environmentaltools.processes.fall_velocity

environmentaltools.processes.fall_velocity(d, T, S)

Estimate sediment particle fall velocity using Soulsby’s (1997) formula.

Calculates settling velocity accounting for water temperature and salinity effects on density and viscosity.

Parameters:

• d (float or np.ndarray) – Grain diameter (mm)

• T (float) – Water temperature (°C)

• S (float) – Salinity (ppt or ‰)

Returns:

w – Fall velocity (m/s)

Return type:

float or np.ndarray

Notes

Uses Soulsby (1997) optimization:

w = ν/d * [sqrt(10.36² + 1.049 * D³) - 10.36]

where: - ν is kinematic viscosity (m²/s) - D = [(g(s-1)/ν²)]^(1/3) * d is dimensionless grain size - s = ρₛ/ρ is specific gravity

Valid for natural sediments across wide size range (0.1 μm to 10 mm). Accounts for temperature/salinity effects through density and viscosity.

References

Soulsby, R. (1997). Dynamics of marine sands. Thomas Telford.