CIRCULAR HYDRAULIC JUMP

GENERAL

The study about the circular hydraulic jump merits special attention due to the widespread use of diverging stilling basins and because the governing equations of this phenomenon differ significantly from those for a hydraulic jump in a channel with constant cross section. When a jet of water impinges vertically on a flat surface, it can be seen that from the point of impingement, the water spreads out radially in a thin film, and beyond a certain distance, the height of the fluid layer abruptly increases, exhibiting the circular hydraulic jump. Jets impinging on horizontal surfaces can be used to cleanse metal surfaces, induce atomisation and effect high heat transfer. In this blog, an attempt is made to explain the circular hydraulic jump and its characteristics based on the work done by Bush et al., (2005) , Kensuke and Feng (1998) and Avedisian and Zhao(2000).

It is seen that the transition from type I to type II circular hydraulic jump is associated with an increase in pressure beneath the surface in the region after the hydraulic jump. Steady state circular hydraulic jump diameter is larger at low gravity than normal gravity but the curvature across circular hydraulic jump is higher at normal gravity than at low gravity. The length of transition zone from upstream to downstream height increases as gravity is reduced. Surface tension plays an important role on the circular hydraulic jump stability and the influence of surface tension and viscosity dominate at low gravity. Impingement of a circular liquid jet onto a solid surface is important in a variety of cooling processes.