نتایج جستجو برای: moment equations method

تعداد نتایج: 1848949  

Journal: :Computers & Chemical Engineering 2013
Zheng Liu Jonas Roininen Iiro Pulkkinen Tuomo Sainio Ville Alopaeus

Aalto University, P.O. Box 11000, FI-00076 Aalto www.aalto.fi Author Zheng Liu Name of the doctoral dissertation MODELING OF MASS TRANSFER AND REACTIONS WITH THE MOMENT METHOD Publisher School of Chemical Technology Unit Department of Biotechnology and Chemical Technology Series Aalto University publication series DOCTORAL DISSERTATIONS 5/2015 Field of research Chemical Engineering Manuscript s...

Journal: :J. Comput. Physics 2007
X. J. Gu D. R. Emerson

The challenge of modeling low-speed rarefied gas flow in the transition regime is well known. In this paper, we propose a numerical solution procedure for the regularized 13 moment equations within a finite-volume framework. The stress and heat flux equations arising in the method of moments are transformed into the governing equations for the stress and heat flux deviators based on their first...

2016
Khem Raj Ghusinga Cesar A. Vargas-Garcia Andrew Lamperski Abhyudai Singh

In the stochastic formulation of chemical kinetics, the stationary moments of the population count of species can be described via a set of linear equations. However, except for some specific cases such as systems with linear reaction propensities, the moment equations are underdetermined as a lower order moment might depend upon a higher order moment. Here, we propose a method to find lower, a...

Journal: :فیزیک کوانتومی 0

in this paper, lagrangian and equations describing one-dimensional anisotropic non-heisenberg model are studied. in this study we used the generalized coherent states in real parametrizations and the feynman path integral for these states in su(3) group. these equations describe nonlinear dynamics of non-heisenberg ferromagnetic chain completely. solutions of these equations are magnetic solito...

Journal: :SIAM J. Scientific Computing 2013
Zhenning Cai Ruo Li Yanli Wang

In this paper, we propose a moment method to numerically solve the Vlasov equations using the framework of the NRxxmethod developed in [6, 8, 7] for the Boltzmann equation. Due to the same convection term of the Boltzmann equation and the Vlasov equation, it is very convenient to use the moment expansion in the NRxx method to approximate the distribution function in the Vlasov equations. The mo...

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه تبریز 0

a semi-empirical mathematical model for predicting physical part of ignition delay period in the combustion of direct - injection diesel engines with swirl is developed . this model based on a single droplet evaporation model . the governing equations , namely , equations of droplet motion , heat and mass transfer were solved simultaneously using a rung-kutta step by step unmerical method . the...

2010
R. Cubarsi

The closure problem for the stellar hydrodynamic equations is studied by describing the family of phase space density functions, for which the collisionless Boltzmann equation is strictly equivalent to a finite subset of moment equations. It is proven that the redundancy of the higher-order moment equations and the recurrence of the velocity moments are of similar nature. The method is based on...

1998
C. P. Dullemond

The one-dimensional stationary PSTF moment equations for radiative transfer in relativistically differentially moving media are examined. It is found that the equations can have two different types of critical points. In regions of strong velocity gradients, solutions might have pathological behavior around such critical points. The moment method may therefore yield unphysical solutions for the...

2009
Ansgar Jüngel Stefan Krause Paola Pietra Jens Markus Melenk Stefan Sauter Matthias Langer Harald Woracek Winfried Auzinger Felix Kramer Markus Aurada Samuel Ferraz-Leite Dirk Praetorius Laurent Desvillettes Céline Prévost Bertram Düring Daniel Matthes Josipa Pina

Diffusive moment equations with an arbitrary number of moments are formally derived from the semiconductor Boltzmann equation employing a moment method and a Chapman-Enskog expansion. The moment equations are closed by employing a generalized Fermi-Dirac distribution function obtained from entropy maximization. The current densities allow for a drift-diffusion-type formulation or a “symmetrized...

2014
Kim Molvig

A derivation and approximate solution of renormalized mode coupling equations describing the turbulent drift wave spectrum is presented. Arguments are given which indicate that a weak turbulence formulation of the spectrum equations fails for a system with negative dissipation. The inadequacy of the weak turbulence theory is circumvented by utilizing a renormalized formulation. An analytic mome...

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