Direct Numerical Simulation On Shock-wave/turbulent-boundary-layer Interaction

Shock wave-turbulent boundary layer interaction(SWTBLI)is a common phenomenon in aeronautical engineering,and turbulence models are usually employed in numerically predicting its flow field.However,as pointed out by Dolling(2001)and confirmed by a more recent comprehensive analysis of Roy & Blottne(2006),the conventional turbulence models are all failed in providing a satisfactory prediction on the skin friction and the heat flux in the close neighbourhood of the interacting region.The reason is that the SWTBLI problem involves a certain number of complex physical phenomena,such as the flow separation and re-attachment,the low-frequency unsteadiness of the shock motion and the separation bubble,the enhancement of the pressure gradient and the turbulent fluctuation in the interaction region and the re-laminarization effects in the separation region.Since the mechanisms of these phenomena have not been well understood,the failure of the current works associating with the improvement of the turbulence models on the problem of SWTBLI are caused by the lack of the theoretical basis.In this dissertation,the oblique shock wave impinging on the turbulent boundary layer is selected as the physical model,and through direct numerical simulation(DNS),the whole physical process of the SWTBLI is studied.The results and conclusions are briefly summarized as follows:(1)By comparing with Pirzzoli & Bernardini(2011)and Morgan et al.(2013)'s results,it is verified that our numerical results are of high accuracy and hence are reliable.(2)Through analysis on the turbulent statistics,the coefficient of the surface friction,the pressure gradient,the heat flux,the mean flow profiles and the distributions of the Reynolds stress are obtained.These results can be used as a standard data-set on further investigations on turbulence modeling.Moreover,the characteristics of the reverse flow in the separation bubble is analyzed as well,which exhibits the phenomenon of the so-called 're-laminarization'.(3)The neal-wall law of the incompressible turbulent boundary layers with separation,as proposed by Skote & Henningson(2002),is extended to the compressible case,which is supposed to be valid on describing the mean velocity of the problem of SWTBLIs in the near-wall region.This argument is confirmed by our DNS data.