Inscrição na biblioteca: Guest
Início - ICHMT DL Ano atual Arquivos Comitê executivo Centro Internacional para Transferência de Calor e Massa

Instantaneous Fluctuation Velocity and Skewness Distributions Upstream of Transition Onset

DOI: 10.1615/ICHMT.2006.TurbulHeatMassTransf.290
pages 189-192

D. Hernon
Stokes Research Institute, Dept. Mechanical and Aeronautical Engineering, University of Limerick, Ireland

Edmond J. Walsh
Stokes Research Institute, Mechanical and Aeronautical Engineering Department, University of Limerick, Limerick, Ireland

Donald M. McEligot
Aerospace and Mechanical Engineering Department, University of Arizona,Tucson, AZ 85721; Idaho National Laboratory (INL), Idaho Falls, ID 83415-3885, USA; and Institut für Kernenergetik und Energiesysteme, Universitat Stuttgart, Stuttgart, Germany


The development of streamwise orientated disturbances through the boundary layer thickness prior to transition onset for zero-pressure gradient boundary layer flow under the influence 4.2 %Tu is presented. The analysis concentrates on the development of the maximum positive and negative of the fluctuation velocity in order to gain further insight into the transition process. The average location of the peak negative fluctuation velocity over a range of Reynolds numbers was measured in the upper portion of the boundary layer at y/δ ≈ 0.6, whereas the location of the peak positive value was measured at y/δ ≈ 0.3. The disturbance magnitude of the negative fluctuation velocity increased beyond that of the positive as transition onset approached. The distribution and disturbance magnitude of the maximum positive and negative fluctuation velocities indicate that the initiation of transition occurs on the low-speed components of the flow that are lifted up to the upper region of the boundary layer, in qualitative agreement with recent direct numerical simulations on the interaction between negative jets and small scale turbulence in the freestream during the transition process. The results presented in this investigation also demonstrate the increased physical insight gained by examining the distributions of the maximum positive and negative of the streamwise fluctuation velocity component associated with the low and high-speed streaks, compared to time-averaged values, in determining what structures cause the breakdown to turbulence.

ICHMT Digital Library

Bow shocks on a jet-like solid body shape. Thermal Sciences 2004, 2004. Pulsed, supersonic fuel jets - their characteristics and potential for improved diesel engine injection. PULSED, SUPERSONIC FUEL JETS - THEIR CHARACTERISTICS AND POTENTIAL FOR IMPROVED DIESEL ENGINE INJECTION
View of engine compartment components (left). Plots of temperature distributions in centreplane, forward of engine (right). CHT-04 - Advances in Computational Heat Transfer III, 2004. Devel... DEVELOPMENT AND CURRENT STATUS OF INDUSTRIAL THERMOFLUIDS CFD ANALYSIS
Pratt & Whitney's F-135 Joint Strike Fighter Engine under test in Florida is a 3600F class jet engine. TURBINE-09, 2009. Turbine airfoil leading edge stagnation aerodynamics and heat transfe... TURBINE AIRFOIL LEADING EDGE STAGNATION AERODYNAMICS AND HEAT TRANSFER - A REVIEW
Refractive index reconstructed field. (a) Second iteration. (b) Fourth iteration. Radiative Transfer - VI, 2010. Theoretical development for refractive index reconstruction from a radiative ... THEORETICAL DEVELOPMENT FOR REFRACTIVE INDEX RECONSTRUCTION FROM A RADIATIVE TRANSFER EQUATION-BASED ALGORITHM
Two inclusion test, four collimated sources. Radiative Transfer - VI, 2010. New developments in frequency domain optical tomography. Part II. Application with a L-BFGS associated to an inexa... NEW DEVELOPMENTS IN FREQUENCY DOMAIN OPTICAL TOMOGRAPHY. PART II. APPLICATION WITH A L-BFGS ASSOCIATED TO AN INEXACT LINE SEARCH