Structure of a Flat Plate Boundary Layer Subjected to Free-Stream Turbulence

Abstract

The structure near the flat plate leading edge of an incompressible boundary layer subjected to freestream turbulence is investigated using large eddy simulation (LES) with a dynamic mixed subgridscale model. Free-stream turbulent intensities ranging from 1.5 to 10% are investigated. The evolutions of the velocity, temperature and turbulent intensity profiles inside the boundary layer and the characteristic length scales are analyzed and compared to a laminar flat plate boundary layer. The impact of the free-stream turbulence is examined for Reynolds numbers ranging from 0 (leading edge of the flat plate) to Re x ¼ 80; 000 by using two consecutive spatial LESs. Bypass transition is found to occur in the early stage of the boundary layer development for all five cases presented here. The analysis indicates that the thermal turbulent structures transfer more energy and hence generate more thermal fluctuations in their wake than the dynamic structures.

Development of flat-plate thermal and velocity boundary layers under highly turbulent and instable air flows: Reynolds numbers ranging from 8400 to 127000

“…A "wake region" appears in the profile which can be affected, if the boundary layer is thick (Re x = 126 900, Tu ∞ ≈ 12%), by the turbulence integral scale. Experimental results obtained for Tu ∞ = 6-12% are very close to those calculated by large eddy simulations for Tu ∞ = 10% [17]. They also confirm the production of turbulent energy inside the boundary layer.…”

“…Relation (3) does not fit the experimental results well and parameters admitted for a fully turbulent boundary layer (A = 0.37, n = 0.2) cannot be used. The present results can be compared to those calculated by Péneau et al [17] using Large Eddy Simulations for an air velocity of 1.23 m·s −1 and a turbulence intensity of 10% ( Fig. 4(b)).…”

“…The less pronounced thickening of the thermal boundary layer with Tu ∞ in comparison with the velocity boundary layer seems to contradict the results of Péneau et al [17]. The apparent contradiction between calculated and experimental results is probably due to the different starting conditions of development of the thermal boundary layer.…”

“…The range of free stream turbulence is wider than in Dyban and Epik's study and both temperature and velocity profiles are measured. Another work was carried out simultaneously by authors using large eddy simulation to better understand the effect of turbulence on heat transfers [17].…”

Selection of the Simulation Domain for Turbulent Flow Around an Airfoil

“…These studies are useful in order to understand near wake flows and also wake control. Peneau et al (2004) used an LES code to study free stream turbulence on the laminar flat plate boundary layer. Modeling consists of a flow field of 589,824 volumetric elements.…”