Experimental and theoretical studies on velocity field of buoyancy convection in KNbO3 melt

The Schlieren technique coupling with a differential interference microscop e was applied to visualize the KNbO3\ melt motion in a loop-shaped Pt wire heater. The natural convection in KNbO3 melt was traced by observing the mo vement of the tiny KNbO3 crystals (similar to 10 mum) and the stream veloci ties of these tracer crystals were measured. In theoretical analysis, the N avier-Stokes equation was solved as a stable held. The general solution for this system of the differential equation was expressed by an approximate p ower series of azimuth and radius vector. The expression was substituted in the differential equation; a non-trivial solution was obtained exactly. Th e velocity distribution in the vertical section was obtained which is in qu alitative agreement with the experimental result.