Experimental and Theoretical Studies on Velocity Field ofBuoyancy Convection in KNbO₃ Melt

The Schlieren technique coupling with a differential interference microscope 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 movement of the tiny KNbO₃ crystals (～10μm) and the stream velocities of these tracer crystals were measured. In theoretical analysis, the Navier--Stokes equation was solved as a stable field. The general solution for this system of the differential equation was expressed by an approximate power series of azimuth and radius vector. The expression was substituted in the differential equation; a non-trivial solution was obtained exactly. The velocity distribution in the vertical section was obtained which is in qualitative agreement with the experimental result.