Resources

Author(s): Artur Gesla and Eunok Yim This study investigates the formation of the helical vortex rope in a Francis hydropower turbine by treating it as an unstable vortex breakdown mode in a simplified laminar flow. The vortex rope emerges through a supercritical Hopf bifurcation from an axisymmetric base flow in the draft tube. Without wall friction, a central recirculation zone develops, revealing subcritical solutions and hysteresis under partial...

Author(s): Pim J. Dekker, Christian Diddens, Marjolein N. van der Linden, and Detlef Lohse Surface tension is frequently measured with the pendant drop method, while the ambient humidity is usually an afterthought. With carefully calibrated experiments and detailed numerical simulations, we show that evaporative cooling lowers the drop temperature by up to 9.5 K which in turn raises the measured surface tension by more than 1 mN/m. Evaporation...

Author(s): Nianhua Liu and Serhiy Yarusevych Lifting surfaces operating at aerodynamically low Reynolds numbers often have laminar separation bubbles (LSBs) whose characteristics can significantly affect performance. We investigate the effect of localized surface roughness, which might form due to manufacturing, local contamination, damage or icing, on LSBs. We find that the localized roughness eliminates downstream laminar separation and modifies...

Author(s): Lin-Ling Li (李临玲), Juan-Cheng Yang (阳倦成), and Ming-Jiu Ni (倪明玖) Compared with a static liquid film, gas jet impingement on a flowing liquid metal film produces a shallower cavity and a strongly asymmetric profile through upstream liquid accumulation. Counter-current coupling upstream and co-current coupling downstream cause the wave-amplitude response to jet momentum to weaken upstream but strengthen downstream as the liquid Reynolds...

Author(s): Marek Stastna and Andrew P. Grace This article presents a simple to implement algorithm for detecting strong cabbeling in stratified fluids with a nonlinear equation of state. The algorithm is used to identify the manner in which the arrested development of the Rayleigh-Taylor instability occurs in the strongly cabbeling regime. [Phys. Rev. Fluids 11, 084505] Published Mon Aug 31, 2026

Author(s): Sedat Tardu and Benjamin Arrondeau Large staggered roughness elements in the entrance region of a subcritical channel flow generate intense turbulent eddies that gradually break down as the flow progresses into the downstream smooth channel (SC) of the configuration studied here. This flow combines several sources of complexity: surface roughness, a rough-to-smooth step change and relaminarization. The characteristics of the turbulence...

Author(s): H. A. J. Middleton-Spencer, B. McCanna, D. Proment, and H. M. Price Vortex reconnections are fundamental to quantum fluids. They are reconnections of quantum vortices defined by a topological change and irreversible energy transfer given by universal scaling laws, leading to quantum turbulence. We generalize this mechanism by studying reconnections of extra-dimensional quantum vortices. We find a new range of vortex interactions depending...