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

{"title":"EFFECTS OF PERTURBATIONS INDUCED BY FRACTURED STENT ON SECONDARY FLOW STRUCTURES IN A CURVED ARTERY MODEL","authors":"Kartik V. Bulusu, Christopher J. Popma, M. Plesniak","doi":"10.1615/tsfp8.1630","DOIUrl":"https://doi.org/10.1615/tsfp8.1630","url":null,"abstract":"","PeriodicalId":206337,"journal":{"name":"Proceeding of Eighth 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":"124219885","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":"EXPERIMENTAL STUDY OF REPRODUCIBILITY OF INSTANTANEOUS STRUCTURE OF THE DETERMINISTIC WALL TURBULENCE","authors":"V. Borodulin, Y. Kachanov","doi":"10.1615/tsfp8.240","DOIUrl":"https://doi.org/10.1615/tsfp8.240","url":null,"abstract":"","PeriodicalId":206337,"journal":{"name":"Proceeding of Eighth International Symposium on Turbulence and Shear Flow Phenomena","volume":"78 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":"123192879","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 SIMULATIONS AND PARTICLE IMAGE VELOCIMETRY EXPERIMENTS WITHIN A BIMHV FLOW NEAR PEAK SYSTOLE","authors":"A. Blackmore, P. Sullivan","doi":"10.1615/tsfp8.1640","DOIUrl":"https://doi.org/10.1615/tsfp8.1640","url":null,"abstract":"","PeriodicalId":206337,"journal":{"name":"Proceeding of Eighth International Symposium on Turbulence and Shear Flow Phenomena","volume":"41 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":"121700615","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 TURBULENT MIXING LAYERS WITH PERIODIC FORCING INDUCED INFLOW","authors":"Y. Kametani, Masayuki Kawagoe, K. Fukagata","doi":"10.1615/tsfp8.2140","DOIUrl":"https://doi.org/10.1615/tsfp8.2140","url":null,"abstract":"The direct numerical simulation of the turbulent mixing layer with periodically-forced inflow is performed. The angular frequency Ωc was set as a control parameter. To compare the experimental study of Naka et al. (2010), the angular frequency is set to be Ω = 0.83 (Case A) and 3.85 (Case B). In the present simulation, the momentum thickness shows the Case A achieved the mixing enhancement, while Case B achieves its suppression. Due to the both controls, the Reynolds normal shear stress, especially v′v′ increases behind the periodic forcing. The Reynolds shear stress u′v′ is suppressed in the Case B at downstream. This region is agree with that the mixing suppression is found in the momentum thickness. Furthermore, the anisotropic tensor indicates that two dimensional large coherent structure is generated in the Case B in which mixing was suppressed. Introduction A mixing layer is one of the fundamental free shear flow generated by the velocity gap (Brown & Roshko (2009)). In order to understand the vortex dynamics in shear flows, mixing layers have extensively been studied since Brown & Roshko (1974) experimentally visualized the coherent structure in turbulent mixing layers. Huang & Ho (1990) experimentally studied an acoustically perturbed laminar mixing layer and observed small-scale turbulence created due to interaction of spanwise and streamwise structures after the merging of spanwise vortices. Turbulent mixing layers can be found in various practical applications: e.g., inside combustion chambers and around the exhaust of turbo engines. Techniques for mixing enhancement or suppression are sometimes needed for efficient combustion or noise reduction. Ho (1982) attempted to control the mixing layer by perturbing the flow rates of inflows. They show that the spreading rate of a mixing layer can be manipulated at very low forcing level if the mixing layer is perturbed near a subharmonic of the most-amplified frequency. Naka et al. (2010) studied a mixing layer periodically forced by using a flap-type actuator made of piezoplastic (Polyvinylidene fluoride: PVDF) film aiming at both enhancement and suppression of mixing. They conclude that at some parameters of forcing mixing suppression can also be achieved. In the present study, direct numerical simulation (DNS) of turbulent mixing layers with periodic forcing, which mimics that by the flap-type actuator of Naka et al. (2010), is performed. The forcing by the flap-type actuator is modeled by transversely oscillating the inflow turbulent boundary layers. Direct numerical simulation The governing equations are the incompressible continuity and Navier-Stokes equations as following,","PeriodicalId":206337,"journal":{"name":"Proceeding of Eighth International Symposium on Turbulence and Shear Flow Phenomena","volume":"61 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":"126374853","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":"SCALING OF SMALL-SCALE MOTIONS IN WALL-BOUNDED TURBULENT FLOWS","authors":"Liangyan Wei, G. Elsinga, G. Brethouwer, P. Schlatter, A. Johansson","doi":"10.1615/tsfp8.680","DOIUrl":"https://doi.org/10.1615/tsfp8.680","url":null,"abstract":"The objective is to investigate flow topology and related Reynolds-number scaling in the eigenframe of the strain-rate tensor for wall-bounded turbulent flows. The databases used in the current stu ...","PeriodicalId":206337,"journal":{"name":"Proceeding of Eighth International Symposium on Turbulence and Shear Flow Phenomena","volume":"40 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":"128136755","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":"SCALAR MIXING AT TURBULENT/NON-TURBULENT INTERFACE OF A TURBULENT PLANE JET","authors":"R. Taveira, C. B. da Silva","doi":"10.1615/tsfp8.520","DOIUrl":"https://doi.org/10.1615/tsfp8.520","url":null,"abstract":"The interface region that bounds fully developed turbulent shear flow from the vortical non-vortical regions in free shear flows is a long-standing issue in turbulence research. Understanding the local dynamics that take place at such interfacial layer are key to the study of turbulent mixing and entrainment. Dimotakis (2005) highlights the importance of studying the mixing process of a passive scalar in a wide range of engineering applications, e.g. combustion. Recent investigations on the topic focused in the analysis of the properties of both the T/NT interface, particularly in the vorticity structures close to the T/NT interface. da Silva & Taveira (2010) and Reis et al. (2011) investigated these structures showing that the T/NT interface is made of these turbulent structures. Moreover, Reis et al. (2011) and Taveira & da Silva (2013) studied the role of vorticity structures in the enstrophy and kinetic energy transport across the T/NT interface, respectively. The present study aims to explain the dynamics of the turbulent mixing of a passive scalar through the study of scalar gradient and fluctuations transport mechanisms. It is also investigated the topology of the scalar gradient structures, which are responsible for the transport of scalar fluctuations. The present study aims to explain the dynamics of the turbulent mixing of a passive scalar through the study of scalar gradient and fluctuations transport mechanisms. It is also investigated the topology of the scalar gradient structures, which are responsible for the transport of scalar fluctuations. The present work uses data from a single direct numerical simulation of a turbulent plane jet at Reynolds number of Re = 140 and the Schmidt number is 0.7. Structure tracking and conditional statistics are employed allowing to filter out intermittence and a clear perspective of the local dynamics. The instantaneous fields showed that the passive scalar field is mainly arranged in intense scalar gradient sheets that are found along regions of persistent strain, in particular at the T/NT interface. However at the moderate Reynolds number these sheets are not flat as reported in literature, and are seldom arranged parallely. The jump in the mean conditional scalar as width of the order of the Taylor scale, in agreement with Westerweel et al. (2009). Conversely, the jump in the scalar gradient conditional profile suggests the sheet structures to have an average width of the order of the Kolmogorov scale. The topological analysis of the structures shows that on average the intense scalar gradient sheets have a thickness of ≈ 3η and a length of ≈ 2λ . The conditional analysis of the scalar gradient and variance transport revealed that the mixing is taking place particularly close to the T/NT interface, over a region with a thickness of ≈ 12−15η . Introduction In free shear flows, such as jets, sharp and intricate layers separate the irrotational region from the turbulent flow core. These layers est","PeriodicalId":206337,"journal":{"name":"Proceeding of Eighth International Symposium on Turbulence and Shear Flow Phenomena","volume":"41 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":"115835058","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":"PIV CHARACTERISATION OF A FLOW SEPARATION INDUCED BY A 22° FLAP","authors":"C. Cuvier, J. Foucaut, C. Braud, M. Stanislas","doi":"10.1615/tsfp8.1020","DOIUrl":"https://doi.org/10.1615/tsfp8.1020","url":null,"abstract":"","PeriodicalId":206337,"journal":{"name":"Proceeding of Eighth International Symposium on Turbulence and Shear Flow Phenomena","volume":"10 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":"129966858","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":"HIGH-SPEED IMAGING AND PIV MEASUREMENTS IN TURBULENT CAVITATING FLOWS AROUND 2D HYDROFOILS","authors":"A. Kravtsova, D. Markovich, K. Pervunin, M. Timoshevskiy","doi":"10.1615/tsfp8.1570","DOIUrl":"https://doi.org/10.1615/tsfp8.1570","url":null,"abstract":"","PeriodicalId":206337,"journal":{"name":"Proceeding of Eighth 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":"130469811","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":"SECONDARY MOTION IN TURBULENT FLOWS OVER SUPERHYDROPHOBIC SURFACES","authors":"Y. Hasegawa, S. Tuerk, A. Stroh, Getraud Daschiel, B. Frohnapfel","doi":"10.1615/tsfp8.1950","DOIUrl":"https://doi.org/10.1615/tsfp8.1950","url":null,"abstract":"We investigate the effects of superhydrophobic surface carrying streamwise micro grooves on the flow dynamics and the resultant gain in the flow rate in a fully developed turbulent channel flow under a constant pressure gradient. The superhydrophobic surface is modeled as a flat boundary with alternating no-slip and slip conditions, and a series of direct numerical simulations is performed with systematically changing the spanwise periodicity of the streamwise grooves. It is observed that the alternating no-slip and slip boundary conditions cause a spanwise inhomogeneity of the Reynolds shear stress near the superhydrophobic surface, and consequently generate Prandtl’s second kind of secondary flow characterized by coherent streamwise vortices. Accordingly, the instantaneous turbulent flow is decomposed into the spatial-mean, coherent and random components. The detailed turbulent statistics of the three components are obtained and the effect of the secondary flow on the resultant drag reduction is discussed.","PeriodicalId":206337,"journal":{"name":"Proceeding of Eighth 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":"131442427","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":"ON THE ROLE OF INFLOW TURBULENCE FOR MIXING IN A T-JUNCTION","authors":"E. Séverac, Robert Schadwill, Jochen Frohlich","doi":"10.1615/tsfp8.1190","DOIUrl":"https://doi.org/10.1615/tsfp8.1190","url":null,"abstract":"","PeriodicalId":206337,"journal":{"name":"Proceeding of Eighth International Symposium on Turbulence and Shear Flow Phenomena","volume":"42 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":"127645720","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}