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je-santos / MPLBM-UT

Library for performing multiphase simulations (based on the Shan-Chen model) in complicated geometries (i.e. porous media 3D images)
GNU General Public License v3.0
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unit conversion for physical values #66

Closed jh-chung1 closed 2 years ago

jh-chung1 commented 2 years ago

Hello, Thank you for this excellent work!

I would like to ask two questions regarding the unit conversion for physical values in single-phase flow.

1) What is the characteristic velocity_physical(U_physical)? I think we need a 1) dx and 2) characteristic velocity_physical to compute dt using this equation follows; X_physical = X_LBM dx t_physical = U_LBM/U_physical dx

But I cannot find information regarding the U_physical. Could you please let me know what it is? or where I can find it?

2) If I use a digitized rock image(64^3 voxel) with a resolution of 2.25 micrometer, then does it mean dx = 2.25 micrometer? or is there rescaling inside? I checked there is scale_2 inside. Then I would like to ask whether it also effects on dx or not.

Thank you again for your great work. I would appreciate it a lot if you could give some explanations about my questions.

jh-chung1 commented 2 years ago

Could you please give me a general introduction for unit conversion to obtain physical value in your code?

je-santos commented 2 years ago

Hi @sci-study-storage

The "physical" velocity depends on the system that you are trying to simulate. You can calculate it using the Reynolds number of your system of interest.