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Free-surface vortices have long been studied to develop an understanding of similar rotating flow phenomena observed in nature and technology. However, a complete description of its turbulent three-dimensional flow field still remains elusive. In contrast, the related Taylor-Couette flow system has been well explicated which classically exhibits successive instability phases manifested in so-called Taylor vortices. In this study, observations made on the turbulent free-surface vortex revealed distinguishable, time-dependent “Taylor-like” vortices in the secondary flow field similar to the Taylor-Couette flow system. The observations were enabled by an original application of 2D ultrasonic Doppler velocity profiling complemented with laser induced fluorescence dye observations. Additional confirmation was provided by three-dimensional numerical simulations. Using Rayleigh’s stability criterion, we analytically show that a wall bounded free-surface vortex can indeed become unstable due to a centrifugal driving force in a similar manner to the Taylor-Couette flow. Consequently, it is proposed that the free-surface vortex can be treated analogously to the Taylor-Couette flow permitting advanced conclusions to be drawn on its flow structure and the various states of free-surface vortex flow stability.

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Laparoscopic splenectomy has been safely performed for small spleens, but technical limitations have prevented massive splenectomy. We describe a technique of early hilar devascularization to enable massive splenectomy in three patients over the age of 80 years. Massive splenectomy was performed with minimal blood loss and minor morbidity. Early laparoscopic control of the splenic artery and vein will enable the safe removal of the massive spleen, without major laparotomy. Morbidity of splenectomy may be reduced by laparoscopy.