No flow at inlet (permeability)

[nltthinh]

Hi, the previous "throat.shape_factor" was solved (for now) by choosing a different model for hydraulic conductance.
But there seems to be no flow (Q = 0) at the inlet. I don't really know where the issue lies.

import porespy as ps 
import openpnm as op
import matplotlib.pyplot as plt
import numpy as np
ps.visualization.set_mpl_style()
np.random.seed(10)

im = ps.generators.blobs(shape=[400,400],porosity=0.6, blobiness=2)
print(ps.metrics.porosity(im))
snow_output = ps.networks.snow2(im, voxel_size=1)

settings = {'pore_shape': 'pyramid',
            'throat_shape': 'cuboid',
            'pore_diameter': 'equivalent_diameter',
            'throat_diameter': 'inscribed_diameter'}
pn, geo = op.io.PoreSpy.import_data(snow_output.network, settings=settings)
pn = ps.networks.label_boundaries(pn, labels=[['left', 'right'], ['front', 'back'], ['top', 'bottom']])

geo.add_model(propname='pore.seed',
              model=op.models.geometry.pore_size.random,
              seed=0)
geo.add_model(propname='pore.diameter',
              model=op.models.geometry.pore_size.weibull,
              scale=0.5e-4, shape=1.5, loc=1e-6)
geo.add_model(propname='pore.volume',
              model=op.models.geometry.pore_volume.sphere)
geo.add_model(propname='throat.diameter',
              model=op.models.geometry.throat_size.from_neighbor_pores,
              mode='min')
geo.add_model(propname='throat.length',
              model=op.models.geometry.throat_length.classic)
geo.add_model(propname='throat.volume',
              model=op.models.geometry.throat_volume.cylinder)

water = op.phases.Water(network=pn)
water['pore.temperature'] = 298
water.add_model(propname='pore.viscosity',
                model=op.models.phases.viscosity.water)
phys = op.physics.GenericPhysics(network=pn, phase=water, geometry=geo)
mod = op.models.physics.hydraulic_conductance.classic_hagen_poiseuille
phys.add_model(propname='throat.hydraulic_conductance', 
               model=mod)

flow = op.algorithms.StokesFlow(network=pn, phase=water)
flow.set_value_BC(pores=pn.pores('top'), values=10000)
flow.set_value_BC(pores=pn.pores('bottom'), values=0)
flow.run()

Q = flow.rate(pores=pn.pores('top'))
A = 400**2
L = 400
mu = 0.001
dP = 1
K = Q*mu*L/A/dP
print('Permeability is ', K)

[jgostick]

Very sorry for the slow reply. Thanks for posting your whole script...made it quite easy to debug:

You have generated a 2D image, then used "top" and "bottom" for the BCs', which means you've put BCs in ALL the pores. If you switch to "left" and "right" you'll get a sensible result. I figured this out by printing flow and got:

――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――
openpnm.algorithms.StokesFlow : alg_01
――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――
#     Properties                                    Valid Values
――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――
1     pore.bc_rate                                      0 / 259  
2     pore.bc_value                                   259 / 259  
3     pore.initial_guess                              259 / 259  
4     pore.pressure                                   259 / 259  
――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――
#     Labels                                        Assigned Locations
――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――
1     pore.all                                      259       
2     throat.all                                    283       
――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――

Where I noticed that you had value BCs in all 259 pores.

[nltthinh]

Hi,

I tried changing

flow.set_value_BC(pores=pn.pores('top'), values=10000)
flow.set_value_BC(pores=pn.pores('bottom'), values=0)

to

flow.set_value_BC(pores=pn.pores('left'), values=10000)
flow.set_value_BC(pores=pn.pores('right'), values=0)

but it doesn't work. The same with front and back. I wonder what difference is there between top, bottom and left, right? Are top and bottom defined as faces facing the screen, while front and back are those on top and bottom?