Numerical and experimental studies on electomagnetic stirring

Intruduction

We present direct numerical simulations (DNS) of the flow in a finite cylinder driven by a rotating magnetic field. The main idea is that externally applied magnetic field can be used to control the motion of the liquid during the growth of single crystals in a good electrical conductors. The experiments have demonstrated that rotating magnetic field produced much better solid-solution or alloyed crystals and reduce small-scale spatial oscillations of the additive concentration in nearly pure crystal. The subject is complicated by the fact that the Taylor-Görtler instability of the side layer and the instability of the Bödewadt-type horizontal layer occur in the flow depending on the aspect ratio and magnetic Taylor number Employing the rigid-body and low-frequency approximations the mathematical model reduces to the Navier-Stokes equations with a priori known Lorentz force. A second-order finite-element method combined with Adams-Bashforth time integrations is used for discretization.
The transient and early turbulent flow regimes have been investigated in detail by numerical computation. Some characteristic features such as dominating large structures and homogenous rotating core have been identified in flow. Furthermore, weak secondary flow appear near the top and bottom of the walls due to existence of the Bödewadt layers.