hydraulic_diffusivity: Hydraulic diffusivity.
In abarbour/hydrogeo: Tools for hydrogeology and poroelasticity

Description Usage Arguments Details Value Author(s) See Also Examples

A collection of various functions used to estimate hydraulic diffusivity, or characteristic scales associated with fluid diffusion in porous media.

hydraulic_diffusivity(Transmiss, Storativ)

hydraulic_diffusivity_2(Conductiv, SpecificStorage)

hydraulic_diffusivity_3(Length.m = 1, Time.s = 1)

hydraulic_diffusivity_poro(Permeab, B., Beta, nu_u = NULL, nu = NULL)

diffusivity_length(Diffusiv, Time.s = 1)

diffusivity_time(Diffusiv, Length.m = 1)

`Transmiss`	numeric; the transmissivity, with units [X]
`Storativ`	numeric; the storativity, with units [X]
`Conductiv`	numeric; the hydraulic conductivity, with units [X]
`SpecificStorage`	numeric; the specific storage, with units [X]
`Length.m`	numeric; the length scale, in [m], to calcuate characteristic diffusion time for.
`Time.s`	numeric; the time scale, in [s], to calcuate characteristic diffusion length for.
`Permeab`	numeric; the permeability, with units m^2
`B.`	numeric; Skempton's coefficient B
`Beta`	numeric; the bulk compressibility
`nu_u`	numeric; undrained Poisson's ratio
`nu`	numeric; Poisson's ratio
`Diffusiv`	numeric; the diffusivity, with units m^2/s

Because diffusivity is scale and flow-law dependent, there are many definitions. These include, but are not limited to:

hydraulic_diffusivity: T / S

which uses transmissivity and storativity (careful, this can be problematic); an alternate definition:

hydraulic_diffusivity_2: C / S_s

which uses hydraulic conductivity and specific storage; another alternate defintion:

hydraulic_diffusivity_3: x^2 / 4 π t

which based on a harmonic perturbation of pore fluids in a sphere (Biot's second compressional wave); (note that this definition provides an upper bound on diffusivity;) and yet another definition: