Journal of Fluid Mechanics



Papers

Direct numerical simulations of turbulent channel flow with transverse square bars on one wall


S. LEONARDI a1, P. ORLANDI a1, R. J. SMALLEY a2, L. DJENIDI a3 and R. A. ANTONIA a3
a1 Dipartimento di Meccanica e Aeronautica, Università Degli Studi di Roma “La Sapienza”, 00184, Rome, Italy
a2 Energy and Resources Research Institute, University of Leeds, Leeds LS2 9JT, UK
a3 Discipline of Mechanical Engineering, University of Newcastle, NSW 2308, Australia

Abstract

Direct numerical simulations have been carried out for a fully developed turbulent channel flow with a smooth upper wall and a lower wall consisting of square bars separated by a rectangular cavity. A wide range of $w/k$, the cavity width to roughness height ratio, was considered. For $w/k\,{\ge}\,7$, recirculation zones occur immediately upstream and downstream of each element while mean streamlines and spatial distributions of the skin frictional drag indicate that each element is virtually isolated. The maximum form drag occurs at $w/k\,{=}\,7$ and coincides with the minimum skin frictional drag. The dependence on $w/k$ of the Clauser roughness function reflects that of the form drag.

(Received May 15 2003)
(Revised June 15 2003)



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