Numerical Dissipation (numerical + dissipation)

Distribution by Scientific Domains

Selected Abstracts

Some finite difference methods for a kind of GKdV equations

X. Lai
Abstract In this paper, some finite difference schemes I, II, III and IV, are investigated and compared in solving a kind of mixed problem of generalized Korteweg-de Vries (GKdV) equations especially the relative errors. Both the numerical dispersion and the numerical dissipation are analysed for the constructed difference scheme I. The stability is also obtained for scheme I and the constructed predictor,corrector scheme IV by using a linearized stability method. Other two schemes, II and III, are also included in the comparison among these four schemes for the numerical analysis of different GKdV equations. The results enable one to consider the relative error when dealing with these kinds of GKdV equations. Copyright 2006 John Wiley & Sons, Ltd. [source]

A variationally consistent framework for the design of integrator and updates of generalized single step representations for structural dynamics

R. Kanapady
Abstract A variationally consistent framework leading to the concise design of both the ,integrator' and the associated ,updates' as related to the single step representations encompassing the so-called LMS methods for structural dynamics is described. The present paper shows for the first time, a consistent treatment involving both the ,integrator' and ,updates' that are inherent in the general context of designing the time integration process. Furthermore, the framework encompasses not only all the existing time integration algorithms that are dissipative and non-dissipative within the scope of LMS methods but also contains new optimal algorithms useful for practical applications,in the sense of accuracy, stability, numerical dissipation and dispersion, and overshoot characteristics of computational algorithms for time dependent problems encountered in structural dynamics. Copyright 2003 John Wiley & Sons, Ltd. [source]

A two-step Taylor-characteristic-based Galerkin method for incompressible flows and its application to flow over triangular cylinder with different incidence angles

Yan Bao
Abstract An alternative characteristic-based scheme, the two-step Taylor-characteristic-based Galerkin method is developed based on the introduction of multi-step temporal Taylor series expansion up to second order along the characteristic of the momentum equation. Contrary to the classical characteristic-based split (CBS) method, the current characteristic-based method does not require splitting the momentum equation, and segregate the calculation of the pressure from that of the velocity by using the momentum,pressure Poisson equation method. Some benchmark problems are used to examine the effectiveness of the proposed algorithm and to compare with the original CBS method, and the results show that the proposed method has preferable accuracy with less numerical dissipation. We further applied the method to the numerical simulation of flow around equilateral triangular cylinder with different incidence angles in free stream. In this numerical investigation, the flow simulations are carried out in the low Reynolds number range. Instantaneous streamlines around the cylinder are used as a means to visualize the wake region behind, and they clearly show the flow pattern around the cylinder in time. The influence of incidence angle on flow characteristic parameters such as Strouhal number, Drag and Lift coefficients are discussed quantitatively. Copyright 2009 John Wiley & Sons, Ltd. [source]

Volume-of-fluid-based model for multiphase flow in high-pressure trickle-bed reactor: Optimization of numerical parameters

AICHE JOURNAL, Issue 11 2009
Rodrigo J. G. Lopes
Abstract Aiming to understand the effect of various parameters such as liquid velocity, surface tension, and wetting phenomena, a Volume-of-Fluid (VOF) model was developed to simulate the multiphase flow in high-pressure trickle-bed reactor (TBR). As the accuracy of the simulation is largely dependent on mesh density, different mesh sizes were compared for the hydrodynamic validation of the multiphase flow model. Several model solution parameters comprising different time steps, convergence criteria and discretization schemes were examined to establish model parametric independency results. High-order differencing schemes were found to agree better with the experimental data from the literature given that its formulation includes inherently the minimization of artificial numerical dissipation. The optimum values for the numerical solution parameters were then used to evaluate the hydrodynamic predictions at high-pressure demonstrating the significant influence of the gas flow rate mainly on liquid holdup rather than on two-phase pressure drop and exhibiting hysteresis in both hydrodynamic parameters. Afterwards, the VOF model was applied to evaluate successive radial planes of liquid volume fraction at different packed bed cross-sections. 2009 American Institute of Chemical Engineers AIChE J, 2009 [source]