Stanton number

Remarks

With a length $L$, conductivity $k$, kinematic viscosity $\nu$ and diffusivity $\alpha = k / (\rho c_p)$, one has $\mathrm{St} = \mathrm{Nu} / (\mathrm{Re} \, \mathrm{Pr})$. Check: $\mathrm{Nu} / (\mathrm{Re} \, \mathrm{Pr}) = (h L / k) \cdot \alpha / (U L) = h / (\rho c_p U)$. This uses the Nusselt, Reynolds and Prandtl numbers.

Example: water with $\rho c_p \approx 4.2 \cdot 10^6$ joules per cubic metre per kelvin, at $U = 1$ metre per second, with $h = 4200$ in SI units. Then $\mathrm{St} \approx 4200 / (4.2 \cdot 10^6) = 10^{-3}$.

Non-example: $h L / k$ is not the Stanton number; it is the Nusselt number and does not involve the flow speed.