An experimental research on surface oscillation of buoyant-thermocapillary convection in open cylindrical annuli

An experiment is carried out on the surface oscillation of buoyant-thermocapillary convection in an open cylindrical annulus. When the radial temperature difference ΔT reaches a critical value ΔT _c, a regular oscillation appears and soon disappears on the open surface, which varies when the liquid layer’s thickness h and temperature difference ΔT are varied. With growth of ΔT, dominant frequency of the visible oscillation will grow too but is found within certain frequencies. Driving forces, buoyance and thermocapillarity, are responsible for this phenomanon and the “balance” point is considered to exist when h is between 4.5–5.0mm. Surface oscillation region is also found restricted within a narrow gap when Bo is smaller than 3.7.