fixed bug where lumped elements were not being removed in Simulation.subsection

CHANGELOG.md

@@ -35,6 +35,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Significant speedup for field projection computations.
 - Fix numerical precision issue in `FieldProjectionCartesianMonitor`.
 - Bug where lumped elements in the `Simulation` were being overwritten by the `TerminalComponentModeler`.
+- Bug in `Simulation.subsection` where lumped elements were not being correctly removed.
 
 ## [2.7.2] - 2024-08-07
 

tests/test_components/test_simulation.py

@@ -2407,11 +2407,14 @@ def test_to_gds(tmp_path):
 
 @pytest.mark.parametrize("nz", [13, 1])
 @pytest.mark.parametrize("unstructured", [True, False])
-def test_sim_subsection(unstructured, nz):
+def test_sim_subsection(unstructured, nz, log_capture):
     region = td.Box(size=(0.3, 0.5, 0.7), center=(0.1, 0.05, 0.02))
     region_xy = td.Box(size=(0.3, 0.5, 0), center=(0.1, 0.05, 0.02))
 
     sim_red = SIM_FULL.subsection(region=region)
+    # Ensure that in this first test case the lumped element is safely excluded
+    _ = sim_red.volumetric_structures
+    assert_log_level(log_capture, "WARNING")
     assert sim_red.structures != SIM_FULL.structures
     sim_red = SIM_FULL.subsection(
         region=region,

tests/utils.py

@@ -840,6 +840,11 @@ def make_custom_data(lims, unstructured):
             freqs=[1e14, 2e14],
         ),
     ),
+    lumped_elements=[
+        td.LumpedResistor(
+            center=(2, 2, 0), size=(0.2, 0.2, 0), name="Resistor", resistance=42, voltage_axis=0
+        )
+    ],
     symmetry=(0, 0, 0),
     boundary_spec=td.BoundarySpec(
         x=td.Boundary(plus=td.PML(num_layers=20), minus=td.Absorber(num_layers=100)),

tidy3d/components/simulation.py

@@ -1470,12 +1470,16 @@ def subsection(
         # thus, recreate a box instance
         new_box = Box.from_bounds(*new_bounds)
 
-        # inheritance of structures, sources, monitors, and boundary specs
+        # inheritance of structures, lumped elements, sources, monitors, and boundary specs
         if remove_outside_structures:
             new_structures = [strc for strc in self.structures if new_box.intersects(strc.geometry)]
         else:
             new_structures = self.structures
 
+        new_lumped_elements = [
+            elem for elem in self.lumped_elements if new_box.intersects(elem.to_structure.geometry)
+        ]
+
         if sources is None:
             sources = [src for src in self.sources if new_box.intersects(src)]
 
@@ -1558,6 +1562,7 @@ def subsection(
             sources=sources,
             symmetry=symmetry,
             structures=new_structures,
+            lumped_elements=new_lumped_elements,
             **kwargs,
         )