# dot-get_Dx: D_x: Calculate diffusion coefficient for a given temperature... In cdmuir/tealeaves: Solve for Leaf Temperature Using Energy Balance

 .get_Dx R Documentation

## D_x: Calculate diffusion coefficient for a given temperature and pressure

### Description

D_x: Calculate diffusion coefficient for a given temperature and pressure

### Usage

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

### Arguments

 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.

### Details

D = D_\mathrm{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

Value in m^2/s of class units

### References

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

### Examples

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
)

cdmuir/tealeaves documentation built on Feb. 28, 2024, 8:21 a.m.