Ill-conditioned matrix when using StokesFlow

[kizzle4shaw]

I tried to run Stokes flow simulation on an extracted network from Ketton carbonate but I'm encountering an error below. I need assistance in understanding why is this happening.

[ma-sadeghi]

Hi. Please share a MWE (minimum working example) as it's impossible to debug without.

[kizzle4shaw]

Sorry for the late reply our time difference is quite huge.

Here is the code is used:

import imageio
import numpy as np
import porespy as ps
import openpnm as op
import matplotlib.pyplot as plt
ps.visualization.set_mpl_style()
np.random.seed(10)
im = imageio.volread("C:\\Users\\ERIC\\Desktop\\Ketton\\Ketton.tif")
output = ps.networks.snow2(im, phase_alias = None, boundary_width = 3, accuracy = 'standard', voxel_size = 3.00006e-6, sigma=0.4, r_max = 4, peaks = None)
pn = op.io.network_from_porespy(output.network)
pn['pore.diameter'] = pn['pore.inscribed_diameter']
pn['throat.diameter'] = pn['throat.inscribed_diameter']

pn.add_model(propname='throat.hydraulic_size_factors', model = op.models.geometry.hydraulic_size_factors.pyramids_and_cuboids)
pn.add_model(propname='throat.diffusive_size_factors', model = op.models.geometry.diffusive_size_factors.pyramids_and_cuboids)

h = op.utils.check_network_health(pn)

op.topotools.trim(network=pn, pores=h['disconnected_pores'])
op.topotools.trim(network=pn, pores=h['duplicate_throats'])
op.topotools.trim(network=pn, pores=h['isolated_pores'])

phase = op.phase.Phase(network = pn)
phase['pore.viscosity']=1.0
phase.add_model_collection(op.models.collections.physics.basic)
phase.regenerate_models()

inlet = pn.pores('xmin')
outlet = pn.pores('xmax')

flow = op.algorithms.StokesFlow(network=pn, phase=phase)
flow.set_value_BC(pores=inlet, values=1)
flow.set_value_BC(pores=outlet, values=0)
flow.run()

the aim was to calculate permeability. this network has been extracted from ketton carbonate using snow2.

I also have another problem on top of that, in the hydraulic size factors I tried spheres and cylinders initially but I got an error implying that I have throats bigger than the pores. so i changed to pyramids and cuboids sorry to ask on this issue too.🙂

[ma-sadeghi]

No worries, could you also share the "Ketton.tif"?

[kizzle4shaw]

I downloaded the image here https://imperialcollegelondon.box.com/v/iccpsim-ketton2015. it's more than 200mb I don't think it can be uploaded here.