Add model for computing peclet number (and other dimensionless numbers?)

[jgostick]

Would it be handy to have the Re and Pe, etc. computed for each conduit, then these could be used elsewhere, like in the taylor_aris_diffusion models?

[ma-sadeghi]

One issue: I looked at taylor_aris_diffusion model, and it seems that we calculate "pore" Peclet number based the throat flow rate, which makes sense. But, my point is that each pore will have as many Peclet numbers as the number of connected throats. So, not sure if it's a good candidate to be refactored as a pore-scale model. For throats, though, it can be done no problem.