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

{"title":"MINIMAL DYNAMICS OF SELF-SUSTAINING ATTACHED EDDIES IN A TURBULENT CHANNEL","authors":"Y. Bengana, Y. Hwang","doi":"10.1615/tsfp9.650","DOIUrl":"https://doi.org/10.1615/tsfp9.650","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":"126492998","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":"STATISTICS AND SCALING OF ADVERSE PRESSURE GRADIENT TURBULENT BOUNDARY LAYERS","authors":"C. Atkinson, V. Kitsios, A-J. Buchner, J. Soria","doi":"10.1615/tsfp9.1060","DOIUrl":"https://doi.org/10.1615/tsfp9.1060","url":null,"abstract":"","PeriodicalId":196124,"journal":{"name":"Proceeding of Ninth International Symposium on Turbulence and Shear Flow Phenomena","volume":"6 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":"130287838","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 EXISTENCE OF NON CLASSICAL DYNAMIC REGIMES IN FRACTAL/MULTISCALE GRID TURBULENCE DECAY","authors":"M. Meldi, H. Lejemble, P. Sagaut","doi":"10.1615/tsfp9.550","DOIUrl":"https://doi.org/10.1615/tsfp9.550","url":null,"abstract":"","PeriodicalId":196124,"journal":{"name":"Proceeding of Ninth International Symposium on Turbulence and Shear Flow Phenomena","volume":"278 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":"133948197","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":"Wall scaling laws for high-Reynolds-number turbulent pipe flow at Reτ = 3008","authors":"Junsun Ahn, Jae Hwa Lee, Jin Lee, H. Sung","doi":"10.1615/tsfp9.1050","DOIUrl":"https://doi.org/10.1615/tsfp9.1050","url":null,"abstract":"","PeriodicalId":196124,"journal":{"name":"Proceeding of Ninth International Symposium on Turbulence and Shear Flow Phenomena","volume":"16 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":"132732914","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-SCALE, COHERENT STRUCTURES IN WIDE-ASPECT-RATIO, TURBULENT, RAYLEIGH-BENARD CONVECTION","authors":"P. Sakievich, Y. Peet, R. Adrian","doi":"10.1615/tsfp9.1000","DOIUrl":"https://doi.org/10.1615/tsfp9.1000","url":null,"abstract":"Investigation of the spatial organization of large-scale, coherent structures in turbulent, Rayleigh-Bénard convection is performed through direct numerical simulation. The simulation is performed in a 6.3 aspect ratio cell with a Rayleigh number of 9.6×107 and Prandtl number equal to 6.7. Single and double point statistics are compared against experimental results and are found to be in excellent agreement. Large-scale mean thermals with coherence times exceeding 10 eddy-turnovers are discovered and these mean thermals are found to be a reliable tool for identifying and interpreting the large, velocity roll-cells. Our simulations show an existence of a large-scale coherent pattern that consists of three major velocity roll-cells, two of which are semi-toroidal, or horse-shoe shaped, that are connected to the side-walls, and the third roll-cell lies across the center of the cell between the semi-toroidal cells. We present the possible formation mechanism of this nearly-periodic structure, observed at intermediate scales of averaging, as a perturbation from a perfectly periodic, crystal-like, pattern. The dynamics of these structures are evaluated using short-time averages.","PeriodicalId":196124,"journal":{"name":"Proceeding of Ninth 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":"114319436","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 STRIPE PATTERN IN POISEUILLE FLOW AT VERY LOW REYNOLDS NUMBER","authors":"K. Fukudome, Y. Ogami","doi":"10.1615/tsfp9.850","DOIUrl":"https://doi.org/10.1615/tsfp9.850","url":null,"abstract":"Direct numerical simulations (DNSs) of a spectral method were performed to study the turbulent structure in a transitional regime in Poiseuille flow. A computational domain tilted towards the streamwise direction was adopted at a high aspect ratio. Though the simulations, turbulent stripes consisting of turbulent and quasilaminar regions were obtained for various values of the angle θ of the stripe with respect to the streamwise direction. The flow rate in the streamwise direction attained a local minimum at θ = 20°, although the flow rate in the spanwise direction attained a maximum at this angle. Moreover, the stripe at θ = 20° became temporally steady for least t < 2800 without lateral spreading. Both the widths and intervals of the turbulent regions are well normalized by the streamwise distance at θ = 10–35°. Furthermore, the width of the turbulent region measured perpendicular to the stripe at θ = 20° is consistent with the highly dissipating region in the homogeneous flow at a very high Reynolds number. INTRODUCTION In the transitional regime, the flow is known to be spatially intermittent, consisting of turbulent and quasilaminar regions. A turbulent stripe is one of the intermittent flow structures in which the turbulent and quasilaminar regions are alternately arrayed in the streamwise and spanwise directions and form a stripe pattern. The turbulent stripe was firstly discovered in the experimental study of Taylor–Couette flow by Coles (1965, 1966). Then, stripes were experimentally observed in a Couette flow by Prigent et al. (2002) and studied numerically by Barkley (2005); similarly, stripes were numerically studied in a Poiseuille flow by Tsukahara et al. (2005, 2007) and experimentally observed (Tsukahara et al., 2010a, Seki et al., 2010, 2012). Additionally, a similar stripe was also found in a torsional Couette flow by Cros et al. (2002). Therefore, turbulent stripes are a common flow state in a flow bounded by parallel walls at the transitional Reynolds number. Further, the turbulent structures of the stripes in various shear flows are common; for instance, the turbulent region evolves many vortical structures, and highand low-speed fluids are distributed upwind and downwind in turbulent regions, respectively. In Poiseuille flow, Iida and Nagano (1998) carried out DNSs of Poiseuille flows in the transitional regime in a small computational domain and found temporal oscillations in the flow rates and friction coefficients. Although they could not capture the turbulent stripe because of their small computational domain, Tsukahara et al. (2005, 2006, 2007) carried out DNSs a large computational domain, captured the stripe structure, and studied the mean structure of the stripes inclined at 21° with respect to the streamwise direction in a very huge computational domain. Duguet et al. (2010) studied the appearance of turbulent stripes in Couette flows and concluded that a stripe was obtained from both a single point disturbance and ","PeriodicalId":196124,"journal":{"name":"Proceeding of Ninth International Symposium on Turbulence and Shear Flow Phenomena","volume":"13 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":"114324707","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":"A NEW AUTONOMIC CLOSURE FOR LARGE EDDY SIMULATIONS","authors":"R. King, P. Hamlington, W. Dahm","doi":"10.1615/tsfp9.100","DOIUrl":"https://doi.org/10.1615/tsfp9.100","url":null,"abstract":"We present a fundamentally new autonomic subgridscale closure for large eddy simulations (LES) that solves a nonlinear, nonparametric system identification problem instead of using a predefined turbulence model. The autonomic approach expresses the local SGS stress tensor as the most general unknown nonlinear function of the resolvedscale primitive variables at all locations and times using a Volterra series. This series is analogous to a Taylor series expansion in both time and space, and incorporates nonlinear, nonlocal, and nonequilibrium turbulence effects. The series introduces a large number of convolution kernel coefficients that are found by solving an inverse problem to minimize the error in representing known subgrid-scale stresses at a test filter scale. The optimized coefficients are then projected to the LES scale by invoking scale similarity in the inertial range and applying appropriate renormalizations. This new closure approach avoids the need to specify a turbulent constitutive model and instead identifies an optimal model on the fly. Here we present the most general formulation of the new autonomic approach and outline an inverse modeling method for optimizing the coefficients. We then explore truncations of the series expansion and demonstrate the effects of regularization and sampling on the optimal coefficients. Finally, we perform a priori tests of this approach using data from direct numerical simulations of homogeneous isotropic and sheared turbulence. We find substantial improvements over the Dynamic Smagorinsky model, even for a 2nd order time-local truncation of the present closure.","PeriodicalId":196124,"journal":{"name":"Proceeding of Ninth 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":"128249303","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 SURFACE TENSION EFFECTS ON INTERFACE DYNAMICS AND ENERGY TRANSFER IN TURBULENCE","authors":"J. McCaslin, O. Desjardins","doi":"10.1615/tsfp9.1180","DOIUrl":"https://doi.org/10.1615/tsfp9.1180","url":null,"abstract":"The interaction between turbulence and surface tension is studied through direct numerical simulation of a canonical multiphase flow. An initially flat interface is inserted into a triply periodic box of decaying homogeneous isotropic turbulence, simulated for a variety of turbulent Reynolds and Weber numbers on mesh sizes of 5123 and 10243. Unity density and viscosity ratios are used in order to isolate the interaction between fluid inertia and the surface tension force. Interface height correlations and liquid volume fraction variance spectra are used to study the spatial scales of corrugations on the interface. A case with zero surface tension is first considered, yielding a passive interface that moves materially with the fluid. The power spectral density of the liquid volume fraction variance follows a κ−1 scaling, where κ is the wavenumber, which is consistent with dimensionality arguments. In the presence of surface tension, this corrugation spectrum follows a κ−1 scaling for large scales, but then deviates at a length scale wich corresponds to the critical radius. A spectral analysis of liquid volume fraction variance transfer is conducted, shedding light on the role played by surface tension in this process. Results will be used to deduce important ramifications for sub-grid scale models in large-eddy simulations of liquid-gas flows.","PeriodicalId":196124,"journal":{"name":"Proceeding of Ninth International Symposium on Turbulence and Shear Flow Phenomena","volume":"285 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":"133988972","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":"TURBULENCE MODULATION AND INSTABILITY INDUCED BY SURFACTANT ADDITIVES IN BACKWARD-FACING STEP FLOW","authors":"Ryusuke Ii, S. Hara, T. Tsukahara, Y. Kawaguchi","doi":"10.1615/tsfp9.600","DOIUrl":"https://doi.org/10.1615/tsfp9.600","url":null,"abstract":"","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":"132942476","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":"EFFECT OF EXTERNAL TURBULENCE ON A TURBULENT WAKE","authors":"Anikesh Pal, S. Sarkar","doi":"10.1615/tsfp9.180","DOIUrl":"https://doi.org/10.1615/tsfp9.180","url":null,"abstract":"Direct numerical simulations are performed to study the evolution of a Re = 10,000 axisymmetric wake under the influence of unforced external (background) turbulence. The external turbulence has an integral length scale 4 times larger than that of the wake turbulence in contrast to Pal & Sarkar (2015) where this ratio was approximately unity. Entrainment of background turbulence leads to a reduction of the wake defect velocity relative to the undisturbed wake. The reduction is significant even when the initial r.m.s of background turbulence is only 1−3% of the body velocity, whereas a similarly strong reductions in the cases simulated by Pal & Sarkar (2015) required 5− 7% initial turbulence levels. This difference is attributed to external turbulence having a slower decay relative to wake turbulence in the present cases owing to the larger eddy-turnover time.","PeriodicalId":196124,"journal":{"name":"Proceeding of Ninth International Symposium on Turbulence and Shear Flow Phenomena","volume":"84 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":"128914785","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}