diff --git a/extern/amrex b/extern/amrex
index 74127d6d8..6d9c25b98 160000
--- a/extern/amrex
+++ b/extern/amrex
@@ -1 +1 @@
-Subproject commit 74127d6d8fa83f922069a25e7ef9f153aa73f68c
+Subproject commit 6d9c25b989f19eaccbc561db8f2e3affe587bff7
diff --git a/src/problems/RadTube/test_radiation_tube.cpp b/src/problems/RadTube/test_radiation_tube.cpp
index a17fb0a01..1d2079e56 100644
--- a/src/problems/RadTube/test_radiation_tube.cpp
+++ b/src/problems/RadTube/test_radiation_tube.cpp
@@ -86,17 +86,12 @@ RadSystem<TubeProblem>::DefineOpacityExponentsAndLowerValues(amrex::GpuArray<dou
 	return exponents_and_values;
 }
 
-// declare global variables
-// initial conditions read from file
-amrex::Gpu::HostVector<double> x_arr;
-amrex::Gpu::HostVector<double> rho_arr;
-amrex::Gpu::HostVector<double> Pgas_arr;
-amrex::Gpu::HostVector<double> Erad_arr;
-
-amrex::Gpu::DeviceVector<double> x_arr_g;
-amrex::Gpu::DeviceVector<double> rho_arr_g;
-amrex::Gpu::DeviceVector<double> Pgas_arr_g;
-amrex::Gpu::DeviceVector<double> Erad_arr_g;
+template <> struct SimulationData<TubeProblem> {
+	amrex::Gpu::DeviceVector<double> x_arr_g;
+	amrex::Gpu::DeviceVector<double> rho_arr_g;
+	amrex::Gpu::DeviceVector<double> Pgas_arr_g;
+	amrex::Gpu::DeviceVector<double> Erad_arr_g;
+};
 
 template <> void QuokkaSimulation<TubeProblem>::preCalculateInitialConditions()
 {
@@ -107,6 +102,11 @@ template <> void QuokkaSimulation<TubeProblem>::preCalculateInitialConditions()
 	std::string header;
 	std::getline(fstream, header);
 
+	std::vector<double> x_arr;
+	std::vector<double> rho_arr;
+	std::vector<double> Pgas_arr;
+	std::vector<double> Erad_arr;
+
 	for (std::string line; std::getline(fstream, line);) {
 		std::istringstream iss(line);
 		std::vector<double> values;
@@ -124,16 +124,16 @@ template <> void QuokkaSimulation<TubeProblem>::preCalculateInitialConditions()
 		Erad_arr.push_back(Erad);
 	}
 
-	x_arr_g.resize(x_arr.size());
-	rho_arr_g.resize(rho_arr.size());
-	Pgas_arr_g.resize(Pgas_arr.size());
-	Erad_arr_g.resize(Erad_arr.size());
+	userData_.x_arr_g.resize(x_arr.size());
+	userData_.rho_arr_g.resize(rho_arr.size());
+	userData_.Pgas_arr_g.resize(Pgas_arr.size());
+	userData_.Erad_arr_g.resize(Erad_arr.size());
 
 	// copy to device
-	amrex::Gpu::copyAsync(amrex::Gpu::hostToDevice, x_arr.begin(), x_arr.end(), x_arr_g.begin());
-	amrex::Gpu::copyAsync(amrex::Gpu::hostToDevice, rho_arr.begin(), rho_arr.end(), rho_arr_g.begin());
-	amrex::Gpu::copyAsync(amrex::Gpu::hostToDevice, Pgas_arr.begin(), Pgas_arr.end(), Pgas_arr_g.begin());
-	amrex::Gpu::copyAsync(amrex::Gpu::hostToDevice, Erad_arr.begin(), Erad_arr.end(), Erad_arr_g.begin());
+	amrex::Gpu::copyAsync(amrex::Gpu::hostToDevice, x_arr.begin(), x_arr.end(), userData_.x_arr_g.begin());
+	amrex::Gpu::copyAsync(amrex::Gpu::hostToDevice, rho_arr.begin(), rho_arr.end(), userData_.rho_arr_g.begin());
+	amrex::Gpu::copyAsync(amrex::Gpu::hostToDevice, Pgas_arr.begin(), Pgas_arr.end(), userData_.Pgas_arr_g.begin());
+	amrex::Gpu::copyAsync(amrex::Gpu::hostToDevice, Erad_arr.begin(), Erad_arr.end(), userData_.Erad_arr_g.begin());
 	amrex::Gpu::streamSynchronizeAll();
 }
 
@@ -145,11 +145,11 @@ template <> void QuokkaSimulation<TubeProblem>::setInitialConditionsOnGrid(quokk
 	const amrex::Box &indexRange = grid_elem.indexRange_;
 	const amrex::Array4<double> &state_cc = grid_elem.array_;
 
-	auto const &x_ptr = x_arr_g.dataPtr();
-	auto const &rho_ptr = rho_arr_g.dataPtr();
-	auto const &Pgas_ptr = Pgas_arr_g.dataPtr();
-	auto const &Erad_ptr = Erad_arr_g.dataPtr();
-	int x_size = static_cast<int>(x_arr_g.size());
+	auto const &x_ptr = userData_.x_arr_g.dataPtr();
+	auto const &rho_ptr = userData_.rho_arr_g.dataPtr();
+	auto const &Pgas_ptr = userData_.Pgas_arr_g.dataPtr();
+	auto const &Erad_ptr = userData_.Erad_arr_g.dataPtr();
+	int x_size = static_cast<int>(userData_.x_arr_g.size());
 
 	const auto radBoundaries_g = RadSystem_Traits<TubeProblem>::radBoundaries;