Defining porosity, tortuosity, and particle size as a function of x

[amirsh213]

Hi,
I saw in one of the issues that people tried to define porosity and particle size as a function of x but I have not seen any instruction on how to do that. I defined the porosity as a function x using [data] and a CSV file but when I plot it after simulation, the interpolation function shifts the porosity profile downward meaning I have a smaller average porosity.
Also, I was wondering how I can define the MacMullin number or tortuosity with a customized function (function of porosity) instead of the Bruggeman equation?
Thanks.

[valentinsulzer]

Can you post the code you ran and the results you got for x-dependent porosity?

For the non-Bruggeman tortuosity, we need to add that as a separate submodel, please open an issue

[amirsh213]

It is just a simple 1C discharge. After changing my parameters to desired values I used the attached porosity profile for the anode via [data]. I plotted both porosity profiles on one plot and it seems that Pybamm interpolation is having a hard time interpolating at both ends and skips the last 2.5 um at both ends although I defined my anode length as 98 um.

parameter_values = pybamm.ParameterValues(chemistry=chemistry)

parameter_values["Initial concentration in negative electrode [mol.m-3]"] = 28000
parameter_values["Initial concentration in positive electrode [mol.m-3]"] = 7000

model = pybamm.lithium_ion.DFN()

solver= pybamm.CasadiSolver(mode="safe")

sim = pybamm.Simulation(model, parameter_values=parameter_values, solver=solver)

sim.solve([0, 3110])
sim.plot(['Negative electrode porosity'])

porosity_profile.csv

[valentinsulzer]

try

def neg_porosity(x):
   return 0.25 * x
Para_0.update({'Negative electrode porosity': neg_porosity})

[RuiheLi]

Works! Thank you very much!

[RuiheLi]

Sorry for the spamming, may I further ask how to defien a porosity distribution that is lower at the negative electrode-seperator interface but higher at the negative electrode-current collector interface? I tried something like

def neg_porosity(x):
   return 0.25 * (1-x)
Para_0.update({'Negative electrode porosity': neg_porosity})

but that doesn't work.

[valentinsulzer]

x is in dimensional units (micro meters)

[RuiheLi]

Thanks for the patience! Paste the successful scirpt here for anyone who may need it:

import pybamm as pb;
exp_RPT_text = [ (  "Discharge at 1C for 10 minutes", ) ] 
Experiment_RPT = pb.Experiment( exp_RPT_text * 1 ) 
Model_0 = pb.lithium_ion.DFN() 
Chemistry=pb.parameter_sets.OKane2022 
Para_0=pb.ParameterValues(chemistry=Chemistry) 
def neg_porosity(x_n):
   return 0.25 * (1-x_n/Para_0["Negative electrode thickness [m]"]) 
Para_0.update({'Negative electrode porosity': neg_porosity})
Sim_0 = pb.Simulation( 
    Model_0, 
    experiment = Experiment_RPT, 
    parameter_values = Para_0, 
    solver = pb.CasadiSolver(),) 
Sol_0 = Sim_0.solve(calc_esoh=False)