Experimental study of oscillatinggrid turbulence interacting with a solid boundaryTools McCorquodale, Mark W. and Munro, Richard J. (2017) Experimental study of oscillatinggrid turbulence interacting with a solid boundary. Journal of Fluid Mechanics, 813 . pp. 768798. ISSN 14697645
AbstractThe interaction between oscillatinggrid turbulence and a solid, impermeable boundary (positioned below, and aligned parallel to, the grid) is studied experimentally. Instantaneous velocity measurements, obtained using twodimensional particle imaging velocimetry in the vertical plane through the centre of the (horizontal) grid, are used to study the effect of the boundary on the rootmeansquare velocity components, the vertical flux of turbulent kinetic energy (TKE) and the terms in the Reynolds stress transport equation. Identified as a critical aspect of the interaction is the blocking of a vertical flux of TKE across the boundaryaffected region. Terms of the Reynolds stress transport equations show that the blocking of this energy flux acts to increase the boundarytangential turbulent velocity component, relative to the farfield trend, but not the boundarynormal velocity component. The results are compared with previous studies of the interaction between zeromeanshear turbulence and a solid boundary. In particular, the data reported here are in support of viscous and ‘returntoisotropy’ mechanisms governing the intercomponent energy transfer previously proposed, respectively, by Perot & Moin (J. Fluid Mech., vol. 295, 1995, pp. 199–227) and Walker et al. (J. Fluid Mech., vol. 320, 1996, pp. 19–51), although we note that these mechanisms are not independent of the blocking of energy flux and draw parallels to the related model proposed by Magnaudet (J. Fluid Mech., vol. 484, 2003, pp. 167–196).
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