Proceeding of Ninth International Symposium on Turbulence and Shear Flow Phenomena最新文献

{"title":"Rapid growth of unsteady finite-amplitude perturbations in a supersonic boundary-layer flow","authors":"Daisuke Watanabe, H. Maekawa","doi":"10.1615/tsfp9.510","DOIUrl":"https://doi.org/10.1615/tsfp9.510","url":null,"abstract":"Spatial numerical simulations (SNS) are performed to study transition to turbulence in a supersonic flat plate boundary layer forced by finite amplitude perturbations, where the freestream Mach numbers is 2.5 with the isothermal wall condition. Three-dimensional isotropic disturbances are superimposed on the laminar profile for Reynolds number based on the displacement thickness of 1000 at the inlet plane of the computational domain. The effects of the peak location of the disturbance spectrum and the magnitude distribution in the wall normal direction are analyzed. Numerical results indicate that energy spectra with a peak located at around the wavenumber of kmax=1.0 play an important role to induce transition to turbulence. The disturbance at lower wavenumbers with concomitant turbulence in the free stream shows an early appearance of hairpin-like structure in the transition region. The vortical structures on set of transition to turbulence rapid evolving to a hairpin packet with fine secondary structures downstream are shown in this paper, which is an inherent structure induces transition to turbulence in the supersonic boundary layer. INTRODUCTION A deep understanding of the principal route to turbulence in the wall-bounded shear flows is of great fundamental and practical interest. Various disturbances affect transition to turbulence in a laminar boundary layer, which has been investigated in detail so far. The primary stage of transition in a low-turbulence environment has been extensively studied by stability theories (Mack 1975) and flow fluctuation measurements by Kendall (1975) or Graziousi & Brown (2002). Understanding of the late stage of transition scenario or the nonlinear transition (Graziousi & Brown 2002) due to high level disturbances for boundary layers is even less pronounced especially for supersonic one due to experimental difficulties. In this study, a spatial simulation of a supersonic, isothermal flat plate boundary layer flow at Mach 2.5 is analyzed. Growth of finite amplitude disturbances on transition to turbulence in a developing boundary layer downstream require the application of fully spatial formation in a numerical simulation without extended temporal simplifying assumptions. The emphasis of this study is to assess the transitional scenarios for supersonic boundary layer and the late stage of streak breakdown and observing the transitional structures in a Lagrangian tracking manner, which leads to finding an inherent structure generated from finite-amplitude perturbations which induces transition to turbulence in the supersonic boundary layer. SMULATION DETAILS In the SNS of spatially developing boundary layer, the non-dimensional equations governing the conservation of mass, momentum, and energy for a compressible Newtonian fluid are solved. Note that displacement thickness at the inlet boundary layer (δ) is chosen to be a representative length scale. The computational domain size is Lx×Ly×Lz= 300×30×33. ","PeriodicalId":196124,"journal":{"name":"Proceeding of Ninth International Symposium on Turbulence and Shear Flow Phenomena","volume":"30 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114329082","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Flow-flame interaction in turbulent boundary layer flashback of swirl flames","authors":"D. Ebi, N. Clemens","doi":"10.1615/tsfp9.360","DOIUrl":"https://doi.org/10.1615/tsfp9.360","url":null,"abstract":"","PeriodicalId":196124,"journal":{"name":"Proceeding of Ninth International Symposium on Turbulence and Shear Flow Phenomena","volume":"8 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130365943","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"USE OF PROPER ORTHOGONAL DECOMPOSITION TO INVESTIGATE THE TURBULENT WAKE OF A SURFACE-MOUNTED FINITE SQUARE PRISM","authors":"R. Chakravarty, N. Moazamigoodarzi, D. Bergstrom, D. Sumner","doi":"10.1615/tsfp9.1110","DOIUrl":"https://doi.org/10.1615/tsfp9.1110","url":null,"abstract":"This study aims to investigate the characteristics of the instantaneous velocity field in select vertical planes located in the turbulent wake of a surface-mounted finite square prism. The instantaneous velocity field is obtained from a Large Eddy Simulation (LES); state-of-the-art post-processing methodologies namely the Proper Orthogonal Decomposition (POD) and the swirling strength criterion are used to analyse the flow structure. The study specifically considers the flow over a square prism of aspect ratio AR = 3 (AR = H/D where H is the height and D is the prism width) mounted on a ground plane and located within a thin laminar boundary layer. The Reynolds number based on the freestream velocity and cylinder width is Re = 500, and the angle of incidence is zero. POD is used to extract the dominant flow features, especially those related to vortex shedding, while the swirling strength criterion is used to visualise the smallscale turbulent structures. A principal conclusion of the study is that strong periodicity is observed in a transverse plane located 3.5D downstream of the prism, whereas the vertical mid-plane revealed a more complicated periodic structure. No compelling evidence of half-loop structures was obtained based on the analysis of the flow for a single periodic cycle. On the other hand, strong streamwise vortex structures were observed in the transverse plane in the upper region of the wake, somewhat reminiscent of but not the same as tip vortices. INTRODUCTION Flows over surface-mounted square prisms have been extensively studied in the literature. This flow is not only relevant from an industrial perspective in terms of flow over buildings and chimneys, but also from a research standpoint as the flow around the prism/cylinder and its turbulent wake exhibit multiple complex features. Many studies in the literature have focused on the time-averaged features of this flow, with relatively fewer studies investigating the instantaneous topologies of the flow field. While heuristic approaches have identified the different regions of the prism wake, some recent studies have attempted to propose a unifying flow theory based on the dynamics of the vortical structures shed from the prism. Wang and Zhou [1] suggested that the instantaneous flow tends to form arch-type vortices regardless of aspect ratio and is characterized by two spanwise vertical „legs‟ perpendicular to the ground plane and a connecting horizontal „bridge‟ at the free end. Based on probabilistic analysis and two-dimensional (2D) Particle Image Velocimetry (PIV) measurements, they developed a model of an outward-bulging arch vortex, which explains some of the mean flow characteristics in the wake downstream of the finite prism. More recently, Bourgeois et al. [2] proposed a different flow paradigm, namely the alternating half-loop vortex structure shed by the finite square prism into the wake. They indicated that the mean flow structure of the wake could be explained by ","PeriodicalId":196124,"journal":{"name":"Proceeding of Ninth International Symposium on Turbulence and Shear Flow Phenomena","volume":"44 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126561674","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"DNS OF THERMALLY-STRATIFIED TURBULENT BOUNDARY LAYERS SUBJECTED TO ADVERSE PRESSURE GRADIENT","authors":"H. Hattori, A. Kono, T. Houra, M. Tagawa","doi":"10.1615/tsfp9.1020","DOIUrl":"https://doi.org/10.1615/tsfp9.1020","url":null,"abstract":"","PeriodicalId":196124,"journal":{"name":"Proceeding of Ninth International Symposium on Turbulence and Shear Flow Phenomena","volume":"142 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131400942","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"EFFECTS OF TAYLOR-GORTLER VORTICES ON NEAR-WALL COHERENT STRUCTURES","authors":"Zixuan Yang, Bing-Chen Wang","doi":"10.1615/tsfp9.710","DOIUrl":"https://doi.org/10.1615/tsfp9.710","url":null,"abstract":"","PeriodicalId":196124,"journal":{"name":"Proceeding of Ninth International Symposium on Turbulence and Shear Flow Phenomena","volume":"133 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116342173","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"LARGE-EDDY SIMULATION OF HIGHLY-DISTURBED TURBULENT FLOWS IN A V-SHAPED RIB-ROUGHENED DUCT","authors":"Xingjun Fang, Bing-Chen Wang, Zixuan Yang, M. Tachie","doi":"10.1615/tsfp9.80","DOIUrl":"https://doi.org/10.1615/tsfp9.80","url":null,"abstract":"","PeriodicalId":196124,"journal":{"name":"Proceeding of Ninth International Symposium on Turbulence and Shear Flow Phenomena","volume":"14 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121634777","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"SPATIAL CORRELATION OF VELOCITY AND HEAT TRANSFER DOWNSTREAM OF A BACKWARD FACING STEP USING 2D-3C PIV AND IR THERMOGRAPHY","authors":"S. Yamada, Hajime Nakamura","doi":"10.1615/tsfp9.610","DOIUrl":"https://doi.org/10.1615/tsfp9.610","url":null,"abstract":"","PeriodicalId":196124,"journal":{"name":"Proceeding of Ninth International Symposium on Turbulence and Shear Flow Phenomena","volume":"5 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123894018","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"3D DNS OF METHANE-AIR TURBULENT PREMIXED FLAME IN THIN REACTION ZONES WITH A DETAILED KINETIC MECHANISM","authors":"Basmil Yenerdag, Y. Naka, M. Shimura, M. Tanahashi","doi":"10.1615/tsfp9.160","DOIUrl":"https://doi.org/10.1615/tsfp9.160","url":null,"abstract":"","PeriodicalId":196124,"journal":{"name":"Proceeding of Ninth International Symposium on Turbulence and Shear Flow Phenomena","volume":"31 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127056058","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"REALIZABLE DYNAMIC LES SUBGRID-SCALE MODELING","authors":"Stefan Heinz, Harish Gopalan, Ehsan Kazemi Foroushani, Michael K. Stoellinger, Reza Mokhtarpoor, Ponnampalam Balakumar","doi":"10.1615/tsfp9.120","DOIUrl":"https://doi.org/10.1615/tsfp9.120","url":null,"abstract":"It was shown recently that the use of stochastic analysis enables a theoretically well based systematic derivation of a realizable linear dynamic model (LDM) and a realizable nonlinear dynamic model (NDM). A-priori and a-posteriori analyses of turbulent channel flow and the turbulent Ek-man layer are used to study the characteristic properties of these dynamic models. The LDM and NDM are compared with other dynamic models: the non-stabilized and stabilized dynamic Smagorinsky model (DSM), which is used in many applications of LES, and Wang-Bergstrom’s dynamic model (WBDM), which represents an extension of the DSM. The DSM and WBDM do not represent realizable models because they are not derived as consequences of a realizable stochastic process. The comparisons re-ported here show that the LDM and NDM are based on a dynamic model formulation that avoids shortcomings of existing concepts. The LDM and NDM account","PeriodicalId":196124,"journal":{"name":"Proceeding of Ninth International Symposium on Turbulence and Shear Flow Phenomena","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129141313","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"INVESTIGATION OF A TURBULENT FLOW FROM THE TRANSITIONALLY ROUGH REGIME TO THE FULLY ROUGH REGIME","authors":"L. Chan, M. MacDonald, N. Hutchins, D. Chung, A. Ooi","doi":"10.1615/tsfp9.250","DOIUrl":"https://doi.org/10.1615/tsfp9.250","url":null,"abstract":"Direct Numerical Simulations (DNS) are carried out in a turbulent rough-wall pipe at low and medium Reynolds numbers. The rough surface, which is comprised of threedimensional sinusoidal roughness elements, was viscously scaled from the transitionally rough regime to the fully rough regime. The main aim of this study is to analyse the behaviour of the near-wall cycle as the surface condition changes from smooth through to fully rough. When analysing the streamwise velocity, a triple decomposition is used to distinguish between the fluctuations due to the spatial variation with the actual turbulent fluctuations. For small roughness height (h+ < 15), the near-wall cycle streaks occurs above the roughness elements. Although the high and low speed streaks look similar to the smooth wall when visually inspected, subtle differences are observed when the premultiplied energy spectra are analysed. When the flow is fully rough, the near-wall cycle is replaced by the stationary features of the flow which dominate within the roughness elements. We also analyse the contribution of the apparent wall shear stress due to form (pressure) drag (τR) expressed as a ratio between form and total shear stress (Rτ = τR τT ). In the fully rough regime, the form drag dominates (Rτ > 0.75) and disrupts the near-wall cycle. Townsend’s outer layer similarity is observed when the wall normal height normalised by the mean radius of the pipe y/R0 is greater than 0.56, where a collapse in the streamwise premultiplied energy spectra is obtained.","PeriodicalId":196124,"journal":{"name":"Proceeding of Ninth International Symposium on Turbulence and Shear Flow Phenomena","volume":"137 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122437184","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}