A Simulation Study of the Turbulent Drag Reduction Mechanisms Derived from Shark Skin.pdf

JOURNAL OF CHINA ORDNANCE A Simulation Study of the Turbulent Drag Reduction Mechanisms Derived from Shark Skin HU Hal—bao(胡海豹)，SONG Bao—wei(宋保维)，LIU Guan—shan(刘冠杉)， GUO Xiao-juan(郭晓娟)，PAN Guang(潘光) (College of Marine。Northwestern Polytechnical University，Xi’an 710072 Shaanxi，China) Abstract：Through the numerical simulation investigation，the turbulent drag reduction mechanisms of shark riblet surface are explored．In allusion to the characteristics of riblets surface。the computation region．grids and flow parameters are dealt with reasonably．These present simulation results show preliminarily that 1)only the near-wall flow field above riblet sutraces is affected by riblets，and the flow within riblets is slow and quiescent；2)the viscous sub-layer above riblet surface is thicker；3)the shear stress and the loeal friction coefficient above the riblet surface are reduced，and the drag reduction quantity is larger at the bottom of fihlets than that at the top．Numerical simulation investigation on the riblet surface in the paper can provide a reference for future research in this field． Key Words：hydromechanics；riblet surface；drag reduction；flow field；near-wall CLC Number：0357．5 Document Code：A Article ID：1673—002X(2009)03—0168—07 Introduction As the energy issue becomes more and more threatening nowadays，how to save energy has been an urgent pursuance for human beings．One of the main methods to save energy is trying to reduce their skin．．friction drag in the designs of vehicles．The skin friction drag accounts for a large percentage in the to— tal drag of vehicles．For example，to a submarine， the friction drag takes more than 80％in its total drag；to a naval ship，the friction drag takes more than half of the total；to a long--distance transporta-- tion tube，nearly all forces of the pumps are used to overcome the friction drag．In most areas of the sur— face of these vehicles，the flow is turbulent flow． Therefore，the study on drag reduction technique of turbulent boundary layer is