# dot-get_Dx: D_x: Calculate diffusion coefficient for a given temperature... In 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_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
)

```

tealeaves documentation built on July 20, 2022, 5:07 p.m.