Using quasi two-dimensional systems to understand large-scale vortical structures and dynamics
Using quasi two-dimensional systems to understand large-scale vortical structures and dynamics lead image
Researchers continue to investigate spatial dimension effects on turbulence by examining scaling laws for various quantities in quasi two-dimensional (2-D) systems. In Physics of Fluids, Hamid Kellay, an experimental physicist from the University of Bordeaux, describes how quasi 2D channels or pipe flows can bring new insights toward understanding fluid dynamics and friction drag.
In his article, Kellay describes how such quasi 2D channel flow experiments have uncovered a possible link between friction drag, a macroscopic quantity, and the turbulent energy spectrum of the turbulent fluctuations. Goldenfeld, and Gioia and Chakraborty started the work in this area by applying the roughness-induced criticality theory and momentum-transfer theory proposed by Goldenfeld, and Gioia and Chakraborty, respectively.
Notably, Gioia and Chakraborty’s theory derived an expression that is consistent with a scaling law derived by Goldenfeld whereby friction drag is a functional of the turbulent energy spectrum, rendering the expression useful, precisely predicting the macroscopic properties of turbulent flows.
Kellay also discusses prior work that studied vortices in soap bubbles, an investigational system that permits quasi 2D flows due to the bubble’s thin liquid film and curved surface. Soap bubbles help examine features, movement, and long-time dynamics related to large-scale vortical structures seen in natural turbulent flows like planetary atmospheres.
As an example, Kellay highlights findings from his own research that examined vortex intensity using a soap bubbles, in which he demonstrated long-lived vortices and well-defined intensification cycles with universal features.
Moving forward, Kellay emphasizes that quasi-2D flows empower researchers to further explore the generic properties of natural vortices, like tropical cyclones, which opens the door to understanding ways to manipulate turbulent fluctuations.
Source: “Hydrodynamics experiments with soap films and soap bubbles: A short review of recent experiments,” by H. Kellay, Physics of Fluids (2017). The article can be accessed at https://doi.org/10.1063/1.4986003 .
