Effect of the capillary meniscus height on the instability of large Prandtl number Czochralski melt flow

•Experiments on capillary meniscus effect on instability of Czochralski flow.•Measurements by two independent and fully non-intrusive techniques.•Simple empirical relations for critical Grashof number and critical frequency.

Effect of the capillary meniscus on the instability of large Prandtl number Czochralski melt flow is studied experimentally. The measurements are conducted in two experimental facilities by two independent non-intrusive optical techniques. The quantitative results are presented as dependencies of the critical Grashof number (critical temperature difference) on the meniscus height for different Prandtl numbers, radii and aspect ratios. The results show that with increase of the meniscus height the critical temperature difference noticeably grows and sometimes doubles. Recently reported parametric relations for the critical Grashof number and oscillations frequency are extended to include parameters of the meniscus.