(409i) Numerical Simulation for Multiple Bubble Interactions in Low Temperature Fluids

Mishra, A., Indian Institute of Technology Kharagpur 721302, West Bengal India
Ghosh, P., Indian Institute of Technology Kharagpur
Lakkaraju, R., Indian Institute of Technology Kharagpur
Mondal, J., Indian Institute of Technology Kharagpur

simulation for multiple bubble interactions in low
temperature fluids

Mondal; 1Arpit Mishra; 1Parthasarathi Ghosh; 2Rajaram

1Cryogenic Engineering Centre, Indian Institute of Technology,

2Department of Mechanical Engineering, Indian Institute of
Technology, Kharagpur

The interaction of vapor bubbles immersed
in any liquid throws open an array of outcomes depending upon the location and
time of its inception. The presence of any neighboring surface influences the above
phenomena leading to outcomes that range from unique bubble shape to formation
of jets. In literature, momentary and localized formation of 100 m/s jet of
liquid has been reported by Fong et al.1. Similarly, Chew et al.2 observed the
interaction of similar/dissimilar-sized bubbles in water for different
configurations that resulted in formation of different bubble shapes (e.g.
dumb-bell and mushroom). The outcome of bubble interaction – concentration
jets, vibration, sonoluminescence etc. holds good potential in certain
applications and hence necessitates further exploration. This can be utilized
in drug delivery in biological
channels, ultrasonic cleaning
3 etc. besides in
modern applications of cavitation-induced jets for nano-particle4
generation, sonoporation.                                                                                                                       

                The steeper
slope of the Clausius–Clapeyron curve5 for
cryogens compared to room temperature fluids makes it very sensitive to
temperature and pressure changes that accompany cavitation phenomenon. To add
with it, the relatively lesser values of density, viscosity, enthalpy of
vaporization6 ,
surface tension etc.  lead to altered dynamics of bubble interaction and
corresponding outcomes. Tomita7 has
numerically and experimentally investigated the energy transaction during
bubble collapse in liquid nitrogen. However, comparative studies are not
available for bubbles in low temperature boiling fluids. These fluids include
inert cryogenic liquids (e.g. liquid nitrogen or LN2) with boiling point lesser
than 123 K and its gaseous counterparts being permanent gases (e.g. N2
etc) can be easily bubbled without any undesirable reaction to the conduit.  In this paper, 3 cases of interaction of multiple
GN2 (gaseous nitrogen) bubbles in LN2 (liquid nitrogen) environment has been
compared with inception of similar configuration of air bubbles in water.
Computational fluid dynamics is used to analyze the outcomes of bubble
interaction e.g. shockwaves, liquid jet etc. simulated in compressible setup
using VOF (volume of fluid) method. The numerical model is validated with
experimental data and results are presented to wield a comparison between
bubble interactions in water and that in nitrogen. The liquid jet velocities obtained for a suitable
multi-bubble configuration in cryogenic environment can be almost more than
twice of that obtained for room temperature water, at certain location of jet

Figure: Jetting in water(left) and cryogenic (right) environment for a certain multi bubble configuration


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