dot-get_Dx: D_x: Calculate diffusion coefficient for a given temperature...
In muir-lab/tleavesMC: Schymanski Equation

Description Usage Arguments Details Value References Examples

D_x: Calculate diffusion coefficient for a given temperature and pressure

1	.get_Dx(D_0, Temp, eT, P, unitless)

`D_0`	Diffusion coefficient at 273.15 K (0 °C) and 101.3246 kPa
`Temp`	Temperature in Kelvin
`eT`	Exponent for temperature dependence of diffusion
`P`	Atmospheric pressure in kPa
`unitless`	Logical. Should function use parameters with `units`? The function is faster when FALSE, but input must be in correct units or else results will be incorrect without any warning.

D = D_0 [(T / 273.15) ^ eT] (101.3246 / P)

According to Montieth & Unger (2013), eT is generally between 1.5 and 2. Their data in Appendix 3 indicate eT = 1.75 is reasonable for environmental physics.

Value in m^2/s of class units

Monteith JL, Unsworth MH. 2013. Principles of Environmental Physics. 4th edition. Academic Press, London.

tealeaves:::.get_Dx(
  D_0 = set_units(2.12e-05, m^2/s),
  Temp = set_units(298.15, K),
  eT = set_units(1.75),
  P = set_units(101.3246, kPa),
  unitless = FALSE
)