On the helical behavior of turbulence in the ship wake

TL;DR

This paper investigates how helicity influences the structure and expansion of turbulent ship wakes, addressing discrepancies between experimental observations and theoretical predictions about wake divergence.

Contribution

It introduces the consideration of helicity in modeling turbulent ship wakes, providing insights into their slower expansion and structural differences.

Findings

Helicity affects the divergence rate of ship wakes.

Helical models better explain the slow expansion of wakes.

Differences between internal and external turbulence are clarified.

Abstract

Turbulent ship wake conservation at a long distance is one of unsolved problems at present. It is well known that wakes have a rotational structure and slowly expand with distance. Nevertheless, experimental data on their structure and properties are not sufficient. On the other hand, these experimental data show that the divergence of wakes does not change according to the law 1/5, as predicted by the theory. In our work we study the effect of helicity on the parameters of a turbulent ship wake. Taking into account the helical nature of the wake, we can clarify the difference between turbulence inside and outside of the wake on the one hand, and slow its expansion with time.