Persistence behaviour of heat and momentum fluxes in convective surface layer turbulence

TL;DR

This paper investigates the persistence patterns of heat and momentum fluxes in convective turbulence, revealing distinct behaviors, power-law scaling, and insights into flux generation mechanisms that enhance understanding of turbulence dynamics.

Contribution

It uncovers the differing persistence behaviors of heat and momentum fluxes and links these to turbulent structures and scaling laws, advancing turbulence theory.

Findings

Persistence patterns for heat and momentum fluxes differ significantly.

Power-law scaling laws are identified for turbulent motions.

Separation of flux phases explains transfer efficiency differences.

Abstract

The characterization of heat and momentum fluxes in wall-bounded turbulence is of paramount importance for a plethora of applications, ranging from engineering to Earth sciences. However, how the turbulent structures associated with velocity and temperature fluctuations interact to produce the emergent flux signatures, is not evident till date. In this work, we investigate this fundamental issue by studying the switching patterns of intermittently occurring turbulent fluctuations from one state to another, a phenomenon called persistence. We discover that the persistence patterns for heat and momentum fluxes are widely different. Moreover, we uncover power-law scaling and length scales of turbulent motions that cause this behavior. Furthermore, by separating the phases and amplitudes of flux events, we explain the origin and differences between heat and momentum transfer efficiencies in convective turbulence. Our findings provide new understanding on the connection between flow organization and flux generation mechanisms, two cornerstones of turbulence research.