Comparisons of Single Drop Impact Simulations with Experiments

As the size of electronic equipment is reduced, the ability to reject waste heat is also reduced due to smaller component surface areas, thereby affecting the component performance and finally leading to the damage of the component. Spray cooling offers a means to achieve high rates of heat transfer from microelectronic components and other high energy density devices.;As a first step in investigating spray cooling, a single liquid drop impacting onto a thin liquid film was studied at isothermal conditions. 2D axisymmetric cases were simulated with ANSYS Fluent and 3D cases with OpenFOAM using the Volume of Fluid (VOF) model. The post processing of the results was performed in Surfer (Version 9) software in order to determine the liquid film thickness and then calculate the volume of the liquid under the cavity (sub-cavity liquid volume) as functions of time. These simulations agreed with the experimental data during the cavity formation phase, but did not closely match with the experiments during the refilling of the cavity in the majority of the cases. It was speculated that the discrepancies could be due to the three dimensional instabilities leading to droplet ejection from the crown during the retraction phase. These instabilities are omitted from the 2D simulations, and were not adequately resolved in the 3D simulations. For this reason, identical cases were simulated in 3D in OpenFOAM using the VOF model. The improved agreement with experiments obtained with the three dimensional simulations is discussed.