By a News Reporter-Staff News Editor at Journal of Engineering -- A new study on Fluids Engineering is now available. According to news reporting originating in Launceston, Australia, by VerticalNews editors, the research stated, "Smooth and rough wall turbulent boundary layer profiles are frequently scaled using the wall shear velocity u*, thus it is important that u* is accurately known. This paper reviews and assesses several wall similarity techniques to determine u* and compares results with data from the total stress, Preston tube, and direct force methods."
The news reporters obtained a quote from the research from the University of Tasmania, "The performance of each method was investigated using experimental repeatability data of smooth and rough wall turbulent boundary layer profiles at Re-theta of 3330 and 4840, respectively, obtained using laser Doppler velocimetry (LDV) in a recirculating water tunnel. To validate the results, an analysis was also performed on the direct numerical simulation (DNS) data of Jimenez et al. (2010, 'Turbulent Boundary Layers and Channels at Moderate Reynolds Numbers,' J. Fluid Mech., 657, pp. 335-360) at Re-theta - 1968. The inner layer similarity methods of Bradshaw had low experimental uncertainty and accurately determined u* and epsilon for the DNS data and are the recommended wall similarity methods for turbulent boundary layer profile analysis. The outer layer similarity methods did not perform well, due to the need to simultaneously solve for three parameters: u*, epsilon, and Pi."
According to the news reporters, the research concluded: "It is strongly recommended that the u* values determined using wall similarity techniques are independently verified using another method such as the total stress or direct force methods."
For more information on this research see: The Application of Wall Similarity Techniques to Determine Wall Shear Velocity in Smooth and Rough Wall Turbulent Boundary Layers. Journal of Fluids Engineering-Transactions of the ASME, 2014;136(5):49-58. Journal of Fluids Engineering-Transactions of the ASME can be contacted at: Asme, Two Park Ave, New York, NY 10016-5990, USA.
Our news correspondents report that additional information may be obtained by contacting J.M. Walker, University of Tasmania, Australian Maritime College, Natl Center Maritime Engn & Hydrodynam, Launceston, Tas 7248, Australia.
Keywords for this news article include: Launceston, Fluids Engineering, Australia and New Zealand
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