# Settling velocity of a particle

Settling is the process by which particulates settle to the bottom of a liquid and form a sediment. Settling velocity ($$v_{p}$$, m/s) describes the rate at which  a particle moves through the liquid either due to gravity or due to centrifugal force.

 $$v_{p}=\frac{2}{9}\frac{\rho_{p}\rho _{f}}{\mu }gR^{2}$$ $$g$$ - gravitational acceleration (m/s2) $$R$$ - radius of the spherical particle $$\rho _{p}$$ - mass density of the particles (kg/m3) $$\rho _{f}$$ - mass density of the fluid (kg/m3) $$\mu$$ - dynamic viscosity The settling velocity increases with higher density difference of the particles to water of the particles, larger size (size times density difference in boyant mass) and lower water viscosity.

## Execution

Settling velocity can be calculated based on the parameters of the medium used for the experimental setup and physical characteristics of the particles.

## Used in

 Consult the NanoFASE Library to see abstracts of these deliverable reports:Deliverable D2.2 Section 3.4.1.2

## Contact

Frank von der Kammer

University of Vienna, Austria

Email: frank.von.der.kammer@univie.ac.at