NUMERICAL STUDY OF THERMOCAVITATION AT THE END OF AN OPTICAL FIBER PLACED IN A TUBE
V.A. Kosyakov1,2, R.V. Fursenko1,2
1Khristianovich Institute of Theoretical and Applied Mechanics, Siberian Branch of the Russian Academy of Sciences, Novosibirsk, Russia
2Institute of Applied Mathematics, Far Eastern Branch of the Russian Academy of Sciences, Vladivostok, Russia
Keywords: laser-induced subcooled boiling, single bubble, cumulative jet, numerical simulation, volume-of-fluid method
Abstract
The influence of tube walls on laser-induced subcooled boiling at the end of a thin laser fiber placed in a tube is investigated numerically. It is shown that, in the case of tubes with a radius fourfold greater than the bubble radius at maximum expansion, the velocity of the cumulative jet formed upon collapse of the vapor bubble is equal to that in an unbounded space. As the tube radius decreases, the jet velocity decreases due to rebound , which is bubble re-expansion that prevents jet formation. A further reduction in radius leads to a predominance of axial fluid flow within the tube and subsequent jet destruction. The influence of tube radius and length, as well as fiber length, on the bubble shape and volumetric flow rates through the tube end sections is demonstrated. Dimensionless parameters at which the volumetric flow rate through these sections reaches its maximum are identified, which is particularly important for medical applications.
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