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A study on flow field measurement around growing and rising vapour bubbles by use of PIV technique is presented. Bubbles were generated from single artificial cavities. Experiments have been conducted with saturated boiling of distilled water at atmospheric pressure. In the experiment fluid velocity field surrounding the bubbles was visualized by use of polyamide tracer particles and a sheet of a YAG pulse laser beam. The images were recorded with a cross-correlation CCD-camera. It has been shown that for lower heat flux density bubble growths in an almost quiescent bulk of liquid. For higher heat flux density the train of bubbles creates a vapour column with strong wake effect. Maximum liquid velocity recorded is approximately equal to the terminal velocity of bubble rising in a stagnant liquid.

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There is no doubt today that thermal and thermocapillary convection play a dominant role in momentum, heat, and mass transfer in the Czochralski crystal growth method. Because of the complexity of the problems, measurements in one point of the volume are not sufficient to illuminate the flow topography or to compare the experimental results with real or numerically simulated data. Therefore, it is of great interest to measure the temperatures and velocities in the whole field in order to qualitatively analyze thermally driven convection. The new experimental particle image thermometry method, based on computer-aided color analysis of the TLCs reported here, enables the simultaneous determination of the temperature and velocity fields.