Azoui, HananeSoltani, N.Bahloul, D.2023-09-072023-09-0720182170-161X2588-2082http://hdl.handle.net/123456789/15257A three-dimensional numerical study of the convection heat transfer in a simulated Czochralski system is conducted .In this work, the numerical investigation were performed to analyze the free convection in the Czochralski crucible and the temperature fluctuations(thermal instabilities) just below the melt-crystal interface. We used the Finite Volume Method in cylindrical coordinates and the Fast Fourier Transform method for study the free convection, the temperature fluctuations 2 mm near the interface by taking into account the case of non-rotating crystal. In this study the heat transfer, thermal instabilities, melt natural convection, radiative heat transfer, Marangoni convection were conducted for Al2O3 melt in the crucible. Our objective is to show the fluctuations of temperature just below the interface by taking into account the effect of Rayleigh number for determining the crucible heating temperature value, and display the problem and his solution of the natural convection in the Czochralski crucible.enNatural convectionHeat transferSapphireCzochralski methodShaped crystalsThermal instabilitiesCrystal growthArticle