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Séminaire A. Urbano

10 novembre 2017

Nucleate boiling in micro-layer regime

Séminaire Annafederica Urbano

Jeudi 16 novembre à 12 h 30 salle Castex Rez de Chaussée

Séminaire du groupe Interface

Abstract :

The nucleation of a bubble can be characterized by the formation of a micro-layer underneath the bubble. The micro-layer, which has a thickness of a few microns, contributes strongly to the growth of the bubble due to the high heat fluxes that areinvolved. Therefore, understanding its formation is of fundamental importance from a physical perspective. On the other hand, neglecting the micro-layer formation with underesolved numerical simulations could lead to erronous results. The goal of the present work is to understand in which conditions a micro-layer is formed underneath a bubble and where is the limit between contact line and micro-layer regimes in terms of Jacob number and physical properties. Direct numerical simulations are carried out with the in house solver DIVA, developed at IMFT, for incompressible two phase flows with phase change. The physical processes involved in the formation and depletion of the micro-layer and the impact on the bubble growth are investigated for water at atmospheric pressure. Then, conditions for nucleate boiling in micro-layer or contact line regimes are deduced from a parametric study. An explanation of the physical mechanisms involved in the existence of a limit between the regimes is given.

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