Bagnold number

Named after Ralph Bagnold.

Bagnold number (plural Bagnold numbers)

1. (physics, uncommon) The ratio of grain collision stresses to viscous fluid stresses in a granular flow with interstitial Newtonian fluid: ${\displaystyle \mathrm {Ba} ={\frac {\rho d^{2}\lambda ^{1/2}{\dot {\gamma }}}{\mu }}}$, where ${\displaystyle \rho }$ is the particle density, ${\displaystyle d}$ is the grain diameter, ${\displaystyle {\dot {\gamma }}}$ is the shear rate, ${\displaystyle \mu }$ is the dynamic viscosity of the interstitial fluid and ${\displaystyle \lambda }$ is the linear concentration.

• Bagnold number on Wikipedia.Wikipedia