Talk:Sherwood number

empirical equation

I think for the empirical equation for the sherwood number as a function of the Reynolds and Schmidt number boundary conditions need to be given. Without a special case to aply the equation to it is useless.

when sh number are going to zero? —Preceding unsigned comment added by 80.66.183.39 (talk) 15:09, 27 October 2009 (UTC)

issue with the article

I am not specialist in Mass Transfer but describing the Sherwood number as the ratio of convective forces to diffusive forces for mass transfer seems wrong to me. It is rather the ratio of the total magnitude of mass transfer to the mass transfer caused by diffusive forces only. Sh informs about the importance of diffusion in the global mass transfer: When Sh is low (approaches 1), diffusion dominates whereas when Sh is high (tends to infinity) other phenomena such as forced convection dominate mass transport. Note that the ratio of convective forces to diffusive forces for mass transfer is the Peclet number.

Hello, I agree that the Péclet number is the convective/diffusive ratio. With the Sherwood number, this uses the fluid diffusivity, and the mass transfer coefficient is that in the fluid, so saying "ratio of diffusion to mass transport" is meaningless.

As with the Nusselt number, the physical meaning of the Sherwood number should be the ratio of the lengscale to the boundary layer thickness. That is because the mass flux is given by the mass transfer coefficient times the difference (fluid bulk concentration minus surface concentration) $h_{D}(C_{bulk}-C_{surf})$. That's roughly equal to the diffusivity divided by concentration boundary layer thickness ${\frac {D}{\delta _{C}}}(C_{bulk}-C_{surf})$.

So ${\rm {Sh}}=h_{D}L/D=L/\delta _{C}$. This is the physical meaning. — Preceding unsigned comment added by Hazelsct (talk • contribs) 22:12, 26 July 2024 (UTC)