Hi to all,

Does anybody knows a correlation for the Nusselt number in annular or circular rotating ducts?

Peter

Hi Peter,

Nusselt number is a function of Reynolds,Prandtl,Brinkman nos,& the geometric factor L/D. In the absence of viscous dissipation Brinkman no can be neglected. This is true for constant wall temperature. When the temperature differences are large,then you need to include mu_b/mu_0 in the correlation relation where mu_b is the bulk viscosity and mu_0 is the viscosity at the temperaure of the solid surface. Nu=Nu(Re,Pr,L/D,(mu_b)/(mu_0)). This is for forced convection. If density varies significantly,then some free convection will occur and Grashof no must be taken into account. Try to get hold of some good references to check these things. Hope you have got some idea. If you have access to the library that's the best place to dig out. Regards gita