Direct numerical simulation of primary breakup phenomena in liquid sheets

Abstract

Starting from the first experimental and analytical studies on primary breakup phenomena, many interesting results have been published in the past. It is known that in addition to the typical dimensionless groups (Reynolds and Weber number), inflow conditions can drastically influence primary breakup phenomena. Now that high computational resources are available, direct numerical simulation (DNS) has become a powerful tool in order to study primary breakup phenomena. Nevertheless only a few DNS studies concerning breakup phenomena and the influence of inflow conditions are available. This might be due to the fact that besides high demands of computational resources, sophisticated numerical models are also required in order to prescribe realistic inflow conditions and capture all length scales in the flow. This paper mainly focuses on the influence of different inflow conditions, such as the integral length scale or the fluctuation level inside the turbulent nozzle flow. For this, the breakup phenomena of water sheets at moderate Reynolds numbers injected into an quiescent air environment are considered. Since this study is performed as an numerical experiment by varying the character of the inflow velocity data, it was found that not only the mean axial velocity profile but also the integral length scale and the fluctuation level can have an influence on breakup phenomena.