Error with permeability coefficient value

[Maria-dot916]

Hi, I'm new to openPNM and I'm running a script similar to https://openpnm.org/examples/applications/effective_diffusivity_and_tortuosity.html using data from an XCT scan. My input binary image is a cropped XCT 300x300x300 px image. The voxel size is 17.99 µm.

network_extraction (Sample1).ipynb

I have attached my script. My sample is fully saturated soil. I've defined voxel size in meters. My nd flow rate was fd rate is [0.00149891]. But then the permeability coefficient was 19729168.03892322 Darcy (!) Is there any obvious mistake in my script for getting such a wrong value?

Thank you

[jgostick]

Can you provide your notebook as a pdf? Github is not rendering it, only letting me download it.

[jgostick]

I should also add that the usual cause of this is not specifying the voxel_size when doing the network extraction, so all the sizes in the extracted network are enormous.

[Maria-dot916]

network_extraction.html
I hope you can open this - I couldn't save it as pdf, it gave me an error.

Thank you

[jgostick]

I am staring at this and cannot find a problem. Can you sent your network as a csv? (op.io.network_to_csv(pn))

[Maria-dot916]

net.csv
Hello, apologies for the late reply, here is the csv file.

[jgostick]

I have looked at your data, and I don't think there is anything wrong with the script/code. I think the problem is that your image and resultant network is too small. I see a pore in the middle of the domain, and there are also 3 very large pores, 2 of which have relatively high coordination numbers of 15. I think these pores are providing a free ride across the domain making K appear unreasonably large. Sorry I can't be more helpful than that.

[jgostick]

I am going to convert this into a discussion since I don't believe there is a bug here.

[Maria-dot916]

Thank you very much jgostick, that was helpful. I'll try again with another larger domain.