DNS analysis of neck jetting flow dynamics after single drop impacting onto a preexisting liquid film

The present paper performs 2D numerical simulations for single drop impacting onto a at film, ubiquitous in spray utilizations, using DNS coupling with ACLS method. We analysis the liquid topology evolution and internal field information after impacts, highlighting the mechanisms of jetting flow in neck regions, and then extend the methodology to inclined cases. The adopted ACLS method is validated to be accurate with perfect mass conservation. The inclined angle is observed to positively affect the cavitation near gas-liquid interface. Further researches show that pressure gradient is the direct force for jetting flow in at cases. But the dominant mechanisms for front and back neck regions in inclined cases are different, i.e., pressure gradient is still the leading reason in the front while the vorticity becomes more important in the back for inclined cases. These two mechanisms are coexisting and competitive.