Topical Problems of Fluid Mechanics


Institute of Thermomechanics AS CR, v.v.i.	CTU in Prague Faculty of Mech. Engineering Dept. Tech. Mathematics	MIO Université du Sud Toulon Var - AMU - CNRS - IRD	Czech Pilot centre ERCOFTAC

Drag Evaluations on Rough Surfaces from Near-Wall Models
E. Friedmann , Y. Kim , Y. Ri
Abstract:
In this paper we evaluate the drag of periodic rough microstructures from near-wall models. With near-wall models we denote Coutte ows which describe the viscous boundary layer of turbulent ows. The structures inside this layer are not the optimal ones but can be used for a deeper understanding of the drag reducing mechanism of riblets due to a valid mathematical theory for viscous ows. Here, the numerical calculations can be validated and the developer calculation strategies can later be extended to the turbulent boundary layer. The focus of this paper is the evaluation of the drag of several microstructures for a better understanding of their action to the turbulent overow. The inuence of the structures will be visible trough a shift in the mean velocity profile which will be quantfied. Due to the fixed calculation domain and thus an altered sublayer thickness, the obtained drag values can not be easily compared. We will as well present a theory for the comparison of the drag of rough surfaces calculated from our near-wall models as one for the comparison of rough versus smooth surface.
Keywords:
Couette flow, finite elements, rough surfaces, drag

Fulltext: PDF DOI: https://doi.org/10.14311/TPFM.2017.016

In Proceedings Topical Problems of Fluid Mechanics 2017, Prague, 2017 Edited by David Šimurda and Tomáš Bodnár, pp. 117-130 ISBN 978-80-87012-61-1 (Print) ISSN 2336-5781 (Print)