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

{"title":"PRELIMINARY ANALYSIS OF PERMEABLE COATINGS FOR TURBULENT DRAG REDUCTION","authors":"N. Abderrahaman, R. García-Mayoral","doi":"10.1615/tsfp9.870","DOIUrl":"https://doi.org/10.1615/tsfp9.870","url":null,"abstract":"This study focuses on permeable coatings as a form of passive flow control. A simplified model is proposed to analyse the qualitative effect of the coating's thickness and permeability on drag reduction. For small permeability, the reduction is linear with the length scale of the streamwise permeability. For larger permeability, a degradation mechanism is investigated that depends critically on the geometric mean of the streamwise and wall-normal permeabilities. For a streamwise-to-wall-normal permeability ratio of order 10-100 the maximum drag reduction is predicted to be 15-25%.","PeriodicalId":196124,"journal":{"name":"Proceeding of Ninth International Symposium on Turbulence and Shear Flow Phenomena","volume":"136 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":"127401245","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":"SEMI-EMPIRICAL TURBULENCE MODELS SUITABLE FOR TRAILING EDGE NOISE PREDICTIONS","authors":"C. Albarracin, C. Doolan","doi":"10.1615/tsfp9.390","DOIUrl":"https://doi.org/10.1615/tsfp9.390","url":null,"abstract":"","PeriodicalId":196124,"journal":{"name":"Proceeding of Ninth International Symposium on Turbulence and Shear Flow Phenomena","volume":"108 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":"133526893","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":"VORTICITY TRANSPORT: THE TRANSFER OF VISCOUS STRESS TO REYNOLDS STRESS IN TURBULENT CHANNEL FLOW","authors":"G. Brown, Myoungkyu Lee, R. Moser","doi":"10.1615/tsfp9.1130","DOIUrl":"https://doi.org/10.1615/tsfp9.1130","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":"134415312","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":"Physics and Control of Wall Turbulence","authors":"John Kim","doi":"10.1007/978-1-4020-5152-2_6","DOIUrl":"https://doi.org/10.1007/978-1-4020-5152-2_6","url":null,"abstract":"","PeriodicalId":196124,"journal":{"name":"Proceeding of Ninth International Symposium on Turbulence and Shear Flow Phenomena","volume":"116 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":"121157108","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 experimental study of the role of core intermittency in equivalent jet noise sources","authors":"T. Ecker, K. Lowe, Wing-Fai Ng","doi":"10.1615/tsfp9.980","DOIUrl":"https://doi.org/10.1615/tsfp9.980","url":null,"abstract":"","PeriodicalId":196124,"journal":{"name":"Proceeding of Ninth International Symposium on Turbulence and Shear Flow Phenomena","volume":"17 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":"128429303","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":"TURBULENT CHEMICAL AND THERMONUCLEAR FLAMES: INTRINSIC INSTABILITY AND ANISOTROPIC TURBULENCE AMPLIFICATION","authors":"A. Poludnenko, B. Taylor","doi":"10.1615/tsfp9.350","DOIUrl":"https://doi.org/10.1615/tsfp9.350","url":null,"abstract":"In our previous study (Poludnenko, 2015), we presented the analysis of the intrinsic stability of high-speed turbulent reacting flows. A systematic survey of a wide range of turbulent intensities and system sizes showed that turbulent flames in the regimes considered are intrinsically unstable even in the absence of the surrounding combustor walls or obstacles, which can support the thermoacoustic feedback. In particular, three effects were observed. 1) The turbulent flame speed, ST, can develop pulsations with the observed peak-to-peak amplitude S max /S min > 10. 2) Unstable burning results in the periodic pressure build-up and the formation of pressure waves or shocks, when ST approaches or exceeds the speed of a Chapman-Jouguet deflagration. 3) Coupling of pressure gradients formed during pulsations with density gradients across the flame leads to the anisotropic amplification of turbulence inside the flame volume and flame acceleration. In this work we extend prior analysis, which relied on a simplified single-step reaction model, by demonstrating existence of the pulsating flame instability in two realistic reactive systems: chemical flames in atmospheric H2-air mixtures and thermonuclear flames in degenerate, relativistic plasmas found in stellar interiors. Finally, we also consider the dependence of the instability on the system size by performing a direct numerical simulation containing 32 billion cells in a domain twice larger than considered by Poludnenko (2015). No significant change in the instability dynamics is observed, though further analysis of this question","PeriodicalId":196124,"journal":{"name":"Proceeding of Ninth International Symposium on Turbulence and Shear Flow Phenomena","volume":"148 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":"116338492","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 ESTIMATION OF VORTEX SHEDDING","authors":"S. Illingworth","doi":"10.1615/tsfp9.890","DOIUrl":"https://doi.org/10.1615/tsfp9.890","url":null,"abstract":"","PeriodicalId":196124,"journal":{"name":"Proceeding of Ninth International Symposium on Turbulence and Shear Flow Phenomena","volume":"104 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":"115760618","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 TURBULENCE MODIFICATION BY TUNED WALL-IMPEDANCE","authors":"C. Scalo, J. Bodart, S. Lele, L. Joly","doi":"10.1615/tsfp9.970","DOIUrl":"https://doi.org/10.1615/tsfp9.970","url":null,"abstract":"","PeriodicalId":196124,"journal":{"name":"Proceeding of Ninth International Symposium on Turbulence and Shear Flow Phenomena","volume":"19 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":"121001891","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":"ANALYSIS OF PRESSURE-STRAIN CORRELATIONS IN A SUPERSONIC PIPE, NOZZLE AND DIFFUSER USING GREEN’S FUNCTIONS","authors":"Somnath Ghosh, R. Friedrich","doi":"10.1615/tsfp9.940","DOIUrl":"https://doi.org/10.1615/tsfp9.940","url":null,"abstract":"Pressure-strain correlations along with the turbulent dissipation rate are important terms that need to be modelled in second-order turbulence closures. In this paper, we provide insights into the pressure-strain correlations in a supersonic pipe, nozzle and diffuser by performing Green’s function analyses based on DNS and LES data. The relative importance of the rapid and slow parts of pressure-strain correlations for the axial, azimuthal and radial pressurestrain correlations is presented and it is demonstrated that properly performed LES replicates the trends found in DNS and may be used to develop models for these correlations. INTRODUCTION DNS studies of supersonic channel flows with isothermal walls (Colemanet al., 1995; Foysiet al., 2004) have revealed that compressibility effects manifest themselves as mean density and temperature variations in the near-wall region. This leads to a reduction of pressure-strain correlations at supersonic Mach numbers and in turn to an increase in Reynolds stress anisotropy (Foysi et al., 2004). These observations were also made in DNS of supersonic pipe flow with isothermal wall (Ghoshet al., 2010). Effects of mean dilatation and extra rates of strain add further complications to supersonic flows and lead to changes in the turbulence structure which cannot be explained only by mean property variations. Such effects were described by Bradshaw (1974) and observed in LES and DNS of canonical supersonic nozzle and diffuser flows where fully developed supersonic pipe flow serves as inflow (Ghosh et al., 2008; Ghosh & Friedrich, 2014). It was observed that the Reynolds stresses decrease dramatically in the nozzle and increase in the diffuser. The pressure-strain correlations were found to play a pivotal role in changing the Reynolds stresses in these flows. Hence, it is important to gain insight into the behaviour of pressure-strain correlations in these flows and an elegant way of doing this is a Green’s function analysis based on DNS data. Foysi et al. (2004) used Green’s function to analyse pressure-strain correlations using supersonic channel flow DNS data and found the contribution of the slow terms to be greater than that of the rapid terms. Ghoshet al. (2010) carried out a similar study in cylindrical coordinates with DNS data of a supersonic pipe flow with isothermal wall. Recently Ghosh & Friedrich (2014) extended the Green’s function analysis to a supersonic nozzle and diffuser with isothermal walls using DNS data. In this paper we analyse LES data of supersonic pipe, nozzle and diffuser flow and compare the results with those obtained with DNS. Such a Green’s function analysis with LES data will enable us to easily gain insight into flows for which only LES is possible. MATHEMATICAL AND COMPUTATIONAL DETAILS We use modified Bessel functions to construct the Green’s functions in cylindrical coordinates. The effect of axial non-periodicity in the nozzle and diffuser is taken care of by using a series ex","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":"126868570","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 DATA ASSIMILATION STUDY FOR THE IDENTIFICATION OF SCALES GOVERNING GRID TURBULENCE DECAY","authors":"V. Mons, J. Chassaing, T. Gomez, P. Sagaut","doi":"10.1615/tsfp9.530","DOIUrl":"https://doi.org/10.1615/tsfp9.530","url":null,"abstract":"The decay of incompressible homogeneous isotropic turbulence (HIT), which can be studied via grid turbulence experiments, is among the most important issue in turbulence theory, since isotropic turbulence is the framework in which the deepest investigations of nonlinear features o f turbulence can be performed. Even though numerous studies have been devoted to HIT since about one century, many questions remain open. Among them, the identification of scales which govern the decay of HIT still deserves further investigations. Although there is consensus that the turbu lent kinetic energyK, after a possible transient relaxation phase, follows an algebraic law, i.e. K(t) ∝ tnK , the question of the dependence of the exponent nK to some specific features of the initial condition has raised some controver sies. However, the most recent works indicate that there is no universal regime and that the decay rate is definitely governed by the details of the initial condition. Indeed, it is generally stated in the literature that the exponent nK is related to the asymptotic large-scale behavior of the longi tudinal velocity correlation functionf (r, t = 0) in physical space, or equivalently, to the asymptotic behavior of the ki netic energy spectrumE(k, t = 0) in spectral space. But it is worth keeping in mind that, due to technological limitations, the exact behavior of the velocity correlation function, or that of the energy spectrum, at scales much larger than the integral scale escapes both experimental and numerical investigation at the present time. Besides, the con cept of large-scale asymptotic behavior is hard to reconcil e with real-life turbulent flows, which are bounded in space and can be observed over finite times only. It is also interesting to note that the Comte-Bellot Corrsin theory, which proves to be effective in predicting the value of the exponentnK , relies on a single length scale which is the integral scale.","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":"131286745","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}