Random Turbulence Versus Structured Turbulence
Journal Title: INCAS BULLETIN - Year 2018, Vol 10, Issue 4
Abstract
The turbulence flows involve more or less the intermittent behavior of motions in two aspects. The first one is the so-called external intermittency associated with what is called partially turbulence flows, especially with the strongly irregular and convoluted structure (little understood) and random movement of the boundary between the turbulent and non-turbulent fluid. The second aspect is the so-called scale (small wave numbers) inertial or intrinsic intermittency and associated with spotty temporal (“bursting phenomenon”) and spatial patterns of the small scale structures at the fluid – solid interface. This structured turbulence of molecular thermal nature is called Lagrangian turbulence, in which a volume-preserving flow has flowlines which fill up regions of space ergodically. The origin and the self – sustaining mechanism of the structured turbulence are described in the sequel by means of the starting impact inducing three self-sustaining wave configurations which further are propagated in the flow field as vorticity wave packets of soliton type. The result of the whole process is easily observed in the form of hairpin vortex packets so-called 𝛺 – shaped coherent vortical structures, but is extremely difficult to interpret understand and explain. In this paper it is shown that hairpin vortex generation mechanism is governed by principle of “𝛺” momentum – energy invariance for elastic collisions constrained to slide frictionless on the contact surface.
Authors and Affiliations
Horia DUMITRESCU, Vladimir CARDOS, Radu BOGATEANU
Keywords
Related Articles
- EP ID EP419486
- DOI 10.13111/2066-8201.2018.10.4.5
- Views 88
- Downloads 0
REVLANSYS: Mission and GNC Design of Terminal Entry and Landing Missions for Advanced Re-Entry Vehicles
The ESA REVLANSYS study aims to develop key technologies in the field of Mission Engineering and GNC for autonomous re-entry vehicles, and to derive coherent mission, system and GNC requirements for the specific terminal...
Quality Management Principles as Illustrated by the Organization of Romanian Inter-War Factories. A Century of Romanian Industrial Tradition in Aeronautics
Inter-war Romania developed 6 aircraft factories, the first starting its activity in 1916. Four of these, with three located in Bucharest, produced over 2000 aircraft, maily for the military use as Romania entered the Se...
Drag coefficient modelling in the context of small launcher optimisation
The purpose of this paper is to present a fast mathematical model that can be used to quickly asses the drag coefficient for generic launcher configurations. The tool developed based on this mathematical model can be use...
Integrated CLOS and PN Guidance for Increased Effectiveness of Surface to Air Missiles
In this paper, a novel approach has been presented to integrate command to line-of-sight (CLOS) guidance and proportional navigation (PN) guidance in order to reduce miss distance and to increase the effectiveness of sur...
VTVL concept optimisation of the landing gear
Vertical takeoff, vertical landing (VTVL) is a subject of international interest at the moment thanks to the successful recovery of the Blue Origin vehicle. Aggressive weight targets with a short development time in the...