primary domain of a function parameter

[veera-visw]

The code I am writing is based on the basic_dfn model. I am, however, keeping all functions and variables in a single environment to keep it simple for me to modify things since the model is in the testing phase.

The problem I have is that a function parameter (Open circuit voltage) is assigned to negative electrode domain and I am not able to understand where this assignment took place. Consider the variable ("U")

definition:
U = pybamm.FunctionParameter("Positive electrode OCP [V]", inputs)
c_s_p = pybamm.Variable(
"Positive particle concentration [mol.m-3]",
domain="positive particle",
auxiliary_domains={
"secondary": "positive electrode",
},
)
c_surf_p = pybamm.surf(c_s_p)

def open_circuit_potential(c_surf_p):
< expression>
return U

param = pybamm.ParameterValues(
"Positive electrode OCP [V]": open_circuit_potential,
)

No where in this code do I explicitly specify the domain for U since I assumed it will be inherited from its dependent variable (c_surf_p). But the variable seems to be registered in the negative domain.

output:
"Out[17]: FunctionParameter(-0x185365db7a99d101, Positive electrode OCP [V], children=['boundary value(negative particle concentration [mol.m-3])'], domains={'primary': ['negative electrode']})"

Since I am using this variable for positve electrode potential, I am getting a mismatch with other variables when I do a subtraction.

Any ideas on why the variable is registered this way and how I can fix it?

Thanks

[veera-visw]

@agriyakhetarpal sorry to tag, any chance you can help me on this?