Relevant bibliographies by topics / Lagrangian Statistical Method

Academic literature on the topic 'Lagrangian Statistical Method'

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Published: 10 December 2022
Last updated: 28 January 2023

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Journal articles on the topic "Lagrangian Statistical Method"

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Li, Jiaojiao, Shanzhou Niu, Jing Huang, Zhaoying Bian, Qianjin Feng, Gaohang Yu, Zhengrong Liang, Wufan Chen, and Jianhua Ma. "An Efficient Augmented Lagrangian Method for Statistical X-Ray CT Image Reconstruction." PLOS ONE 10, no. 10 (October 23, 2015): e0140579. http://dx.doi.org/10.1371/journal.pone.0140579.

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Grosshans, H., R. ‐Z Szász, and L. Fuchs. "Development of an efficient statistical volumes of fluid–Lagrangian particle tracking coupling method." International Journal for Numerical Methods in Fluids 74, no. 12 (February 4, 2014): 898–918. http://dx.doi.org/10.1002/fld.3879.

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WANG, Y. J., N. ZHAO, C. W. WANG, and D. H. WANG. "A SECOND-ORDER ADAPTIVE ARBITRARY LAGRANGIAN–EULERIAN METHOD FOR THE COMPRESSIBLE EULER EQUATIONS." Modern Physics Letters B 23, no. 04 (February 10, 2009): 583–601. http://dx.doi.org/10.1142/s0217984909017923.

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Most of finite volume schemes in the Arbitrary Lagrangian–Eulerian (ALE) method are constructed on the staggered mesh, where the momentum is defined at the nodes and the other variables (density, pressure and specific internal energy) are cell-centered. However, this kind of schemes must use a cell-centered remapping algorithm twice which is very inefficient. Furthermore, there is inconsistent treatment of the kinetic and internal energies.1 Recently, a new class of cell-centered Lagrangian scheme for two-dimensional compressible flow problems has been proposed in Ref. 2. The main new feature of the algorithm is the introduction of four pressures on each edge, two for each node on each side of the edge. This scheme is only first-order accurate. In this paper, a second-order cell-centered conservative ENO Lagrangian scheme is constructed by using an ENO-type approach to extend the spatial second-order accuracy. Time discretization is based on a second-order Runge–Kutta scheme. Combining a conservative interpolation (remapping) method3,4 with the second-order Lagrangian scheme, a kind of cell-centered second-order ALE methods can be obtained. Some numerical experiments are made with this method. All results show that our method is effective and have second-order accuracy. At last, in order to further increase the resolution of shock regions, we use an adaptive mesh generation based on the variational principle5 as a rezoned strategy for developing a class of adaptive ALE methods. Numerical experiments are also presented to valid the performance of the proposed method.
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CHEN, DI-JIA, KUN-HAO LIN, and CHAO-AN LIN. "IMMERSED BOUNDARY METHOD BASED LATTICE BOLTZMANN METHOD TO SIMULATE 2D AND 3D COMPLEX GEOMETRY FLOWS." International Journal of Modern Physics C 18, no. 04 (April 2007): 585–94. http://dx.doi.org/10.1142/s0129183107010826.

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In this paper, the lattice Boltzmann method is combined with the immersed boundary technique to simulate complex geometry flows. The complex geometry is represented by Lagrangian markers and forces are exerted at the Lagrangian markers in order to satisfy the prescribed velocity of the boundary. This force at the Lagrangian markers is then distributed to the Eulerian grid by a well-chosen discretized delta function. With the known force field in the Eulerian grid to mimic the boundary, the lattice Boltzmann method is used to compute the flow field where the complex geometry is immersed inside the Cartesian computational domain. Numerical experiments show that the second-order accuracy of the adopted numerical scheme is degraded to 1.8 order. The proposed method is examined by computing decaying vortex, lid driven cavity flow and 2D and 3D flows over asymmetrically placed cylinder. All the numerical results are compatible with the benchmark solutions.
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Fan, Xiaofeng, Jiangfeng Wang, Faming Zhao, Jiawei Li, and Tianpeng Yang. "Eulerian–Lagrangian method for liquid jet atomization in supersonic crossflow using statistical injection model." Advances in Mechanical Engineering 10, no. 2 (February 2018): 168781401876129. http://dx.doi.org/10.1177/1687814018761295.

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Sigmond, M., J. Meloen, and P. C. Siegmund. "Stratosphere-troposphere exchange in an extratropical cyclone, calculated with a Lagrangian method." Annales Geophysicae 18, no. 5 (May 31, 2000): 573–82. http://dx.doi.org/10.1007/s00585-000-0573-1.

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Abstract. A Lagrangian technique is developed and applied to calculate stratosphere-troposphere exchange in an extratropical cyclone. This exchange is computed from the potential vorticity or PV along trajectories, calculated from ECMWF circulation data. Special emphasis is put on the statistical significance of the results. The computed field of the cross-tropopause flux is dominated by elongated patterns of statistically significant large downward and small upward fluxes. The downward fluxes mainly occur in the lower part of the considered tropopause folds. The upward fluxes are found near the entrance of the folds, in the tropopause ridges. The ratio between the area averaged downward and upward cross-tropopause fluxes increases with increasing strength of the cyclone. Since the largest fluxes are shown to occur in the regions with the largest wind shear, where PV-mixing is thought to cause large cross-tropopause fluxes, the results are expected to be reliable, at least in a qualitative sense. The position of a tropopause fold along the northwest coast of Africa is confirmed by total ozone observations. The results indicate that the applied Lagrangian technique is an appropriate tool for diagnosing stratosphere-troposphere exchange.Key words: Meteorology and atmospheric dynamics (general circulation; mesoscale meteorology; middle atmosphere dynamics)
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Abarbanel, Henry D. I., Paul J. Rozdeba, and Sasha Shirman. "Machine Learning: Deepest Learning as Statistical Data Assimilation Problems." Neural Computation 30, no. 8 (August 2018): 2025–55. http://dx.doi.org/10.1162/neco_a_01094.

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We formulate an equivalence between machine learning and the formulation of statistical data assimilation as used widely in physical and biological sciences. The correspondence is that layer number in a feedforward artificial network setting is the analog of time in the data assimilation setting. This connection has been noted in the machine learning literature. We add a perspective that expands on how methods from statistical physics and aspects of Lagrangian and Hamiltonian dynamics play a role in how networks can be trained and designed. Within the discussion of this equivalence, we show that adding more layers (making the network deeper) is analogous to adding temporal resolution in a data assimilation framework. Extending this equivalence to recurrent networks is also discussed. We explore how one can find a candidate for the global minimum of the cost functions in the machine learning context using a method from data assimilation. Calculations on simple models from both sides of the equivalence are reported. Also discussed is a framework in which the time or layer label is taken to be continuous, providing a differential equation, the Euler-Lagrange equation and its boundary conditions, as a necessary condition for a minimum of the cost function. This shows that the problem being solved is a two-point boundary value problem familiar in the discussion of variational methods. The use of continuous layers is denoted “deepest learning.” These problems respect a symplectic symmetry in continuous layer phase space. Both Lagrangian versions and Hamiltonian versions of these problems are presented. Their well-studied implementation in a discrete time/layer, while respecting the symplectic structure, is addressed. The Hamiltonian version provides a direct rationale for backpropagation as a solution method for a certain two-point boundary value problem.
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Wang, Han, and Oliver Bühler. "Anisotropic Statistics of Lagrangian Structure Functions and Helmholtz Decomposition." Journal of Physical Oceanography 51, no. 5 (May 2021): 1375–93. http://dx.doi.org/10.1175/jpo-d-20-0199.1.

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AbstractWe present a new method to estimate second-order horizontal velocity structure functions, as well as their Helmholtz decomposition into rotational and divergent components, from sparse data collected along Lagrangian observations. The novelty compared to existing methods is that we allow for anisotropic statistics in the velocity field and also in the collection of the Lagrangian data. Specifically, we assume only stationarity and spatial homogeneity of the data and that the cross covariance between the rotational and divergent flow components is either zero or a function of the separation distance only. No further assumptions are made and the anisotropy of the underlying flow components can be arbitrarily strong. We demonstrate our new method by testing it against synthetic data and applying it to the Lagrangian Submesoscale Experiment (LASER) dataset. We also identify an improved statistical angle-weighting technique that generally increases the accuracy of structure function estimations in the presence of anisotropy.
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WANG, DONGHONG, NING ZHAO, and YONGJIAN WANG. "A CELL-CENTERED LAGRANGIAN SCHEME FOR COMPRESSIBLE MULTI-MEDIUM FLOW." Modern Physics Letters B 24, no. 13 (May 30, 2010): 1283–86. http://dx.doi.org/10.1142/s0217984910023438.

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In this paper, a kind of Godunov-type Lagrangian scheme is developed in the one space dimension. The Riemann problems are constructed at the interface and the velocity and pressure are evaluated using an implicit characteristic method. Two different methods are used to solve for the equation of energy conservation. Four one-dimensional numerical examples are first presented to obtain the parameter through comparison of the L1 errors with the changing parameter values. The method having the minimal error is then extended to two dimensions and a cell-centered conservative Lagrangian scheme is proposed for the compressible multi-medium flow. The numerical results for some classical two dimensional hydrodynamic test cases show that the proposed numerical methods are effective and feasible.
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CHEN, HONGQUAN, and LING RAO. "THE TECHNIQUE OF THE IMMERSED BOUNDARY METHOD: APPLICATIONS TO THE NUMERICAL SOLUTIONS OF IMCOMPRESSIBLE FLOWS AND WAVE SCATTERING." Modern Physics Letters B 23, no. 03 (January 30, 2009): 437–40. http://dx.doi.org/10.1142/s021798490901859x.

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A fictitious domain method, in which the Dirichlet boundary conditions are treated using boundary supported Lagrangian multipliers, is considered. The technique of the immersed boundary method is incorporated into the framework of the fictitious domain method. Contrary to conventional methods, it does not make use of the finite element discretization. It has a simpler structure and is easily programmable. The numerical simulation of two-dimensional incompressible inviscid uniform flows over a circular cylinder validates the methodology and the numerical procedure. The numerical simulation of propagation phenomena for time harmonic electromagnetic waves by methods combining controllability and fictitious domain techniques is also presented. Using distributed Lagrangian multipliers, the propagation of the wave can be simulated on an obstacle free computational region with regular finite element meshes essentially independent of the geometry of the obstacle and by a controllability formulation which leads to algorithms with good convergence properties for time-periodic solutions. The numerical results presented are in good agreement with those in the literature using obstacle fitted meshes.
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Dissertations / Theses on the topic "Lagrangian Statistical Method"

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Marnitz, Philipp. "Statistische Multiresolutions-Schätzer in linearen inversen Problemen - Grundlagen und algorithmische Aspekte." Doctoral thesis, 2010. http://hdl.handle.net/11858/00-1735-0000-0006-B6A2-8.

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Bhatnagar, Akshay. "Direct Numerical Simulations of Fluid Turbulence : (A) Statistical Properties of Tracer And Inertial Particles (B) Cauchy-Lagrange Studies of The Three Dimensional Euler Equation." Thesis, 2016. http://hdl.handle.net/2005/2747.

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The studies of particles advected by tubulent flows is an active area of research across many streams of sciences and engineering, which include astrophysics, fluid mechanics, statistical physics, nonlinear dynamics, and also chemistry and biology. Advances in experimental techniques and high performance computing have made it possible to investigate the properties these particles advected by fluid flows at very high Reynolds numbers. The main focus of this thesis is to study the statistics of Lagrangian tracers and heavy inertial particles in hydrodynamic and magnetohydrodynamic (MHD) turbulent flows by using direct numerical simulations (DNSs). We also study the statistics of particles in model stochastic flows; and we compare our results for such models with those that we obtain from DNSs of hydrodynamic equations. We uncover some of aspects of the statistical properties of particle trajectories that have not been looked at so far. In the last part of the thesis we present some results that we have obtained by solving the three-dimensional Euler equation by using a new method based on the Cauchy-Lagrange formulation. This thesis is divided into 6 chapters. Chapter 1 contains an introduction to the background material that is required for this thesis; it also contains an outline of the problems we study in subsequent Chapters. Chapter 2 contains our study of “Persistence and first-passage time problems with particles in three-dimensional, homogeneous, and isotropic turbulence”. Chapter 3 is devoted to our study of “Universal Statistical Properties of Inertial-particle Trajectories in Three-dimensional, Homogeneous, Isotropic, Fluid Turbulence”. Chapter 4 deals with “Time irreversibility of Inertial-particle trajectories in Homogeneous, Isotropic, Fluid Turbulence”. Chapter 5 contains our study of the “Statistics of charged inertial particles in three-dimensional magnetohydrodynamic (MHD) turbulence”. Chapter 6 is devoted to our study of “The Cauchy-Lagrange method for the numerical integration of the threedimensional Euler equation”.
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Mullan, Sean. "Tidal sedimentology and geomorphology in the central Salish Sea straits, British Columbia and Washington State." Thesis, 2017. https://dspace.library.uvic.ca//handle/1828/8943.

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Intra-archipelago waterways, including tidal strait networks, present a complex set of barriers to, and conduits for sediment transport between marine basins. Tidal straits may also be the least well understood tide-dominated sedimentary environment. To address these issues, currents, sediment transport pathways, and seabed sedimentology & geomorphology were studied in the central Salish Sea (Gulf and San Juan Islands region) of British Columbia, Canada and Washington State, USA. A variety of data types were integrated: 3D & 2D tidal models, multibeam bathymetry & backscatter, seabed video, grab samples, cores and seismic reflection. This dissertation included the first regional sediment transport modelling study of the central Salish Sea. Lagrangian particle dispersal simulations were driven by 2D tidal hydrodynamics (~59-days). It was found that flood-tide dominance through narrow intra-archipelago connecting straits resulted in the transfer of sediment into the inland Strait of Georgia, an apparent sediment sink. The formative/maintenance processes at a variety of seabed landforms, including a banner bank with giant dunes, were explained with modelled tides and sediment transport. Deglacial history and modern lateral sedimentological and morphological transitions were also considered. Based on this modern environment, adjustments to the tidal strait facies model were identified. In addition, erosion and deposition patterns across the banner bank (dune complex) were monitored with 8-repeat multibeam sonar surveys (~10 years). With these data, spatially variable bathymetric change detection techniques were explored: A) a cell-by-cell probabilistic depth uncertainty-based threshold (t-test); and B) coherent clusters of change pixels identified with the local Moran's Ii spatial autocorrelation statistic. Uncertainty about volumetric change is a considerable challenge in seabed change research, compared to terrestrial studies. Consideration of volumetric change confidence intervals tempers interpretations and communicates metadata. Techniques A & B may both be used to restrict volumetric change calculations in area, to exclude low relative bathymetric change signal areas.
Graduate
2018-12-07
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Book chapters on the topic "Lagrangian Statistical Method"

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Frisch, U., A. Mazzino, A. Noullez, and M. Vergassola. "Lagrangian Method for Multiple Correlations in Passive Scalar Advection." In IUTAM Symposium on Geometry and Statistics of Turbulence, 153–73. Dordrecht: Springer Netherlands, 2001. http://dx.doi.org/10.1007/978-94-015-9638-1_19.

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Mezzan, Youness, and Moulay Hicham Tber. "A Lagrangian Mixed Finite Elements Method for Advection-Diffusion Equations." In Springer Proceedings in Mathematics & Statistics, 99–105. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-83442-5_8.

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Soomere, Tarmo. "Statistics of Lagrangian Transport Reveals Hidden Features of Velocity Fields." In Preventive Methods for Coastal Protection, 283–318. Heidelberg: Springer International Publishing, 2013. http://dx.doi.org/10.1007/978-3-319-00440-2_9.

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Zhao, Xin-Yuan, Tao Cai, and Dachuan Xu. "A Newton-CG Augmented Lagrangian Method for Convex Quadratically Constrained Quadratic Semidefinite Programs." In Springer Proceedings in Mathematics & Statistics, 337–45. Cham: Springer International Publishing, 2014. http://dx.doi.org/10.1007/978-3-319-08377-3_33.

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Cheng, Hanz Martin, and Jérôme Droniou. "Combining the Hybrid Mimetic Mixed Method and the Eulerian Lagrangian Localised Adjoint Method for Approximating Miscible Flows in Porous Media." In Springer Proceedings in Mathematics & Statistics, 367–76. Cham: Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-57394-6_39.

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Mussardo, Giuseppe. "Particle Spectrum by Semi-classical Methods." In Statistical Field Theory, 882–912. Oxford University Press, 2020. http://dx.doi.org/10.1093/oso/9780198788102.003.0023.

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Chapter 23 discusses the setting of a semi-classical method—based on the Lagrangian density of the model, irrespective of whether or not it describes an integrable system—to address the computation of the particle spectrum of bound states in quantum field theory with a set of degenerate vacua connected by kink excitations. It begins by investigating kinks and anti-kinks and a semi-classical formula for the kink matrix elements, as well as asymptotic behavior. It then goes on to cover such topics as universal mass formula, symmetric wells, asymmetric wells and the double Sine–Gordon model, a benchmark of the semi-classical method.
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Conference papers on the topic "Lagrangian Statistical Method"

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Kampanas, Vasileios, Maxwell Williams, and Andrew Garmory. "Characterising Mixing and Soot Production Using a Lagrangian Statistical Method." In ASME Turbo Expo 2020: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/gt2020-15125.

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Abstract An understanding of fuel-air mixing, along with the link between turbulent fluid flows and soot production is vital for the design of an efficient, low emissions gas turbine combustor. This paper uses a Lagrangian statistical method to investigate the time histories of mixing hence and soot development for massless parcels tracked within an LES calculation. This provides the advantage of investigating soot development using an inexpensive post-processing technique. The method comprises tracking massless parcels through the flow and recording the local temperature and composition at the parcel location, as well as the age of the parcel. This can be used to give statistical information about various aspects of mixing and soot production, such as distributions of mixture fraction or residence times. The history for each parcel can then be used in a postprocessing step to predict the soot development in time for that parcel path. This has been used to compare Large Eddy Simulations (LES) of reacting flows in both a laboratory aero-engine model combustor and a geometry representative of an annular sector from an aircraft engine combustor. It was found, that when normalized by a reference time scale based on combustor length and bulk velocity, the residence times for the annular sector were considerably shorter and mixture fraction distributions wider. This was due to a much higher chance of parcels being recirculated within the primary zone of the laboratory combustor. Further analysis of the annular combustor sector showed that very different mixing is found between the oxidation ports on the centre of the sector compared to those at the edge. The instantaneous mixing is seen to be less effective for those ports at the edge of the sector and this leads to higher soot levels in these regions.
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Mor, M., and A. Wolf. "Rigid-Body Motion Estimation Using Statistical Solid Dynamics Method and Dynamic Method." In ASME 2008 9th Biennial Conference on Engineering Systems Design and Analysis. ASMEDC, 2008. http://dx.doi.org/10.1115/esda2008-59365.

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The most frequently used method in three dimensional human gait analysis involves placing markers on the skin of the analyzed segment. This introduces a significant artifact which strongly influences the bone position and orientation and joint kinematics estimates. The benefit in developing a method to reduce soft tissue artifacts is significant, resulting in the prevention, better diagnosis, and treatment of joint disorders and in the design of better prosthetic devices with longer mean times to failure. In this work we approached the problem of soft tissue artifacts from both a dynamic method and a statistical solid dynamics method. The dynamic method is based on the implementation of a Lagrangian approach to drive model based procedure for the estimation of the rigid body (bone) motion for the measurements of markers attached to the skin. The statistical solid dynamics method is a combination of several existent tools. It is based on a least squares optimization of markers position and orientation. Both methods were tested and evaluated using computer simulation and similar dynamics systems.
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Lebas, Romain, Pierre-Arnaud Beau, Gre´gory Blokkeel, and Franc¸ois-Xavier Demoulin. "ELSA Model for Atomization: To Benefit of the Eulerian and Lagrangian Descriptions of the Liquid Phase." In ASME 2006 2nd Joint U.S.-European Fluids Engineering Summer Meeting Collocated With the 14th International Conference on Nuclear Engineering. ASMEDC, 2006. http://dx.doi.org/10.1115/fedsm2006-98167.

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In the context of the Euler-Lagrange Spray Atomization (ELSA) model [1,2,3] for two-phase flows, a Eulerian approach is used to describe the dense part of the spray and it is completed elsewhere by a standard Lagrangian approach. A recurrent issue of the Lagrangian approach is the difficulty to reach a number of stochastic samples large enough, in each mesh cell, to achieve statistical convergence. It is necessary to propose methods that can benefit of the Lagrangian formulation to describe the statistical dispersion but that are converged for certain key quantities like the mass of liquid. Such ideas are already developed under the so-called Direct Quadrature Method Of Moments (DQMOM) [4]. This complex method is not directly used here, a more practical approach that used the usual formalism of Lagrangian methods for spray is proposed. The method will take into account the originally unused Eulerian equation in the diluted part of the spray to transport the key mean quantities of the spray. In each mesh cell that contains Lagrangian stochastic particles the liquid mass fraction can be obtained from the Eulerian equation. Equivalently, in the mesh cell considered, a Lagrangian liquid mass fraction is defined. It is clear that big statistical fluctuations of this variable can be expected if the number of particles in the cell is not high enough. The least noisy Eulerian variable will be used to correct the Lagrangian one. There are numerous possible ways to correct the Lagrangian variable, one method will be presented. In the same manner, the Eulerian equation for the density of liquid surface is used to correct the Sauter mean diameter that can be obtained from the Lagrangian description. Hence, the Lagrangian phase is linked to the Eulerian equations. But the Eulerian equations have to be linked also to the Lagrangian phase, this is achieved through the liquid turbulent diffusion flux closure and through the source terms of surface density transport equation, i.e. those modeling break-up and coalescence effects. By this way, the Lagrangian phase, whenever it is available, enables to take into account the joint probability density functions of fluctuating variables such as droplet diameter or droplet velocities.
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Tufano, Dante A., and Zahra Sotoudeh. "Introducing Entropy for the Statistical Energy Analysis of an Artificially Damped Oscillator." In ASME 2015 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/imece2015-50591.

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The purpose of this paper is to introduce the concept of entropy for a main resonator attached to a “fuzzy structure”. This structure is described explicitly using the Lagrangian method, and is treated as a layer of discrete resonators. A generic entropy formulation is then developed for the layer of resonators, which is used to determine the individual oscillator entropies. The combined entropy of the linear resonator system is then determined and compared numerically to the sum of the individual oscillator entropies. The entropy behavior of the system is then related to the energy behavior of the system and explained in regards to the the “artificial damping” of the main resonator.
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Li, Dongqin, Philip A. Wilson, Yifeng Guan, and Xin Zhao. "An Effective Approximation Modeling Method for Ship Resistance in Multidisciplinary Ship Design Optimization." In ASME 2014 33rd International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/omae2014-23407.

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Ship design is related to several disciplines such as hydrostatic, resistance, propulsion and economic. The traditional ship design process only involves independent design optimization with some regression formulas within each discipline and there is no guarantee to achieve the optimum design. At the same time, it is crucial to improve the efficiency of modern ship design. Nowadays, the methods of computational fluid dynamics (CFD) has been brought into the ship design optimization. However, there are still some problems such as calculation precision and time consumption especially when CFD software is inlaid into the optimization procedure. Modeling is a far-ranging and all-around subject, and its precision directly affects the scientific decision in future. How to establish an accurate approximation model instead of the CFD calculation will be the key problem. The Support Vector Machines (SVM), a new general machine learning method based on the frame of statistical learning theory, may solve the problems in sample space and be an effective method of processing the non-liner classification and regression. The classical SVR has two parameters to control the errors. A new algorithm of Support Vector Regression proposed in this article has only one parameter to control the errors, adds b2/2 to the item of confidence interval at the same time, and adopts the Laplace loss function. It is named Single-parameter Lagrangian Support Vector Regression (SPL-SVR). This effective algorithm can improve the operation speed of program to a certain extent, and has better fitting precision. In practical design of ship, Design of Experiment (DOE) and the proposed support vector regression algorithm are applied to ship design optimization to construct statistical approximation model in this paper. The support vector regression algorithm approximates the optimization model and is updated during the optimization process to improve accuracy. The result indicates that the SPL-SVR method to establish approximate models can effectively solve complex engineering design optimization problem. Finally, some suggestions on the future improvements are proposed.
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Zhuang, Xinwei, and Xiuling Wang. "Environment Analysis Near a Highway Using Computational Fluid Dynamics." In ASME 2014 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/imece2014-38717.

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Air pollution has been proven as a significant risk factor for multiple health conditions. A major portion of urban air pollution is attributed to vehicle emissions. In this study, a high school which is close to an interstate highway is numerical simulated to estimate the impact of traffic emissions on air quality. Two probability density functions, Weibull distribution and Rayleigh distribution, were used in wind data statistical analysis. A numerical method was used to estimate the wind speed at study site based on the wind data in meteorology stations. Both indoor and outdoor environment were simulated using computational fluid dynamics (CFD). The airflow and the dispersion of particulate air pollutants emitted from the highways surrounding the high school building were analyzed. The wind flow was simulated using Reynolds-Averaged Navier Stokes (RANS) model. The particulate matters are tracked using Lagrangian model. For the indoor simulation, the standard k-ε model is employed to model the air-phase turbulence. Discrete phase model (DPM) and Eulerian multiphase model were utilized for the particle phase, respectively. The comparison shows that the Lagrangian approach has better agreement since the dispersed-phase volume fractions are less than 10%.
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He, Pengfei, Raivat Patel, Bo Zhang, and Chao Zhu. "Liquid Attachment and Momentum Transfer by Collisions Between Free-Fall Solids and Liquid Spray Droplets." In ASME 2012 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/imece2012-86628.

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Understanding the solids wetting by collisions between flowing solids and spray droplets is essential to optimizing the design and operation of related industrial processes. This paper presents an innovative experimental method to identify the statistical distributions of liquid attachment and collision probability of the impingement of a liquid spray onto free-fall particles. To separate the liquid attachment from other contributions to the mass measurements of particles and liquids, individual impingement experiment with hydrophobic or hydrophilic particles of the same otherwise properties is respectively performed under the same conditions. In addition, a series of collection bins are distributed along the spray path to determine the statistical probability of collision properties including coating thickness. Based on these measurements, the collision-induced momentum transfer and velocity redistribution of solids and droplets can be estimated with the aid of a Lagrangian trajectory model. Consequently a general two-parameter of collision probability density function is proposed.
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Chong, Shao Teng, Venkat Raman, Michael E. Mueller, and Hong G. Im. "The Role of Recirculation Zones in Soot Formation in Aircraft Combustors." In ASME Turbo Expo 2018: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/gt2018-76217.

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Recirculation zone plays an important role in flame stabilization in combustors and gas turbines. The location, size, and strength of recirculation zones are important features of a combustor. However, the quantitative role of recirculation zones in affecting soot formation from an aero combustor is not fully understood. In a turbulent flow field with swirling flows and high frequency oscillations of the inflow jets, inner recirculation zones and outer recirculation zones have different functions in determining soot evolution. In this study, large-eddy simulation (LES) of soot formation with detailed physical and chemical models is used in order to study the dynamic aspects of soot formation. The soot population is modeled using the hybrid method of moments (HMOM), while the gas phase precursor evolution is modeled using detailed chemical kinetics. A model aero combustor, studied experimentally at DLR, is used as the baseline flow configuration. The simulations are used to understand the transport of soot particles within such complex flows. In particular, the ability of recirculation regions to increase soot formation by increasing residence times is explored. A Lagrangian particle tracking (LPT) analysis is carried out and statistical roles of recirculation zones are determined from these streamlines. Furthermore, source term analysis of these particles are performed to determine the key physical processes that contribute to soot mass in the recirculation zones. From a numerical stand-point, such soot evolution introduces limitations for statistical convergence, which will also be discussed. In particular, a time-scale analysis will be conducted to determine total computational time needed to obtain converged soot statistics.
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Ambrose, Stephen, Hervé Morvan, and Kathy Simmons. "Investigation of Oil Jet Impingement on a Rotating Gear Using Lattice Boltzman Method (LBM)." In ASME Turbo Expo 2018: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/gt2018-76371.

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In the drive for greater increases in fuel efficiency and reductions in CO2 emissions from aero engines, an epicyclic reduction gearbox can be used to break the link between the turbine and fan, enabling the engine to run at a higher bypass ratio. However, even small power losses can generate significant amounts of heat, due to the high loads transmitted from the gearbox. A substantial amount of cooling is required to remove this heat and a large part of this is supplied directly to the gear face. Assessing the performance of coolants and minimising the buildup of oil in the system is therefore a critical stage in the design process. Traditionally, finite volume CFD methods have been used to compute flow and heat transfer solutions. More recently, Lagrangian methods such as Smoothed Particle Hydrodynamics (SPH) have also been applied. The Lattice Boltzman Method (LBM) is a mesoscopic particle based method which uses statistical properties of particles based at each point of a lattice to calculate flow properties. This is a fully transient method and allows for a simple and efficient derivation of LES turbulence properties. In this work the Lattice Bolztman Method is used to investigate the impingement of an oil jet on a rotating spur gear. A comparison of LBM simulations is made against published work using other methods such as SPH and CFD — utilising the Volume of Fluid method — as well as a qualitative comparison with published experimental high speed images. These all show an excellent agreement and the simulations take the same order of magnitude of computational power as 3D single phase SPH, but are fully multiphase and have LES turbulence. This method is then used to investigate how changes to the oil feed delivery rate affect the spreading of the oil jet on the gear tooth and the splashing profiles. The potential for applying this method to other scenarios, such as lubricating and cooling meshing gears, is also discussed.
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Diounou, E., P. Fede, R. Fournier, S. Blanco, and O. Simonin. "Kinetic Approach for Solid Inertial Particle Deposition in Turbulent Near-Wall Region Flow Lattice Boltzmann Based Numerical Resolution." In ASME-JSME-KSME 2011 Joint Fluids Engineering Conference. ASMEDC, 2011. http://dx.doi.org/10.1115/ajk2011-12021.

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The purpose of the paper is the deposition on the wall of inertial solid particles suspended in turbulent flow. The modeling of such a system is based on a statistical description using a Probability Density Function. In the PDF transport equation, an original model proposed Aguinaga et al. (2009) is used to close the term representing the fluid-particle interactions. The resulting kinetic equation may be difficult to solve especially in the case of the particle response time is smaller than the integral time scale of the turbulence. In the present paper, the Lattice Boltzmann Method is used in order to overcome such numerical problems. The accuracy of the method and its ability to solve the two-phase kinetic equation is analyzed in the simple case of inertial particles in homogeneous isotropic turbulence for which Lagrangian random walk simulation results are available. The results from LBM are in accordance with the random walk simulations.
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