Numerical Simulation of a thin liquid film over a heated rotating disc and cone

Abstract

A computational fluid dynamics (CFD) model, based on the volume of fluid (VOF) approach, is used to simulate heat transfer from a rotating disc and cone to a thin water film flowing over it. Simulations are carried out on a 2D-axisymmetric Eulerian mesh for a wide range of Reynolds and Rossby numbers. The temperature of the disc is kept below the saturation temperature for all cases. The prediction shows film thickness exhibits a radial decay at the entry and three distinct zones are identified: inertia, Coriolis, and centrifugal. The magnitude and the location of the peak of the film are a function of the combined effect of the Reynolds number and the Rossby number. Specifically, a reduction of Rossby number from 103 to 0.5 at fixed Reynolds number of 105, reduced the average film thickness by nine times. A further 21 % reduction in film thickness was achieved by increasing the Reynolds number from 105 to 107 at Rossby of 0.5. However, the thinner film thickness under these conditions did not result in improved heat transfer (Tout at Re = 107 is 9 % lower than Re = 105 for TS = 353 K). The higher Reynolds number is detrimental to the heat transfer due to the greater mass flow rate and velocity in the radial direction impacting the heat transfer rate. Further improvement in heat transfer is achieved by greater centrifugal force via reduced cone angle. Overall, optimal heat transfer was reached with a lower (or smaller) cone angle of 60° at a lower Reynolds number of 105 and a lower Rossby number of 0.5.