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

{"title":"ALTERNATIVE STRATEGIES FOR MODELLING FLOW OVER IN-LINE TUBE BANKS","authors":"H. Iacovides, B. Launder, D. Laurence, A. West","doi":"10.1615/tsfp8.620","DOIUrl":"https://doi.org/10.1615/tsfp8.620","url":null,"abstract":"This paper reports alternative strategies for modelling turbulent flow and heat transfer around in-line tube banks. The suitability and accuracy of wall-resolved Large Eddy Simulation (LES) and Unsteady Reynolds-Averaged Navier Stokes (URANS) approaches are examined on generic square in-line tube banks, where experimental data are limited but available. Within the latter approach, both eddy-viscosity and Reynolds stress models have been tested. The assumption of flow periodicity in all three directions is investigated by varying the domain size.","PeriodicalId":206337,"journal":{"name":"Proceeding of Eighth International Symposium on Turbulence and Shear Flow Phenomena","volume":"64 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121700943","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":"APPLICATION OF URANS TURBULENCE CLOSURE MODELS TO COMPLEX FLOWS SUBJECTED TO ELECTROMAGNETIC AND OTHER BODY FORCES","authors":"Dean Wilson, T. Craft, H. Iacovides","doi":"10.1615/tsfp8.1230","DOIUrl":"https://doi.org/10.1615/tsfp8.1230","url":null,"abstract":"This paper considers the application of the UnsteadyReynolds Averaged Navier-Stokes (URANS) approach totwo types of electromagnetically influenced turbulent flows.The first is a periodic 2D channel flow with an imposedwall normal magnetic field (Hartmann flow) and the second is that of Rayleigh-B�enard convection with a vertical magnetic field imposed. The turbulence is represented by a low-Re k ?e model which is tested with and without electromagnetic modifications proposed by Kenjere?s & Hanjali�c (2000). The results show the modifications lead to a dramatic reorganisation of the coherent structures in Rayleigh-B�enard convection as the magnetic field strength is increased, but over-predict the damping of the turbulent shear stress in a simple channel flow.","PeriodicalId":206337,"journal":{"name":"Proceeding of Eighth International Symposium on Turbulence and Shear Flow Phenomena","volume":"24 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126630569","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":"MULTI-PHASE BLOOD FLOW MODELLING IN AN INTRACRANIAL ANEURYSM CONSIDERING POSSIBLE TRANSITION TO TURBULENCE","authors":"P. Berg, A. Abdelsamie, Hai Yu, G. Janiga, D. Thévenin","doi":"10.1115/SBC2013-14240","DOIUrl":"https://doi.org/10.1115/SBC2013-14240","url":null,"abstract":"According to the Dorland Medical Dictionary a cerebral aneurysm is an abnormal bulge or ballooning in a blood vessel supplying the brain. Aneurysms can rupture and bleed into the area between the brain and the surrounding membrane. A noticeable percentage of the human population, typically 2 to 5% depending on the country, harbors a cerebral aneurysm, but only about 0.1% of those aneurysms rupture annually [1].Copyright © 2013 by ASME","PeriodicalId":206337,"journal":{"name":"Proceeding of Eighth International Symposium on Turbulence and Shear Flow Phenomena","volume":"50 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128737272","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":"REYNOLDS-NUMBER SCALING OF TURBULENT CHANNEL FLOW","authors":"M. Schultz, K. Flack","doi":"10.1063/1.4791606","DOIUrl":"https://doi.org/10.1063/1.4791606","url":null,"abstract":"Results of an experimental study of smooth-wall, fully developed, turbulent channel flow are presented. The Reynolds number (Rem) based on the channel height and the bulk mean velocity ranged from 10 000 to 300 000. The present results indicate that the skin-friction coefficient (Cf) closely follows a power law for Rem < 62 000. At higher Reynolds numbers, Cf is best described by a log law. Detailed two-component velocity measurements taken at friction Reynolds numbers of Reτ = 1000–6000 indicate that the mean flow and Reynolds shear stress display little or no Reynolds-number dependence. The streamwise Reynolds normal stress (u′2¯+), on the other hand, varies significantly with Reynolds number. The inner peak in u′2¯+ is observed to grow with Reynolds number. Growth in u′2¯+ farther from the wall is documented over the entire range of Reynolds number giving rise to a plateau in the streamwise Reynolds normal stress in the overlap region of the profile for Reτ = 6000. The wall-normal Reynolds normal stres...","PeriodicalId":206337,"journal":{"name":"Proceeding of Eighth International Symposium on Turbulence and Shear Flow Phenomena","volume":"196 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-02-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131757707","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":"TRUE SOURCES OF LINEAR SOUND IN PLANE COUETTE FLOW","authors":"Janice Hau, G. Chagelishvili, G. Khujadze, M. Oberlack, A. Tevzadze","doi":"10.1615/tsfp8.1430","DOIUrl":"https://doi.org/10.1615/tsfp8.1430","url":null,"abstract":"The sound generation by pure vortex mode disturbances in an two-dimensional (2D) unbounded inviscid plane Couette flow is investigated. We present results by Kelvin-mode analysis as well as numerical simulations of the Euler equations, while focusing on the dynamics in the spectral plane. Our results show a dominance of the anisotropic linear sound generation in subsonic shear flows by vortices inside the boundaries of rapid distortion theory (RDT). The linearly generated, highly directional field is comparable to the hydrodynamic field, which physical headstone is the mode coupling, induced by the nonnormality in shear flow systems at moderate shear rates of the velocity. Comparisons of the classical acoustic analogy (AA) approach by Lighthill (1952) with the herein presented results identify the inability of AAs to capture the shear-induced anisotropy of the generated waves in the spectral plane.","PeriodicalId":206337,"journal":{"name":"Proceeding of Eighth International Symposium on Turbulence and Shear Flow Phenomena","volume":"25 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-02-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116354854","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 TURBULENT WAKE OF A SUBMARINE MODEL IN PITCH AND YAW","authors":"A. Ashok","doi":"10.2514/6.2013-1121","DOIUrl":"https://doi.org/10.2514/6.2013-1121","url":null,"abstract":"Introduction We aim to improve our understanding of the high Reynolds number wakes formed by maneuvering submarines. When the submarine is pitched or yawed, a complex, three-dimensional separation occurs over the body which results in a non-axisymmetric wake. Studies on wakes have typically been confined to planar or axisymmetric wakes generated by disks, spheres, and other bodies-of-revolution (see, for example, Johannsson and George (2006) and Jimenez et al. (2010)). In contrast, the downstream development of the nonaxisymmetric wake has been much less well studied. Lloyd and Campbell (1986), in a study of submarine wakes noted that the azimuthual adverse pressure gradient on a pitched, body-of-revolution causes boundary layer separation, and the separated shear layers then roll up in to streamwise vortices, which increase in strength as more fluid is entrained into the vortex cores until they are shed into the wake with a fixed circulation (see Figure 1). They found that at high angles of incidence asymmetric vortex patterns may be visible but that these angles of incidence are not generally encountered by submarines. As we shall see, such asymmetric wake patterns appear to be characteristic of pitched or yawed bodies of revolution at sufficiently high Reynolds number even at lower angles which may well be encountered by maneuvering submarines. In another important study, Chesnakas and Simpson (1997) investigated the three-dimensional flow","PeriodicalId":206337,"journal":{"name":"Proceeding of Eighth International Symposium on Turbulence and Shear Flow Phenomena","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-01-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130011598","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 WALL-BOUNDED TURBULENCE OVER REGULARLY DISTRIBUTED ROUGHNESS","authors":"M. Placidi, B. Ganapathisubramani","doi":"10.1615/tsfp8.1820","DOIUrl":"https://doi.org/10.1615/tsfp8.1820","url":null,"abstract":"Experiments were conducted in the fully-rough regime on surfaces consisting of regularly distributed Lego bricks of uniform height, arranged in different configurations. Measurements were made with high resolution planar Particle Image Velocimetry on six different configurations at different frontal solidity, λF , and fixed plan solidity, λP. Results indicate that mean velocity profiles in defect form conforms to outer-layer similarity. However, streamwise, wall-normal turbulent intensities and particularly Reynolds shear stresses show a lack of similarity across the different cases. Quadrant analysis reveals an increase in Q4 and in Q2 activities in the outer layer which is dependent on the frontal solidity. Proper Orthogonal Decomposition show an increase in fractional and cumulative turbulent kinetic energy contribution of the lowest-order modes with increasing the density of the elements, indicating a redistribution of the energy toward the larger-scales.","PeriodicalId":206337,"journal":{"name":"Proceeding of Eighth International Symposium on Turbulence and Shear Flow Phenomena","volume":"128 5","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-11-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132801177","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":"DYNAMIC MODE DECOMPOSITION OF PIV MEASUREMENTS FOR CYLINDER WAKE FLOW IN TURBULENT REGIME","authors":"L. Cordier, G. Tissot, N. Benard, B. R. Noack","doi":"10.1615/tsfp8.2010","DOIUrl":"https://doi.org/10.1615/tsfp8.2010","url":null,"abstract":"Dynamic Mode Decomposition (DMD) is a new post-processing technique that can extract from snapshots dynamic informations relevant for the flow. Without explicit knowledge of the dynamical operator, the DMD algorithm determines eigenvalues and eigenvectors of an approximate linear model. DMD can be viewed as a non linear generalization of global stability classically used for a linearized system. This algorithm can be used to determine the eigen-elements of the Koopman operator, an infinite dimensional linear operator associated with the nonlinear system. The ability of DMD to extract dynamically relevant features of the flow has been tested on an experimental PIV dataset of a turbulent cylinder wake flow.","PeriodicalId":206337,"journal":{"name":"Proceeding of Eighth International Symposium on Turbulence and Shear Flow Phenomena","volume":"59 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-11-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131333258","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":"AERODYNAMIC CONTROL OF A PITCHING AIRFOIL USING DISTRIBUTED ACTIVE BLEED","authors":"John M. Kearney, A. Glezer","doi":"10.1615/tsfp8.1540","DOIUrl":"https://doi.org/10.1615/tsfp8.1540","url":null,"abstract":"","PeriodicalId":206337,"journal":{"name":"Proceeding of Eighth International Symposium on Turbulence and Shear Flow Phenomena","volume":"355 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123337669","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":"INVERSE MAGNUS EFFECT ON A ROTATING SPHERE","authors":"Jooha Kim, Hyungmin Park, Haecheon Choi, J. Yoo","doi":"10.1615/tsfp8.1440","DOIUrl":"https://doi.org/10.1615/tsfp8.1440","url":null,"abstract":"For a rotating sphere or cylinder, the lift coefficients become negative at some specific Reynolds numbers Re and spin ratios α (ratio of surface velocity to the free-stream velocity), called inverse Magnus effect. In the present study, the inverse Magnus effect on a rotating sphere is experimentally investigated at Re= 0.6×105−1.8×105, based on the free-stream velocity U0 and sphere diameter d. By varying the spin ratio from 0 (no spin) to 1.7, we measure the lift, drag, and velocity field behind the rotating sphere. At a given Re, the lift force is positive, negative and then positive again with increasing spin ratio. At higher Reynolds number, the rapid decrease of the lift coefficient occurs at lower spin ratio and thus the negative lift (i.e. inverse Magnus effect) starts to appear at lower spin ratio. The velocity field measured from a particle image velocimetry (PIV) indicates that the inverse Magnus effect results from the differences in the boundary-layer growth and separation along the retreating and advancing sphere surfaces: i.e., the main separation is delayed more on the advancing side than on the retreating side. The radius of curvature of streamlines on the advancing side becomes smaller than that on the retreating side, resulting in lower pressure on the advancing side. As a result, the lift force becomes negative with the wake deflected from advancing to retreating side. INTRODUCTION Flow over a rotating sphere is of a significant interest in many sports such as golf, baseball, tennis, table tennis, soccer, and volleyball, because all the balls used in these sports translate and rotate simultaneously. For a clockwiserotating sphere moving from right to left, it is well known that the lift exerts an upward force, which is called the Magnus effect (Magnus, 1853). However, at some specific Reynolds numbers and spin ratios, the lift exerts in the opposite direction to the Magnus force, which is called the inverse (or negative) Magnus effect. Although several studies have experimentally measured the negative lift on a rotating sphere (Maccoll, 1928; Davies, 1949; Taneda, 1957; Briggs, 1959; Tanaka et al., 1990; Aoki et al., 2003a,b; Barlow & Domanski, 2008; Kray et al., 2012), no quantitative velocity measurement has been performed to understand this phenomenon. Therefore, in the present study, we experimentally investigate the mechanism of the inverse Magnus effect on a rotating sphere through direct measurements of drag and lift forces and measurement of velocity using a PIV. 1 August 28 30, 2013 Poitiers, France AER2D Motor (N = 0 ~ 1300 rpm)","PeriodicalId":206337,"journal":{"name":"Proceeding of Eighth International Symposium on Turbulence and Shear Flow Phenomena","volume":"17 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123494841","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}