Bagnold number

Etymology
Named after.

Noun

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