The Experts below are selected from a list of 20523 Experts worldwide ranked by ideXlab platform
J M Mcdonough - One of the best experts on this subject based on the ideXlab platform.
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low order Discrete Dynamical System for h2 air finite rate chemistry in 3d
2014Co-Authors: Wenwei Zeng, J M McdonoughAbstract:A low-order Discrete Dynamical System (DDS) model for finite-rate chemistry of H2-air combustion is derived in 3D. Simulation is performed in the context of a new subgrid-scale (SGS) method. Regime maps are used to determine useful ranges of values for bifurcation parameters. Specifically, a nine-step mechanism of H2-air reactions with N2-dilution is studied. As input to the DDS model, one fixed position within the flow chosen from Meier et al., is used (Combustion Science and Technology, 1996). The results in terms of time series of velocities, species mass fractions and the sum of mass fractions are analyzed. Moreover, the results are compared with experimental data at the selected position in the flame field. Discrepancies between computed and experimental results are discussed, and possible causes for discrepancies are analyzed. The potential of applying the current DDS in large-eddy simulation is addressed.
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three dimensional poor man s navier stokes equation a Discrete Dynamical System exhibiting k 5 3 inertial subrange energy scaling
Physical Review E, 2009Co-Authors: J M McdonoughAbstract:Outline of the derivation and mathematical and physical interpretations are presented for a Discrete Dynamical System known as the "poor man's Navier-Stokes equation." Numerical studies demonstrate that velocity fields produced by this Dynamical System are similar to those seen in laboratory experiments and in detailed simulations, and they lead to scaling for the turbulence kinetic energy spectrum in accord with Kolmogorov K41 theory.
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response to strain rate in a Discrete Dynamical System model of the high wavenumber navier stokes equations
Journal of Turbulence, 2003Co-Authors: J M Mcdonough, S A Bible, J ScovilleAbstract:The ‘poor man's Navier–Stokes’ subgrid-scale model for use in large-eddy simulation is discussed with focus on its relationship to physics via its derivation from the Navier–Stokes equations. This Discrete Dynamical System is computationally inexpensive permitting thorough numerical study before its implementation as a subgrid-scale model. Previously we have demonstrated ranges of independent parameter values suitable for use in large-eddy simulations while maintaining a strict coupling of the equations through equating selected strain-rate tensor components. Here we will remove this restriction and again investigate the suitable ranges of bifurcation parameters through their two-dimensional bifurcation diagrams. Additionally we will comment on the possible impacts of our findings with regard to implementation of the subgrid-scale model in large-eddy simulations.
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Discrete Dynamical System models of turbulence-chemical kinetics interactions
IECEC '02. 2002 37th Intersociety Energy Conversion Engineering Conference 2002., 2002Co-Authors: J M McdonoughAbstract:An approach to subgrid-scale (SGS) modeling for large-eddy simulation of turbulent non-premixed combustion is proposed and tested against experimental data. The model is composed of three specific factors: an amplitude, an anisotropy correction and a temporal fluctuation to be evaluated at each Discrete point, during each time step, of resolved-scale calculations. We employ Discrete Dynamical Systems (DDSs) for the third factor and in the present work focus on construction of these for a reduced kinetic mechanism and compare results with experimental data from the Technische Universitat Darmstadt H/sub 2//N/sub 2/-air jet diffusion flame H/sub 3/. The DDS model is derived as a single-mode Galerkin approximation (with the mode left arbitrary) of the governing partial differential equations, but with the mode number and normalization (s) incorporated into bifurcation parameters. Such algebraic Systems are capable of producing the full range of temporal behaviors of the original differential equations (while being very efficient to evaluate) and, in particular, can exhibit the chaotic behavior of fractal (strange) attractors that can be associated with turbulence. Moreover, they are able to mimic specific reaction pathways for any given kinetic mechanism on the subgrid scales. We compare computed results from the SGS model with the above mentioned data, both qualitatively (appearance of the time series) and quantitatively (rms fluctuation levels) and show reasonable agreement, especially for the former.
Jiří Kupka - One of the best experts on this subject based on the ideXlab platform.
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Topological entropy of fuzzified Dynamical Systems
Fuzzy Sets and Systems, 2011Co-Authors: Jose S. Cánovas, Jiří KupkaAbstract:A Discrete Dynamical System is given by a compact metric space X and any continuous self-map defined on X. This Discrete Dynamical System can be naturally extended to the space of fuzzy sets on X. In this paper we study relations between the sizes of the topological entropies of the original Dynamical System and of its fuzzy counterpart. Among other things, we present a constructive proof of the fact that even very weak assumptions on the crisp Discrete Dynamical System ensure infinite topological entropy of the fuzzy System. However, we also show that there are subSystems of the fuzzy Dynamical System with topological entropy equal to that of the crisp Dynamical System.
Song Xiao-qian - One of the best experts on this subject based on the ideXlab platform.
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Composite Variable-parametric Discrete Dynamical System
Journal of Chongqing Institute of Technology, 2009Co-Authors: Song Xiao-qianAbstract:This paper investigates the basic Dynamical properties among the composite of variable-parametric Discrete Dynamical System(X,FG),the ordinary Variable-parametric Discrete Dynamical System(X,F) and(X,G).It is proved that if F is transitivity, mixing,and strong transitivity,and G satisfies certain condition,so is FG.As a result,it is concluded that the Dynamical properties of FG can be inherit from the properties of F and G.
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On generator of variable-parametric Discrete Dynamical System
Journal of Science of Teachers' College and University, 2009Co-Authors: Song Xiao-qianAbstract:Given the definition of generator and weak generator for variable-parametric Discrete Dynamical System.The fact that the variable-parametric Discrete Dynamical System has generator if and only if it has weak generator was proved,and studied other properties of generator.These results further extend the scope of the research on variable-parametric Discrete Dynamical System.
Leszek Szała - One of the best experts on this subject based on the ideXlab platform.
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Chaotic behaviour of uniformly convergent non-autonomous Systems with randomly perturbed trajectories
Journal of Difference Equations and Applications, 2015Co-Authors: Leszek SzałaAbstract:We study non-autonomous Discrete Dynamical Systems with randomly perturbed trajectories. We suppose that such a System is generated by a sequence of continuous self-maps of [0,1]m, where m is a positive integer, and the sequence converges uniformly to a map f. We give conditions, under which a recurrent point of a (standard) autonomous Discrete Dynamical System generated by the limit function f is also recurrent for the non-autonomous System with randomly perturbed trajectories. We also provide a sufficient condition for a non-autonomous Discrete Dynamical System defined on the unit interval to be non-chaotic in the sense of Li and Yorke with respect to small random perturbations.
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Chaotic behavior of uniformly convergent nonautonomous Systems with randomly perturbed trajectories
arXiv: Dynamical Systems, 2014Co-Authors: Leszek SzałaAbstract:We study nonautonomous Discrete Dynamical Systems with randomly perturbed trajectories. We suppose that such a System is generated by a sequence of continuous maps which converges uniformly to a map $f$. We give conditions, under which a recurrent point of a (standard) autonomous Discrete Dynamical System generated by the limit function $f$ is also recurrent for the nonautonomous System with randomly perturbed trajectories. We also provide a necessary condition for a nonautonomous Discrete Dynamical System to be nonchaotic in the sense of Li and Yorke with respect to small random perturbations.
Himadri Kumar Mukerjee - One of the best experts on this subject based on the ideXlab platform.
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Strong Conley index over a phase space
Topology and its Applications, 2016Co-Authors: Sainkupar Marwein Mawiong, Himadri Kumar MukerjeeAbstract:Abstract We extend the definition of the strong Conley index of a Discrete Dynamical System introduced in [1] to the strong Conley index over a phase space of a Discrete Dynamical System which strengthens the Conley index over a phase space defined in [2] and also generalizes the strong Conley index of a Discrete Dynamical System. We also prove the continuation property of the strong Conley index over a phase space.
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strong shift equivalence and strong conley index
Dynamical Systems-an International Journal, 2016Co-Authors: Sainkupar Marwein Mawiong, Himadri Kumar MukerjeeAbstract:ABSTRACTUsing the strong shift equivalence of pointed space maps associated to filtration pairs for isolated invariant sets of a Discrete Dynamical System we define a strong Conley index independent of the choice of filtration pairs and prove that it is invariant under continuation.