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Scaling Laws of Turbulent Diffusion - An Experimental Validation

Kinzel, Matthias and Holzner, Markus and Lüthi, Beat and Tropea, Cameron and Kinzelbach, Wolfgang and Oberlack, Martin (2008):
Scaling Laws of Turbulent Diffusion - An Experimental Validation.
In: 14th International Symposium on Applications of Laser Techniques to Fluid Mechanics, Lisbon, Portugal, 7-10 July, 2008, In: 14th International Symposium on Applications of Laser Techniques to Fluid Mechanics, Lisbon, Portugal, 7-10 July, 2008, [Conference or Workshop Item]

Abstract

From Lie-group (symmetry) analysis of the multi-point correlation equation Oberlack and Guenther Fluid Dyn. Res. 33, 453-476 (2003) found three different solutions for the diffusion of shear-free turbulence: (i) a heat equation like solution when the turbulence diffuses freely into the adjacent calm fluid, (ii) a deceleration wave like solution when there is an upper bound for the integral length scale and (iii) a finite domain solution for the case when rotation is applied to the system. This paper deals with the experimental validation of the theory. We use an oscillating grid to generate turbulence in a water tank and PIV (Particle Image Velocimetry) to determine the two-dimensional velocity and out-of-plane vorticity components. The whole setup is placed on a rotating table. After the forcing is initiated, a turbulent layer develops that is separated from the initially irrotational fluid by a sharp interface, the so-called turbulent/nonturbulent interface (TNTI). The turbulent region grows in time through entrainment of surrounding fluid. We measure the propagation of the TNTI and find good agreement with the theoretical prediction for all three cases.

Item Type: Conference or Workshop Item
Erschienen: 2008
Creators: Kinzel, Matthias and Holzner, Markus and Lüthi, Beat and Tropea, Cameron and Kinzelbach, Wolfgang and Oberlack, Martin
Title: Scaling Laws of Turbulent Diffusion - An Experimental Validation
Language: English
Abstract:

From Lie-group (symmetry) analysis of the multi-point correlation equation Oberlack and Guenther Fluid Dyn. Res. 33, 453-476 (2003) found three different solutions for the diffusion of shear-free turbulence: (i) a heat equation like solution when the turbulence diffuses freely into the adjacent calm fluid, (ii) a deceleration wave like solution when there is an upper bound for the integral length scale and (iii) a finite domain solution for the case when rotation is applied to the system. This paper deals with the experimental validation of the theory. We use an oscillating grid to generate turbulence in a water tank and PIV (Particle Image Velocimetry) to determine the two-dimensional velocity and out-of-plane vorticity components. The whole setup is placed on a rotating table. After the forcing is initiated, a turbulent layer develops that is separated from the initially irrotational fluid by a sharp interface, the so-called turbulent/nonturbulent interface (TNTI). The turbulent region grows in time through entrainment of surrounding fluid. We measure the propagation of the TNTI and find good agreement with the theoretical prediction for all three cases.

Title of Book: 14th International Symposium on Applications of Laser Techniques to Fluid Mechanics, Lisbon, Portugal, 7-10 July, 2008
Divisions: 16 Department of Mechanical Engineering > Fluid Dynamics (fdy)
16 Department of Mechanical Engineering
Event Title: 14th International Symposium on Applications of Laser Techniques to Fluid Mechanics
Event Location: Lisbon, Portugal
Event Dates: 7-10 July, 2008
Date Deposited: 02 Sep 2011 13:15
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