Thermal Flow in a Rotating Spherical Gap With a Dielectrophoretic Central Force Field

Abstract

The understanding of thermal convection in spherical gaps under a central force field is important for large scale geophysical motions. Neglecting the magnetic field, the dielectrophoretic force can be used to produce a central force field under microgravity conditions. In a space experiment, currently under construction, thermal convection in a rotating spherical gap with heated inner sphere and cooled outer sphere will be visualized by a Wollaston interferometer. High voltage is used to produce a dielectrophoretic central force field in the gap. The parameters are chosen in analogy to the convection in the earth’s inner core. The experiment and its restrictions are presented as well as numerical predictions for the expected flows. The axial-symmetric flow is calculated on a staggered grid with a finite-volume method. The conjugate-gradient method with a preconditioner accelerates the approximation. In azimuthal direction a spectral analysis allows a three-dimensional simulation for spherical shells with a wide gap.