On experimental and numerical prediction of instabilities in Czochralski melt flow configuration

Experimental Modelling of Czochralski Melt Flow with a Slow Crystal Dummy Rotation

“…At zero Reynolds number, i.e., when the crystal dummy is stationary, the critical Grashof numbers and oscillation frequencies are about an order of magnitude larger than those observed for the slow rotation (20 < Re < 50). This agrees with our earlier numerical predictions [5,10]. In agreement with these computations, a slow rotation destabilizes the convective ow starting from a certain small value of the Reynolds number.…”

“…The temperature oscillations appear with a certain frequency and its harmonics, whose values are obtained via the Fourier transform of the temperature histories measured by thermocouples, or by oscillations of the amount of black pixels in a control area of an interferometry fringe. As shown in [5], both measurements yield identical frequency values. For the non-rotating dummy the strongest oscillations are observed in lower part of the crucible close to the axis.…”

“…Examples of temperature uctuations measured by the thermocouples and the interferometer, as well as corresponding cross-verication of the results can be found in [5]. The temperature oscillations appear with a certain frequency and its harmonics, whose values are obtained via the Fourier transform of the temperature histories measured by thermocouples, or by oscillations of the amount of black pixels in a control area of an interferometry fringe.…”

“…1 and is the same as described in [5], where the reader is addressed for details. Here we only mention that to mimic the Czochralski melt ow we study motion of experimental liquid in a transparent glass crucible whose sidewall and bottom are kept isothermal.…”

“…These studies were started by Schwabe and his co-authors (see [13] and references therein), involving at later stages also our research group [4]. We continue to carry out experiments of this kind [5,6], focusing, in particular, on producing of experimental data for validation of computational codes. Here we describe our rst results extended to a larger experimental facility and more precise measurements.…”