The impact of a gravity current with a vertically mounted circular cylinder: An experimental study

The impact of a fully developed saline current with a vertically erected circular cylinder and its subsequent runup and rundown on the cylinder were investigated experimentally with the Laser Induced Fluorescence technique. Detailed behaviors of the entire process were examined qualitatively and quantitatively. Time history of the current´s highest position on the cylinder indicated that the whole process could be divided into three stages: impact, transition and quasi-steady stage, respectively. The impact stage could be directly related to the inertia of the incident current while the transition stage was affected by the development of the reverse fresh water flow around the cylinder and above the saline current. The maximum runup occurred in the transition stage. The quasi-steady stage started when the weak internal jump reflected from the cylinder for upstream. The subsequent disturbances to upstream were found to have a periodic characteristic possibly caused by chocking of the flow from reduced flow section area or driven by the vortex shedding process generated from the reversed upper fresh water flow around the cylinder.