## Schmidt number $\mathrm{Sc}=\frac{\nu}{D}=\frac{\mu}{\rho D}=\frac{\textrm{momentum diffusion rate}}{\textrm{mass diffusion rate}}$ $\rm Sc$ is the ratio of momentum diffusion rate (or say, viscous diffusion rate, represented by kinematic viscosity) and mass diffusion rate (molecular diffusion rate, $D$). Here $\rho$ is density, $u$ is velocity, $\nu$ is [kinematic viscosity](https://en.wikipedia.org/wiki/Kinematic_viscosity), $\mu$ is [dynamic viscosity](https://en.wikipedia.org/wiki/Dynamic_viscosity), $\nu = \frac{\mu}{\rho}$, $D$ is mass diffusivity. Similarly concepts are [[Prandtl number]] and [[Lewis number]]. >[!Info] >See more on wiki: https://en.wikipedia.org/wiki/Schmidt_number.