Laminar forced convection heat transfer in eccentric annuli.

Abstract

Numerical computation has been carried out for the laminar forced convective heat transfer in eccentric annuli. The finite difference equivalents of the governing equations of velocity and temperature fields written with a bipolar coordinate system were solved with an iterative procedure. A study has been made for two types of the second kind of thermal boundary conditions. The friction coefficient and average Nusselt number obtained were found to agree with the results previously reported by others. This validates the present computational method. The obtained cross-sectional distributions of velocity and of temperature, and the peripheral distributions of wall temperature and of local Nusselt number were discussed in detail. When the radius ratio is rather close to unity and eccentricity is large, the peripheral distributions of the friction coefficient and the local Nusselt number are remarkably nonuniform in relation to the conspicuous nonuniformity of velocity in the eccentric annulus. The local Nusselt number then takes a negative value in some regions. The wall temperature there is lower than the fluid bulk mean temperature because of a large peripheral nonuniformity of wall temperature. The temperature field in some cases is significantly far from axisymmetry.