An analysis of Bubble Migration in Horizontal Thermo-Capillarity Using the VOF Modeling (original) (raw)
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THERMOCAPILLARY MIGRATION OF BUBBLES AT LARGE REYNOLDS NUMBERS
International Journal of Multiphase Flow, 1998
AbstractÐThe thermocapillary movement of bubbles has been investigated for large Reynolds numbers. A numerical analysis of the¯ow ®eld around a bubble has been carried out for arbitrary Marangoni (Ma) numbers. For small Ma the¯ow ®eld has been calculated using a matched asymptotic procedure. A comparison is made of the nondimensional bubble velocity and the temperature gradient at the bubble surface, calculated numerically, with analytical results for large and small values of Ma, and with numerical results obtained previously. The expansion for large Ma has also been proposed by . For Maw1 the presence of both the thermal boundary layer and the wake impose limitations in the numerical calculations. The calculations have been carried out for values of Ma signi®cantly larger than those previously obtained. #
Thermocapillary bubble migration at high Reynolds and Marangoni numbers under low gravity
Journal of Colloid and Interface Science, 1996
Prandtl number ( Eq. [ 3 ] ) . Since a characteristic bubble The thermocapillary migration of single bubbles at high Reyvelocity cannot be determined a priori, the velocity U 0 nolds and Marangoni numbers has been investigated. Experiments derived from the tangential stress balance at the free suron the transient behavior of moving bubbles with Marangoni numface is used for scaling the migration velocity in Eqs. [1] bers up to Mg Å 2500 were carried out in the Bremen drop tower. and [ 2 ] : After a long heating period, a sufficiently linear temperature gradient was established with paraffin liquids. For 4.74 s of strongly reduced gravity the speed of the bubble migration was observed Here, s denotes the surface tension, h the dynamic viscosity, Key Words: thermocapillary bubble dynamic; low gravity experin the kinematic viscosity, a the temperature diffusivity, R ments; high Reynolds and Marangoni numbers.