THE COALESCENCE OF TWO STAITIONARY DROPLETS: A NUMERICAL APPROACH

In this paper the three dimensional coalescence of two stationary head-on droplets withequal diameters are numerically investigated. The Navier-Stockes equations are solved inconjunction with the Volume of Fluid (VOF) method to track the free surface of the droplets.Furthermore, surface tension is added to the Navier-Stokes equations as the only body forcecausing the coalescence phenomenon. Water droplets are considered to have a sphericalshape with a specified gap size between their free surfaces. It is found that the coalescence ofstationary droplets driven by surface tension is due to the pressure variation in theirsurrounding fluid. It is also shown that for the coalescence to occur, the gap size has to beless than a certain limit called critical gap size. Finally, the effects of important parametersincluding surface tension and viscosity of surrounding gas on the critical gap size are studied.The results show that increasing the surface tension value increases the critical gap size. Incontrast, increasing the kinematic viscosity of surrounding gas decreases the critical gap size.

کلیدواژه ها:

Stationary coalescence phenomenon ، Critical gap size ، Surface tension ، VOF method