opposite_index[i];
+			auto dfs_diff = dfs.at({i}) - dfs.at({i_opp});
+			for(uint64_t k{0u}; k < Descriptor::D; ++k){
+				force.at({{k}}) = force.at({{k}}) + dfs_diff * dfi::directions[i][k];
+			}
+		}
+
+		force = force * porous;
+	}
+};
+
+}
+}
-- 
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