Numerical investigation of surface disturbance on liquid metal falling film flows in a magnetic field gradient

D. Gao - N. B. Morley

Department of Mechanical and Aerospace Engineering University of California, Los Angeles, CA 90095

Abstract
The surface stability characters of falling film flows on an inclined plane in a spanwise magnetic field with constant streamwise gradient are investigated by the direct numerical simulation of the Navier--Stokes equations and magnetic induction equation based on the Volume of Fluid (VOF) method for free surface tracking. The spatial disturbance, a small rectangular rise or a sinusoidal bump, is imposed on the otherwise fully developed flat MHD film. The free surface behaviors under the disturbances are calculated based on a 2D MHD model for the film flow down an inclined plane. It is found that the surface disturbance is rapidly enhanced in streamwise extent and in amplitude, with the traveling speed of disturbance largely reduced. These MHD surface stability features are discussed and explained in terms of the induced electrical currents and thereby the MHD drag due to the magnetic field gradient. Figs 11, Refs 19.