The front tracking method (FTM), which can track the maker points and capture the changes of the interface accurately was used to simulate the phenomenon of bubble coalescence. All governing equations were solved by using a second-order accurate project method, using centered-differences on a fixed, staggered grid and considering the effect of surface tension at the interface. The numerical simulations were compared with experimental and computational results from other literatures which modified the accuracy of calculation model. In this work, the rising process of coaxial bubbles and the process after fusion were analyzed in detail, and the existence of specific initial angle ?c and the relationship between ?c and Eotvos number (Eo) were analyzed. It was found that the rising velocity of both bubbles were higher than single bubble, and the coalesced bubble had the equal velocity with equivalent diameter single bubble in the rising process of coaxial double bubbles. The trailing bubble had higher velocity with the shorter distance of bubbles. In the range of Eo of leading bubble was 0.36~9, the time of rising stage was shorter and the time of contact stage was longer when the Eo of leading bubble increased. During contact stage, the thickness of liquid film between bubbles decreased because of the effect of pressure. Liquid film broke and coalescence of bubbles happened in the coalescence moment. The required time of coalescence increased as the distance of bubbles or Eo increased. However, the required time was stable as Eo was larger than 4.16. When the Morton number (Mo) was 0.57 and the range of Eo of leading bubble was 5.04~18.72, it was found that there was a specific initial angle ?c. The two bubbles repelled each other for 0?≤?≤?c but merge for ?c≤?≤90?, and ?c decreased with the increase of Eo.
Jie LEI Yu WANG Ming MA Peisheng LI Ying ZHANG
. Numerical simulation of coalescence of double bubbles using FTM[J]. The Chinese Journal of Process Engineering, 2019
, 19(2)
: 263
-270
.
DOI: 10.12034/j.issn.1009-606X.218221
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