From a1682eec9d878bb0e2b9a236737352a5f7765629 Mon Sep 17 00:00:00 2001
From: Allentro <rossallen1996@gmail.com>
Date: Tue, 2 Apr 2024 23:42:15 +0100
Subject: [PATCH 1/2] Resetting export.t and export.data in
 initialise_exports()

---
 festim/hydrogen_transport_problem.py | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/festim/hydrogen_transport_problem.py b/festim/hydrogen_transport_problem.py
index af0efd000..8ab9a92ea 100644
--- a/festim/hydrogen_transport_problem.py
+++ b/festim/hydrogen_transport_problem.py
@@ -232,6 +232,7 @@ def volume_meshtags(self, value):
             raise TypeError(f"value must be of type dolfinx.mesh.MeshTags")
 
     def initialise(self):
+
         self.create_species_from_traps()
         self.define_function_spaces()
         self.define_meshtags_and_measures()
@@ -324,8 +325,9 @@ def define_temperature(self):
     def initialise_exports(self):
         """Defines the export writers of the model, if field is given as
         a string, find species object in self.species"""
-
         for export in self.exports:
+            export.t = []
+            export.data = []
             # if name of species is given then replace with species object
             if isinstance(export.field, list):
                 for idx, field in enumerate(export.field):

From f08f0b5c83d11b511a129316d040b61d0bf4f3b1 Mon Sep 17 00:00:00 2001
From: Allentro <rossallen1996@gmail.com>
Date: Tue, 2 Apr 2024 23:45:04 +0100
Subject: [PATCH 2/2] Adding a test to check export.t and export.data have been
 reset.

---
 test/test_h_transport_problem.py | 29 +++++++++++++++++++++++++++++
 1 file changed, 29 insertions(+)

diff --git a/test/test_h_transport_problem.py b/test/test_h_transport_problem.py
index 36c484f02..340f9caa1 100644
--- a/test/test_h_transport_problem.py
+++ b/test/test_h_transport_problem.py
@@ -337,6 +337,35 @@ def test_initialise_exports_multiple_exports_same_species():
     assert Ds[0].x.array[0] == Ds[1].x.array[0]
 
 
+def test_export_resets_quantities():
+    """Test that the export.data and export.t are correctly reset every time a simulation is initiated."""
+    my_mat = F.Material(D_0=1, E_D=0)
+    H = F.Species("H")
+    surf = F.SurfaceSubdomain1D(id=1, x=4)
+
+    my_export = F.SurfaceFlux(
+        field=H,
+        surface=surf,
+    )
+
+    my_model = F.HydrogenTransportProblem(
+        mesh=F.Mesh1D([0, 1, 2, 3, 4]),
+        subdomains=[F.VolumeSubdomain1D(id=1, borders=[0, 4], material=my_mat), surf],
+        species=[H],
+        temperature=400,
+        exports=[my_export],
+    )
+
+    my_model.settings = F.Settings(atol=1e-15, rtol=1e-15, transient=False)
+
+    for i in range(3):
+        my_model.initialise()
+        my_model.run()
+
+        assert my_model.exports[0].t == [0.0]
+        assert my_model.exports[0].data == [0.0]
+
+
 def test_define_D_global_multispecies():
     """Test that the D_global object is correctly defined when there are multiple
     species in one subdomain"""