From 573bfdc0bbffdb1d68259bc348e36d57471d56be Mon Sep 17 00:00:00 2001
From: "Claudius \"keldu\" Holeksa" <mail@keldu.de>
Date: Tue, 24 Jun 2025 16:49:31 +0200
Subject: Broken cavity2d. why?

---
 c++/collision.hpp         | 10 +++++-----
 examples/cavity_2d.cpp    | 22 +++++++++++++++++-----
 examples/poiseulle_2d.cpp |  4 ----
 3 files changed, 22 insertions(+), 14 deletions(-)

diff --git a/c++/collision.hpp b/c++/collision.hpp
index 7ca7c9f..128a499 100644
--- a/c++/collision.hpp
+++ b/c++/collision.hpp
@@ -40,18 +40,18 @@ public:
 	template<typename CellFieldSchema>
 	void apply(saw::data<CellFieldSchema>& field, saw::data<sch::FixedArray<sch::UInt64,Descriptor::D>> index, uint64_t time_step){
 		bool is_even = ((time_step % 2) == 0);
-		auto& cell = field.at(index);
+		auto& cell = field(index);
 
 		auto& dfs_old = is_even ? cell.template get<"dfs_old">() : cell.template get<"dfs">();
 		auto& dfs = (!is_even) ? cell.template get<"dfs_old">() : cell.template get<"dfs">();
 
-		typename saw::native_data_type<T>::type rho;
-		std::array<typename saw::native_data_type<T>::type, Descriptor::D> vel;
+		saw::data<T> rho;
+		saw::data<sch::FixedArray<T,Descriptor::D>> vel;
 		compute_rho_u<T,Descriptor>(dfs,rho,vel);
-		auto eq = equilibrium<Descriptor>(rho,vel);
+		auto eq = equilibrium<T,Descriptor>(rho,vel);
 
 		for(uint64_t i = 0u; i < Descriptor::Q; ++i){
-			dfs({i}).set(dfs({i}).get() + (1.0 / relaxation_) * (eq[i] - dfs({i}).get()));
+			dfs({i}).set(dfs({i}).get() + (1.0 / relaxation_) * (eq.at(i).get() - dfs({i}).get()));
 		}
 	}
 
diff --git a/examples/cavity_2d.cpp b/examples/cavity_2d.cpp
index 5683d85..bb6c6d8 100644
--- a/examples/cavity_2d.cpp
+++ b/examples/cavity_2d.cpp
@@ -237,7 +237,8 @@ void set_initial_conditions(saw::data<kel::lbm::sch::CavityFieldD2Q9>& latt){
 
 void lbm_step(
 	saw::data<kel::lbm::sch::CavityFieldD2Q9>& latt,
-	bool even_step
+	bool even_step,
+	uint64_t time_step
 ){
 	using namespace kel::lbm;
   using dfi = df_info<sch::T,sch::D2Q9>;
@@ -251,6 +252,20 @@ void lbm_step(
 	component<sch::T, sch::D2Q9, cmpt::MovingWall> bb_lid;
 	bb_lid.lid_vel = {0.1,0.0};
 
+	auto dim = latt.meta();
+
+	for(saw::data<sch::UInt64> i{0u}; i < dim.at(0u); ++i){
+		for(saw::data<sch::UInt64> j{0u}; j < dim.at(1u); ++j ){
+			auto& cell = latt({{i,j}});
+			auto& info = cell.template get<"info">();
+
+			switch(info({0u}).get()){
+				case 1u: {
+					coll.apply(latt, {{i,j}}, time_step);
+				} break;
+			}
+		}
+	}
 	// Collide
 	apply_for_cells([&](auto& cell, std::size_t i, std::size_t j){
 		auto& df = even_step ? cell.template get<"dfs_old">() : cell.template get<"dfs">();
@@ -258,9 +273,6 @@ void lbm_step(
 
 		auto info_val = info({0u}).get();
 		switch(info_val){
-		case 1u:
-			coll.apply(df);
-			break;
 		case 2u:
 			// bb.apply(df);
 			bb_lid.apply(df);
@@ -460,7 +472,7 @@ int main(){
 			++file_no;
 		}
 		
-		lbm_step(lattice, even_step);
+		lbm_step(lattice, even_step, step);
 
 		even_step = not even_step;
 	}
diff --git a/examples/poiseulle_2d.cpp b/examples/poiseulle_2d.cpp
index 4ecf500..f5a7981 100644
--- a/examples/poiseulle_2d.cpp
+++ b/examples/poiseulle_2d.cpp
@@ -72,13 +72,9 @@ int main(int argc, char** argv){
 
 	print_lbm_meta<sch::Float64,sch::Descriptor<2,9>>(conv, {conf.template get<"kinematic_viscosity">()});
 
-
 	saw::data<sch::FixedArray<sch::UInt64,sch::D2Q9::D>> dim{{128, 128}};
 
 	saw::data<sch::CavityFieldD2Q9, saw::encode::Native> lattice{dim};
 
-
-
-
 	return 0;
 }
-- 
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