The oscillatory modes of thermal gravitational-capillary convection were simulated experimentally and numerically in an application to hydrodynamic model of Czochralski crystal growth. The experiments and calculations were carried out with using an ethanol as modelling fluid. The convection was dependent on the various temperature differences between the lateral crucible wall and the disk modelling the crystal: Delta T = 1-15K. Numerical simulation was based on complete Navier-Stokes-Boussinesq equations for axisymmetrical and three-dimensional cases. The features of transition from a stationary flow and heat transfer to its unstable modes accompanying with an occurrence and development of temperature pulsations were investigated. The clear graphic example of "cold plume" lifetime (its formation, development and pull-off under a crystal surface) has been shown. The spectral powers of temperature pulsations for different Delta T have been analysed. The unstable hydrodynamic modes were presented in a comparison with corresponding experimental data and its agreement has been established. (C) 2014 Elsevier B.V. All rights reserved.