Merge pull request #1859 from pybamm-team/stress-induced-diffusion-op…

…tion

default stress-induced diffusion

pybamm/models/full_battery_models/base_battery_model.py

@@ -243,9 +243,15 @@ def __init__(self, extra_options):
         # provided
 
         # Change the default for stress-induced diffusion based on which particle
-        # mechanics option is provided
+        # mechanics option is provided. If the user doesn't supply a particle mechanics
+        # option set the default stress-induced diffusion option based on the default
+        # particle mechanics option which may change depending on other options
+        # (e.g. for stress-driven LAM the default mechanics option is "swelling only")
         mechanics_option = extra_options.get("particle mechanics", "none")
-        if mechanics_option == "none":
+        if (
+            mechanics_option == "none"
+            and default_options["particle mechanics"] == "none"
+        ):
             default_options["stress-induced diffusion"] = "false"
         else:
             default_options["stress-induced diffusion"] = "true"

tests/unit/test_models/test_full_battery_models/test_base_battery_model.py

@@ -33,7 +33,7 @@
 'SEI': 'none' (possible: ['none', 'constant', 'reaction limited', 'solvent-diffusion limited', 'electron-migration limited', 'interstitial-diffusion limited', 'ec reaction limited'])
 'SEI film resistance': 'none' (possible: ['none', 'distributed', 'average'])
 'SEI porosity change': 'false' (possible: ['false', 'true'])
-'stress-induced diffusion': 'false' (possible: ['false', 'true'])
+'stress-induced diffusion': 'true' (possible: ['false', 'true'])
 'surface form': 'differential' (possible: ['false', 'differential', 'algebraic'])
 'thermal': 'x-full' (possible: ['isothermal', 'lumped', 'x-lumped', 'x-full'])
 'total interfacial current density as a state': 'false' (possible: ['false', 'true'])
@@ -250,6 +250,10 @@ def test_options(self):
                     )
                 }
             )
+        # check default options change
+        model = pybamm.BaseBatteryModel({"loss of active material": "stress-driven"})
+        self.assertEqual(model.options["particle mechanics"], "swelling only")
+        self.assertEqual(model.options["stress-induced diffusion"], "true")
 
         # crack model
         with self.assertRaisesRegex(pybamm.OptionError, "particle mechanics"):