Question

Given that Nu = Nusselt number, Re = Reynolds number, Pr = Prandtl number, Sh = Sherwood number, Sc = Schmidt number and Gr = Grashoff number. The number relationship for free convective heat transfer is given as,
1. Nu = f(Gr, Pr)
2. Sh = f(Sc, Gr)
3. Nu = f(Re, Pr)
4. Sh = f(Re, Sc)

Answer 1

Correct Answer - Option 1 : Nu = f(Gr, Pr)

For forced convection

Nu = C Re^m Prⁿ  

For free convection

Nu = C(Gr Pr)^m

Schmidt number (Sc): Ratio of molecular diffusivity of momentum to molecular diffusivity of mass transfer.

\(Sc=\frac{\mu}{\rho D}=\frac{\nu}{ D}\)

Sherwood number (Sh): Ratio of total mass transfer rate to mass transfer by molecular diffusion

\(Sh_L=\frac{h_m L}{D}\)

Sh = f(Re,Sc)