MANIFESTATIONS OF VORTEX BEHAVIOR OF FLUIDS IN VARIOUS PHYSICAL EXPERIMENTS

Abstract

The paper presents a comprehensive examination of experimental manifestations of vortex behaviour in fluids, focusing on phenomena generated by physical mechanisms of fundamentally different nature. Through a systematic analysis of diverse hydrodynamic systems, this work demonstrates that nonlinear vortical dynamics represents an inherent and fundamental element of fluid motion across multiple spatial and temporal scales. The study employs a range of illustrative examples, beginning with Albert Einstein's classical "small experiment" and the formation and evolution of meanders in lowland river channels. These seemingly simple phenomena are shown to be governed by the same underlying principles that drive more complex hydrodynamic instabilities. Particular attention is devoted to the development of Rayleigh-Taylor-type vortical instabilities, which are characterized by the mutual "overturning" of heavy and light fluid components in a flowing medium. The paper explores these instabilities through experimental configurations, including thermal convection processes and the formation of "underwater crater" structures in granular materials settling through liquids. A central theoretical framework is established through the identification of common universal features of vortical excitations, all of which are fundamentally linked to the classical Helmholtz vortices in ideal fluid dynamics. The authors demonstrate that despite the diversity of mechanisms generating vortex behavior in real fluids, and the wide range of conditions under which such behavior manifests, there exist universal properties stemming from their connection to Helmholtz vortices. This unifying approach contributes significantly to the formation of a coherent theoretical framework capable of describing a remarkably broad spectrum of physical phenomena observed both in nature and in controlled laboratory experiments, from microscale optical self-defocusing patterns to astronomical structures like the Crab Nebula.