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

{"title":"DROPLET DISTRIBUTION AND TRANSPORT IN A TURBULENT SHEAR FLOW","authors":"A. Bagherpour, A. Holloway","doi":"10.1615/tsfp9.760","DOIUrl":"https://doi.org/10.1615/tsfp9.760","url":null,"abstract":"","PeriodicalId":196124,"journal":{"name":"Proceeding of Ninth International Symposium on Turbulence and Shear Flow Phenomena","volume":"33 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":"125253741","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-PRIORI ANALYSIS OF A LES MODEL FOR SCALAR FLUX BASED ON INTERSCALE ENERGY TRANSFER","authors":"M. Klein, C. Wolff, E. Tangermann","doi":"10.1615/tsfp9.750","DOIUrl":"https://doi.org/10.1615/tsfp9.750","url":null,"abstract":"","PeriodicalId":196124,"journal":{"name":"Proceeding of Ninth International Symposium on Turbulence and Shear Flow Phenomena","volume":"14 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":"114021828","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":"TOWARDS WALL-ADAPTION OF TURBULENCE MODELS WITHIN THE LATTICE BOLTZMANN FRAMEWORK","authors":"P. Nathen, D. Gaudlitz, N. Adams","doi":"10.1615/tsfp9.320","DOIUrl":"https://doi.org/10.1615/tsfp9.320","url":null,"abstract":"This paper presents the development towards wall adaptive explicit filters for the simulation of turbulent wall bounded flows in the framework of the lattice Boltzmann method (LBM). First, we show the effect of different collision models on the characteristics of turbulent flow simulations by employing the Taylor-Green vortex as a numerical testcase. Second, an extension of the approximate deconvolution method (ADM), see Malaspinas & Sagaut (2012), Malaspinas & Sagaut (2011) and Sagaut (2010) for the simulation of wall-bounded turbulent flows is presented. A temporal dissipation relaxation is applied for explicit filtering, in order to suppress filtering in regions, where the flow is resolved and to adapt filtering in underresolved regions in such way, that the energy drain in the scales is physically motivated and consistent with the kinetic theory of turbulence. We apply the extended ADM for the simulation of a turbulent channel flow at Reτ = 180 and Reτ = 395 to demonstrate, that the ADM method of Malaspinas & Sagaut (2011) with selective viscosity filters is strictly dissipative for low-order filters. Hence, especially for wall-bounded flows the application of the proposed adaptive relaxation of the filter can be beneficial. The lattice-Boltzmann method LBM solves a set of kinetic equations in terms of discrete velocity distribution functions fα (t,x) numerically. The discrete Boltzmann equations can be written as fα (t +∆t,x+ cα ∆t) = fα (t,x)+Ωα ( fα (t,x)) (1) where Ωα ( fα (t,x)) is the collision operator, which represents non-linear and viscous effects of the Navier Stokes equations and cα is the discrete velocity set of the lattice applied. Macroscopic moments are reconstructed with a Gauss-Hermite quadrature based on the Hermite Polynomial expansion on a discrete lattice. The first two moments 1daniel.gaudlitz@aer.mw.tum.de 2nikolaus.adams@tum.de of the velocity distribution functions are the conserved moments ρ and the momentum ρu, which read ρ = ∑ α fα , ρu = ∑ α cα fα (2) while the momentum flux is the second-order offequilibrium moment of the velocity distribution functions Π = ∑ α f neq α cα cα (3) In order to reconstruct the macroscopic equations of fluid motion, a Chapman Enskog expansion is used. The interested reader can refer to Chen & Doolen (1998) among others. To close equation (1) the collision term needs to be modeled. One well-known approach is the linearization around small perturbations of the thermodynamic equilibrium. This approach is called the Bhatnagar-Gross-Krook (BGK) ansatz, see He & Luo (1997); Guo et al. (2000); Guo & Shu (2013) or Sukop & Thorne (2006) among others, which represents the collision term as a linear relaxation towards a maxwellian equilibrium Ωα ( fα (t,x)) = fα (t +∆t,x+ cα ∆t)− fα (t,x) =− τ ( fα (t,x)− f eq α (t,x) ) . (4) f eq α (t,x) is a low Mach number truncated MaxwellBoltzmann distribution, which is adjusted in such a way, that equation (3) is fulfilled and mass and momentum are conse","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":"131361635","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":"Characteristics of turbulent core-annular flows in a vertical pipe","authors":"Kiyoung Kim, Haecheon Choi","doi":"10.1615/tsfp9.70","DOIUrl":"https://doi.org/10.1615/tsfp9.70","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":"114406200","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":"Effects of cylinder array height on tracked vortex packets in a turbulent boundary layer","authors":"Y. Tan, E. Longmire","doi":"10.1615/tsfp9.430","DOIUrl":"https://doi.org/10.1615/tsfp9.430","url":null,"abstract":"The effect of obstacle height was investigated for cylindrical arrays embedded within the log region of a turbulent boundary layer with Reτ = 2500. The array spacing was set at 0.6δ to match the most probable spanwise spacing of hairpin packets. An array that extended to the top of the log region (H = 500) strongly amplified the 0.6δ mode throughout the log region with the strongest relative amplification closest to the wall at z = 125. A shorter array with H = 125 affected the flow up to z = 300 such that energy contained in spanwise scales below 0.6δ was decreased and energy in larger spanwise scales was increased. Cross correlation of flying PIV fields suggested that the shorter array enhanced the streamwise alignment of incoming packet structures in contrast to the taller array which shifted incoming packets into spanwise zones midway between the cylinders.","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":"115739088","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":"INTERACTIONS OF TURBULENCE AND SCALARS IN SHEAR-DRIVEN PREMIXED TURBULENT FLAMES USING DNS","authors":"Haiou Wang, E. Hawkes, H. Kolla, Jacqueline H. Chen","doi":"10.1615/tsfp9.330","DOIUrl":"https://doi.org/10.1615/tsfp9.330","url":null,"abstract":"The DNS database of modelling lean H2/air combustion in a temporally evolving premixed slot-jet configuration is employed to investigate turbulence-scalar interactions in turbulent reacting flows. In contrast to previous DNS studies of turbulent premixed flames, a mean shear exists in the flow and drives the generation of small-scale turbulence in the shear layer. The orientations of the flame normal and vorticity are examined. It is found that the flame normal preferentially aligns with the most compressive strain rate of the mean flow and the vorticity preferentially aligns with the most extensive mean strain rate. The former is consistent with the fact that the flame front has a tendency to align with the extensive strain rate, while the latter is related to vortex stretching in turbulent flows. The alignment characteristics of the flame normal, vorticity, and turbulent strain rate field conditioned on various progress variable iso-surfaces are investigated. Their influence on the scalar gradients and the vorticity production reflecting the turbulence-scalar interactions are examined quantitatively. INTRODUCTION Premixed turbulent combustion is commonly encountered in practical combustion devices such as gas turbines, and spark-ignition engines. An improved understanding of the interactions between turbulence and chemistry is of great importance for turbulent combustion modelling as well as design of clean and efficient combustion devices. In the present paper, turbulenceflame interactions are studied by analysing the coupled dynamics of the scalar gradient, strain rate and vorticity. The directional preference of the scalar gradients with respect to the strain rate is of substantial importance for modelling premixed turbulent combustion. Specifically, the so-called scalar-turbulence interaction signified by – ρNc(niSijnj) is a source term in the transport equation for the scalar dissipation rate of the progress variable Nc. In the expression signified by –ρNc(niSijnj), ρ is the density, D is the diffusivity, ni is the flame normal component and Sij is the strain rate tensor defined as Sij = 0.5(∂ui/∂xj+∂uj/∂xi). The strain rate Sij can be characterised by the principal eigenvalues λ1, λ2, and λ3 designated by the convention λ1 ≥ λ2 ≥ λ3, which are determined from the characteristic equation. The corresponding eigenvectors are e1, e2 and e3, respectively. The flame normal n is defined in terms of the progress variable c:","PeriodicalId":196124,"journal":{"name":"Proceeding of Ninth International Symposium on Turbulence and Shear Flow Phenomena","volume":"33 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":"123163531","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":"DRAG REDUCTION IN SPATIALLY DEVELOPING TURBULENT BOUNDARY LAYERS BY BLOWING AT CONSTANT MASS-FLUX","authors":"Y. Kametani, K. Fukagata, R. Örlü, P. Schlatter","doi":"10.1615/tsfp9.60","DOIUrl":"https://doi.org/10.1615/tsfp9.60","url":null,"abstract":"Drag reduction in spatially developing turbulent boundary layer by blowing at constant mass-flux.","PeriodicalId":196124,"journal":{"name":"Proceeding of Ninth International Symposium on Turbulence and Shear Flow Phenomena","volume":"65 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":"124846270","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":"STRONG REAL-FLUID EFFECTS ON TRANSCRITICAL TURBULENT BOUNDARY LAYERS AT SUPERCRITICAL PRESSURES","authors":"S. Kawai","doi":"10.1615/tsfp9.680","DOIUrl":"https://doi.org/10.1615/tsfp9.680","url":null,"abstract":"","PeriodicalId":196124,"journal":{"name":"Proceeding of Ninth International Symposium on Turbulence and Shear Flow Phenomena","volume":"39 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":"128057529","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":"QUANTITATIVE MEASUREMENTS OF ABLATION-PRODUCTS TRANSPORT IN A SUPERSONIC TURBULENT BOUNDARY LAYER USING SIMULTANEOUS PIV AND NAPHTHALENE PLIF","authors":"C. Combs, N. Clemens","doi":"10.1615/tsfp9.950","DOIUrl":"https://doi.org/10.1615/tsfp9.950","url":null,"abstract":"The dispersion of a passive scalar in a Mach 5 turbulent boundary layer is investigated using a lowtemperature sublimating ablator (naphthalene). Twodimensional fields of naphthalene mole fraction and velocity are obtained by using simultaneous particle image velocimetry (PIV) and planar laser-induced fluorescence (PLIF). The images show large-scale naphthalene vapor structures that coincide with regions of relatively low streamwise velocity. Additionally, the covariance of naphthalene mole fraction with velocity indicates that an ejection mechanism is transporting low-momentum, highscalar-concentration fluid away from the wall, resulting in the protrusions of naphthalene vapor evident in the instantaneous PLIF images. Mean profiles of streamwise velocity and naphthalene mole fraction are also presented, with the mean mole fraction profile having the expected shape of a classical scalar boundary layer profile. INTRODUCTION There remains continued interest in the study of ablation owing to the need to develop suitable thermal protection systems (TPS) for spacecraft that undergo planetary entry. Charring ablation experienced during atmospheric entry is a complex process involving heat and mass transfer, and codes that predict it require a number of coupled submodels, each of which requires validation (Smits et al., 2009). For example, Reynolds-averaged Navier-Stokes (RANS) and large-eddy simulation (LES) codes require models of the turbulent transport of ablation products; however, suitable scalar-velocity data under relevant conditions are very rare (Ho et al., 2007). Additioanlly, Stogner et al. (2011) conducted an uncertainty analysis of ablation calculations and concluded that turbulence models are one of the largest contributors to the uncertainty of ablation predictions for re-entry flows. A technique has been under development at The University of Texas at Austin that uses planar laser-induced fluorescence (PLIF) of a low-temperature sublimating ablator (naphthalene) to enable visualization of the ablation products in a hypersonic flow (Lochman, 2010; Buxton et al., 2012; Combs et al., 2014a; Combs et al., 2014b; Combs and Clemens, 2015). Lochman (2010) first used naphthalene PLIF to study the transport of ablation products in a Mach 5 turbulent boundary layer. In his work, the technique provided images of naphthalene vapor in the turbulent boundary layer with excellent signal-to-noise ratio (SNR), visualizing both large and small-scale turbulent structures. However, while some spectroscopic measurements were made, a temperature correction was only applied to the profile of the naphthalene boundary layer to yield a “corrected” profile and the images presented are qualitative visualizations. Additionally, no velocity data was collected. In the work by Buxton et al. (2012), naphthalene PLIF was performed simultaneously with particle image velocimetry (PIV) in a Mach 5 turbulent boundary layer using the same insert design as Lochman, providing ","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":"123745935","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":"SENSOR-BASED ESTIMATION OF THE VELOCITY IN THE HIGHLY MODULATED WAKE OF A WALL-MOUNTED PYRAMID","authors":"Z. Hosseini, R. Martinuzzi, B. R. Noack","doi":"10.1615/tsfp9.1150","DOIUrl":"https://doi.org/10.1615/tsfp9.1150","url":null,"abstract":"","PeriodicalId":196124,"journal":{"name":"Proceeding of Ninth International Symposium on Turbulence and Shear Flow Phenomena","volume":"163 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":"122283209","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}