Intensity and angle-of-arrival spectra of laser light propagating through axially homogeneous buoyancy-driven turbulence

Pawar, Shashikant S and Arakeri, Jaywant H (2016) Intensity and angle-of-arrival spectra of laser light propagating through axially homogeneous buoyancy-driven turbulence. In: APPLIED OPTICS, 55 (22). pp. 5945-5952.

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Abstract

Frequency spectra obtained from the measurements of light intensity and angle of arrival (AOA) of parallel laser light propagating through the axially homogeneous, axisymmetric buoyancy-driven turbulent flow at high Rayleigh numbers in a long (length-to-diameter ratio of about 10) vertical tube are reported. The flow is driven by an unstable density difference created across the tube ends using brine and fresh water. The highest Rayleigh number is about 8 x 10(9). The aim of the present work is to find whether the conventional Obukhov-Corrsin scaling or Bolgiano-Obukhov (BO) scaling is obtained for the intensity and AOA spectra in the case of light propagation in a buoyancy-driven turbulent medium. Theoretical relations for the frequency spectra of log amplitude and AOA fluctuations developed for homogeneous isotropic turbulent media are modified for the buoyancy-driven flow in the present case to obtain the asymptotic scalings for the high and low frequency ranges. For low frequencies, the spectra of intensity and vertical AOA fluctuations obtained from measurements follow BO scaling, while scaling for the spectra of horizontal AOA fluctuations shows a small departure from BO scaling. (C) 2016 Optical Society of America

Item Type:	Journal Article
Publication:	APPLIED OPTICS
Additional Information:	Copy right for this article belongs to the OPTICAL SOC AMER, 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 USA
Department/Centre:	Division of Mechanical Sciences > Mechanical Engineering
Date Deposited:	08 Oct 2016 07:28
Last Modified:	08 Oct 2016 07:28
URI:	http://eprints.iisc.ac.in/id/eprint/54942

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