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NONLINEAR VIBRATION CHARACTERISTICS ANALYSIS OF variable density PRINTING MOVING MEMBRANE

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NONLINEAR VIBRATION CHARACTERISTICS ANALYSIS OF VARIABLE DEN...

Stability of stratified shear flows in channels with variable cross sections

2016年全国压电和声波理论及器件应用研讨会

作者： Ji-mei WU Zhen TIAN Yan WANG Xu-xia GUO Institute of Printing and Packing Engineering Xi'an University of Technology School of civil engineering and architecture Xi'an University of Technology Mechanical and Electrical Engineering Department Baoji University of Arts and Sciences

ISBN: (纸本)9781509011902

Background, Motivation and Objective Membrane as a printing material widely used in the field of printing and packaging. The transverse vibration of high-speed membrane in the printing process and the "fold" phenomenon caused by vibration will seriously affect the printing overprint precision, thus affect its quality. On many occasions the membrane density is non constant, such as printing paper and PET film etc.. Uneven surface density will affect the vibration characteristics of the membrane, reduce the stability of the printing, and thus affect the quality of printing. So the study of nonlinear vibration characteristics of variable density moving membrane have great significance to effectively control the vibration of the membrane in printing process, improve the printing overprint precision. Statement of Contribution/Methods The model of the moving membrane with parabolic density was established. Then, the Von Karman equations expressed by the deflection function and the internal force function of axially moving membrane are derived based on the theory of elasticity. The nonlinear vibration characteristics of the variable density moving membrane under clamped boundary are studied. The time and spatial variables are separated by Bubnov-Galerkin method and the nonlinear vibration frequency expression of the variable density moving membrane is obtained. Results The relation curve of frequency and density coefficient, velocity, length and width ratio are obtained. The effects of velocity, length width ratio, density coefficient and initial value of vibration on the nonlinear vibration of printing membranes are discussed. Discussion and Conclusions In the same density coefficient and initial motion, the larger the length and width ratio, the greater the critical speed of the membrane. That is to say increasing the length and width ratio of the membrane can improve the critical speed of the membrane. Under the same aspect ratio and the initial motion condition, the la

关键词： Nonlinear vibration Dynamic stability variable density Moving membrane

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Applied Mathematics and Mechanics(English Edition) 2015年第11期36卷 1459-1480页

作者： V.R.REDDY M.SUBBIAH Department of Mathematics Pondicherry University

For the instability problem of density stratified shear flows in sea straits with variable cross sections, a new semielliptical instability region is found. Rurthermore, the instability of the bounded shear layer is studied in two cases：（i） the density which takes two different constant values in two layers and （ii） the density which takes three different constant values in three layers. In both cases, the dispersion relation is found to be a quartic equation in the complex phase velocity. It is found that there are two unstable modes in a range of the wave numbers in the first case, whereas there is only one unstable mode in the second case.

关键词： hydrodynamic stability shear flow variable density sea strait variablecross section

Efficient variable-Coefficient Finite-Volume Stokes Solvers

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Communications in Computational Physics 2014年第10期16卷 1263-1297页

作者： Mingchao Cai Andy Nonaka John B.Bell Boyce E.Griffith Aleksandar Donev Courant Institute of Mathematical Sciences New York UniversityNew YorkNY 10012USA. Center for Computational Sciences and Engineering Lawrence Berkeley National LaboratoryBerkeleyCA 94720USA. Leon H.Charney Division of Cardiology Department of MedicineNew York University School of MedicineNYUSA. Department of Mathematics University of North CarolinaChapel HillNC 27599USA

We investigate several robust preconditioners for solving the saddle-point linear systems that arise from spatial discretization of unsteady and steady variablecoefficient Stokes equations on a uniform staggered *** on the success of using the classical projection method as a preconditioner for the coupled velocitypressure system[***,***.,228(2009),pp.7565–7595],as well as established techniques for steady and unsteady Stokes flow in the finite-element literature,we construct preconditioners that employ independent generalized Helmholtz and Poisson solvers for the velocity and pressure *** demonstrate that only a single cycle of a standard geometric multigrid algorithm serves as an effective inexact solver for each of these *** to traditional wisdom,we find that the Stokes problem can be solved nearly as efficiently as the independent pressure and velocity subproblems,making the overall cost of solving the Stokes system comparable to the cost of classical projection or fractional step methods for incompressible flow,even for steady flow and in the presence of large density and viscosity *** of the five preconditioners considered here are found to be robust to GMRES restarts and to increasing problem size,making them suitable for large-scale *** work opens many possibilities for constructing novel unsplit temporal integrators for finite-volume spatial discretizations of the equations of low Mach and incompressible flow dynamics.

关键词： Stokes flow variable density variable viscosity saddle point problems projection method preconditioning GMRES.

SPLITTING SCHEMES FOR A NAVIER-STOKES-CAHN-HILLIARD MODEL FOR TWO FLUIDS WITH DIFFERENT DENSITIES

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Journal of Computational Mathematics 2014年第6期32卷 643-664页

作者： Francisco Guillen-Gonzalez Giordano Tierra Departamento de Ecuaciones Diferenciales y Andlisis Numgrico and IMUS Universidad de Sevilla 41012 Seville Spain Department of Applied and Computational Mathematics and Statistics University of Notre Dame Notre Dame IN 46556 USA

In this work, we focus on designing efficient numerical schemes to approximate a ther- modynamically consistent Navier-Stokes/Cahn-Hilliard problem given in [3] modeling the mixture of two incompressible fluids with different densities. The model is based on a diffuse-interface phase-field approach that is able to describe topological transitions like droplet coalescense or droplet break-up in a natural way. We present a splitting scheme, decoupling computations of the Navier-Stokes part from the Cahn-Hilliard one, which is unconditionally energy-stable up to the choice of the potential approximation. Some nu- merical experiments are carried out to validate the correctness and the accuracy of the scheme, and to study the sensitivity of the scheme with respect to different physical pa- rameters.

关键词： Two-phase flow Diffuse-interface phase-field Cahn-Hilliard Navier-Stokes,Energy stability variable density Mixed finite element Splitting scheme.

Comparison of Three Brine Migration Models in Groudwater

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Journal of Groundwater Science and Engineering 2013年第1期1卷 70-73页

作者： Yu Liu Hydrogeology Department Faculty of GeologyMoscow State University

Three brine migration models in underground waters were compared to solve the problem of high-density brine migration in underground fresh waters. As shown by the example of brine occurrence in salt dumps, it is prefe... 详细信息

关键词： brine migration variable density