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

{"title":"PIV OF A PRECESSING CYLINDER FLOW AT LARGE TILT ANGLES","authors":"T. Albrecht, H. Blackburn, P. Meunier, R. Manasseh, Juan M. Lopez","doi":"10.1615/tsfp9.830","DOIUrl":"https://doi.org/10.1615/tsfp9.830","url":null,"abstract":"Planar particle image velocimetry measurements of the flow in a precessing cylinder are presented for nutation angles of up to 15◦. For a case of a moderate Reynolds number, we observe a rapid transition to a disordered state with a brief appearance of structures of high azimuthal wave numbers. Similarity to observations reported in previous experiments and numerical simulations at much lower tilt angle, but higher Poincare number suggests, a triadic resonance as the transition mechanism. Amplitudes of the forced mode and the mean streaming flow are extracted; their scaling with Reynolds number is found to agree reasonably well with weakly nonlinear theory. INTRODUCTION AND BACKGROUND Rotating flows are present in the atmosphere, in oceans and lakes, and also in astrophysical and many technical applications. A rotating system allows for inertial waves to exist owing to the restoring effect of the Coriolis force. One way to excite inertial waves is precession, the simultaneous rotation around two axes as sketched in Figure 1: a cylinder, tilted through an angle α and rotating at an angular frequency Ω1, is mounted on a turntable which rotates at Ω2. Precession is considered as a possible driver for the geo-dynamo, i.e., the creation of Earth’s magnetic field. Also, liquid fuel in spin-stabilised spacecraft may be subject to precessional forcing, destabilising the whole spacecraft (Manasseh, 1993). Some types of instability and transition of rotating flows may be associated with Kelvin modes, the linear, inviscid eigenmodes of solid-body rotation flow. These modes are not solutions of the full Navier-Stokes equations with no-slip boundary conditions. Yet in the weakly nonlinear regime they have proven to be useful diagnostics of experimental and numerical observations (Meunier et al., 2008; Blackburn et al., 2014). Each Kelvin mode is characterised by three integer indices (n, l,m) corresponding to axial, radial, and azimuthal directions, respectively, and is associated with a frequency. Velocity components of Kelvin modes all have radial profiles ui(r), vi(r), wi(r) consisting H R α Ω1 Ω2","PeriodicalId":196124,"journal":{"name":"Proceeding of Ninth International Symposium on Turbulence and Shear Flow Phenomena","volume":"18 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":"131305801","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":"LAGRANGIAN EVOLUTION OF HAIRPIN STRUCTURES IN THE TEMPORAL TRANSITION IN CHANNEL FLOW","authors":"Yaomin Zhao, Yue Yang, Shiyi Chen","doi":"10.1615/tsfp9.1120","DOIUrl":"https://doi.org/10.1615/tsfp9.1120","url":null,"abstract":"","PeriodicalId":196124,"journal":{"name":"Proceeding of Ninth International Symposium on Turbulence and Shear Flow Phenomena","volume":"2 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":"115856520","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":"METHODS FOR UNDERSTANDING SHEAR INDUCED THROMBUS GROWTH","authors":"Isaac P. Pinar, J. Arthur, R. Andrews, E. Gardiner, K. Ryan, J. Carberry","doi":"10.1615/tsfp9.1210","DOIUrl":"https://doi.org/10.1615/tsfp9.1210","url":null,"abstract":"","PeriodicalId":196124,"journal":{"name":"Proceeding of Ninth International Symposium on Turbulence and Shear Flow Phenomena","volume":"87 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":"121258715","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 THE FLOW OVER A CONTOURED RAMP","authors":"C. Fureby, S. Zhu, David A. Jones","doi":"10.1615/tsfp9.110","DOIUrl":"https://doi.org/10.1615/tsfp9.110","url":null,"abstract":"Large Eddy Simulations (LES) have been used to simulate the development, separation, reattachment and downstream recovery of the flow over a smoothly contoured ramp. Five different subgrid models have been compared on a grid of intermediate resolution containing 19.2 million cells and the effect of grid resolution has been examined by studying the behavior of one model on four different grids varying between 2.4 and 153.6 million cells. All LES models capture the main flow features, but the results on the intermediate and fine grids generally show better agreement with the experimental data.","PeriodicalId":196124,"journal":{"name":"Proceeding of Ninth International Symposium on Turbulence and Shear Flow Phenomena","volume":"25 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":"125752150","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":"DIRECT NUMERICAL SIMULATION OF THE FLOW AROUND A WING SECTION USING HIGH-ORDER PARALLEL SPECTRAL METHODS","authors":"R. Vinuesa, S. M. Hosseini, A. Hanifi, D. Henningson, P. Schlatter","doi":"10.1615/tsfp9.300","DOIUrl":"https://doi.org/10.1615/tsfp9.300","url":null,"abstract":"The results of a DNS of the flow around a wing section represented by a NACA4412 profile, with Rec = 400,000 and 5◦ angle of attack, are presented in this study. The high-order spectral element code Nek5000 is used for the computations. An initial RANS simulation is used to define the velocity boundary conditions, and to design the computational mesh. The agreement between spanwiseand time-averaged fields from the DNS and the RANS simulation is excellent. The mean flow and several components of the Reynolds stress tensor at x/c = 0.4 (β = 0.53) and 0.8 (β = 4.54) are compared with the ZPG boundary layer computed by Schlatter & Örlü (2010). In both cases, the friction Reynolds number is roughly matched (330 and 450), and as expected the Reθ values from the wing (720 and 1,800) are larger than the ones from the ZPG case (612 and 1,007). The APG leads to a steeper log law, a more prominent wake region and a larger U+ e . The tangential turbulence intensity exhibits a stronger inner peak, and starts to develop an outer peak. We also show that the impact on the spanwise component is significant, and also on the wall-normal intensity and the Reynolds shear stress for stronger pressure gradients, especially in the outer region.","PeriodicalId":196124,"journal":{"name":"Proceeding of Ninth International Symposium on Turbulence and Shear Flow Phenomena","volume":"52 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":"126823055","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":"AN INVESTIGATION OF SONIC & SUPERSONIC AXISYMMETRIC JETS: CORRELATIONS BETWEEN FLOW PHYSICS AND FAR-FIELD NOISE","authors":"A. Magstadt, Matthew G. Berry, Z. Berger, Patrick R. Shea, M. Glauser, Christopher J. Ruscher, S. Gogineni","doi":"10.1615/tsfp9.400","DOIUrl":"https://doi.org/10.1615/tsfp9.400","url":null,"abstract":"An axisymmetric convergent jet is studied at ideal and underexpanded conditions using velocity and acoustic data. Time-resolved and large-window PIV capture near-field velocities and are simultaneously sampled with far-field microphones. POD is used to extract modes representative of physical processes in the flow. Specifically, screechcontaining and turbulent mixing modes are isolated in the supersonic case. The decoupled velocity fields are then correlated with acoustic data to identify modes related to specific noise spectra. Finally, selective flow reconstruction is carried out to reduce flow features associated with an imperfectly expanded jet. INTRODUCTION Understanding and reducing jet noise are difficult problems due to the inevitable turbulence encountered. The aerospace industry continues to invest considerable effort into mitigating jet noise as it creates unwanted acoustic pollution near airports, generates negative health consequences to flight deck crews, and compromises the stealth of military aircraft. Today, supersonic flight is becoming a standard for military aircraft and is being revisited for commercial applications. Furthering the understanding of turbulence in supersonic flow is a critical step towards noise source identification and suppression for future aircraft. While research in the area of aeroacoustics has progressed considerably since its introduction, Tam (1998), engine technologies are advancing at increasing rates, which push aircraft to greater speeds. Advanced designs utilize exotic nozzle and flow configurations to increase performance and abate noise generation in supersonic jets, Henderson et al. (2012). However, many of the heuristic solutions employed to date have been guided by partially anecdotal evidence, leaving incomplete understanding of the fluid mechanics involved. Prior to studying such configurations, the axisymmetric nozzle is revisited to interpret shock-turbulence interactions as anticipated in future designs. This prompted an investigation of supersonic noise generation in Syracuse University’s anechoic chamber. Current research is focused on identifying important flow features in a cold, axisymmetric convergent jet; in particular, sonic and supersonic flows are investigated to further recognize differences in noise generation associated with shocks. Particle imaging velocimetry (PIV) is simultaneously sampled with far-field pressures to allow for rigorous analyses. Reduced-order modeling (e.g. POD) of the jet plume in the streamwise plane (complementing work by Caraballo et al. (2003)), directivity and magnitude calculations of acoustic radiation, and correlations between the two measurements are carried out. Flow physics are then related to far-field noise signatures. Previously, subsonic test campaigns at Syracuse University’s Skytop Turbulence Laboratory by Low et al. (2013) and Berger et al. (2014) have presented evidence correlating deterministic spatial structures in the near-field flo","PeriodicalId":196124,"journal":{"name":"Proceeding of Ninth International Symposium on Turbulence and Shear Flow Phenomena","volume":"221 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":"123067232","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":"THE FLOW FIELD INSIDE A RANQUE-HILSCH VORTEX TUBE PART II: TURBULENCE MODELLING AND NUMERICAL SIMULATION","authors":"C. Morsbach, Daniel Schlüß, M. Franke, U. Doll, Eike Burow, M. Beversdorff, G. Stockhausen, C. Willert","doi":"10.1615/tsfp9.810","DOIUrl":"https://doi.org/10.1615/tsfp9.810","url":null,"abstract":"The flow in a Ranque-Hilsch vortex tube was investigated using turbulence models of different closure levels ranging from linear eddy viscosity over explicit algebraic Reynolds stress to differential Reynolds stress models. Unsteady flow features could be resolved with the differential Reynolds stress model. The results were validated against experimental data reported in part I of this paper and show qualitative as well as quantitative agreement. A detailed analysis of the flow topology as well as unsteady effects is presented.","PeriodicalId":196124,"journal":{"name":"Proceeding of Ninth International Symposium on Turbulence and Shear Flow Phenomena","volume":"11 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":"124498712","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":"NEAR-WALL BEHAVIOUR OF TRANSIENT FLOW IN A CHANNEL WITH DISTRIBUTED PYRAMID ROUGHNESS","authors":"M. Seddighi, S. He, D. Pokrajac, T. O'Donoghue, A. Vardy","doi":"10.1615/tsfp9.260","DOIUrl":"https://doi.org/10.1615/tsfp9.260","url":null,"abstract":"","PeriodicalId":196124,"journal":{"name":"Proceeding of Ninth International Symposium on Turbulence and Shear Flow Phenomena","volume":"3 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":"131420325","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":"ADAPTIVE CONTROL OF FINITE-AMPLITUDE 3D DISTURBANCES IN 2D BOUNDARY-LAYER FLOWS","authors":"N. Fabbiane, S. Bagheri, D. Henningson","doi":"10.1615/tsfp9.910","DOIUrl":"https://doi.org/10.1615/tsfp9.910","url":null,"abstract":"","PeriodicalId":196124,"journal":{"name":"Proceeding of Ninth International Symposium on Turbulence and Shear Flow Phenomena","volume":"172 9","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114015544","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":"CONDITIONAL MOMENT CLOSURE MODELLING FOR HCCI FEATURING COMPRESSION HEATING AND EXPANSION COOLING","authors":"F. Salehi, M. Talei, E. Hawkes, Ankit Bhagatwala, Jacqueline H. Chen, S. Kook","doi":"10.1615/tsfp9.370","DOIUrl":"https://doi.org/10.1615/tsfp9.370","url":null,"abstract":"This paper presents a conditional moment closure (CMC) model for ignition of a lean ethanol/air mixture under homogeneous charge compression ignition (HCCI) conditions. A set of direct numerical simulations (DNSs) presented by Bhagatwala et al. (2014) is used to evaluate the performance of the CMC model. The DNS data includes five cases with a mean temperature of 924 K and three different levels of thermal stratification. The effect of compression heating and expansion cooling is considered in the first three cases with T ′ = 15, 25 and 40 K. For this purpose, an inert mass source term is added to the governing equations. However, the other two cases with T ′ = 15 and 40 K do not consider compression heating and expansion cooling. The results show a better agreement between the CMC and DNS for cases in which compression heating and expansion cooling is considered. Further investigation of the DNS data shows that the contribution of the diffusion term in the CMC equations, representing the importance of deflagration mode, is only significant for the case which has the largest level of thermal stratification and does not involve compression heating and expansion cooling.","PeriodicalId":196124,"journal":{"name":"Proceeding of Ninth International Symposium on Turbulence and Shear Flow Phenomena","volume":"8 3","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114096832","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}