摘要:

A space-time finite element method based on the Arbitrary Lagrangian-Eulerian description of the incompressible Navier-Stokes Equations is developed. The developed method is used for predicting the flows past bodies in relative motion. The governing equations are expressed in a fixed frame of reference, wherein the terms related to grid motion are included. Superparametric space-time elements are used in the discretization of the domain in which, finite elements are both allowed to move and deform in (i) simple and (ii) automatic manner. The equations for the rigid body motion are integrated to calculate the trajectory of the moving object under aerodynamic and gravitational forces. The code developed here is first tested on the flow about a drifting and falling sphere which starts to move at Reynolds number of 104from a steady state. To study the flows about the bodies in relative motion, store-separation from a wing problem is investigated as a turbulent flow for the Reynolds number of 2.5 x 106based on the length of the store.

ISSN:1061-8562    

DOI:10.1080/10618560008940712

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

Introduced in the late eighties by Roe, fluctuation splitting (or residual distribution) schemes have recently emerged as a viable alternative to Finite Volume and Finite Element methods for PDE based, fluid dynamics simulations using unstructured meshes. Their application to the numerical approximation of the compressible and incompressible Euler and Navier-Stokes equations is described, emphasizing low Mach number and incompressible applications. The advantages provided by time-preconditioning techniques are discussed and details of the implementation are given.

ISSN:1061-8562    

DOI:10.1080/10618560008940713

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

The present work represents the first attempt at studying the unsteadiness of jet-in-crossflows using the Reynolds-Averaged Navier-Stokes (RANS) equations. In the past, numerical studies of jet-in-crossflows, with the exception of the few attempts of DNS and LES. are always carried out under the assumption that the flowfield is steady and symmetric about the jet center plane. Growing experimental evidence suggests that this flow is unsteady and periodic. The present work verified the existence of periodicity in jet-in-crossflows numerically. The numerically predicted Slrouhal number is in good agreement with experimental observations. In addition, the present simulation of the jet-in-crossflow were able to resolve the details of flow structures such as the oscillating wake structures, the jet shear-layer vortices, and the counter-rotating vortex pairs.

ISSN:1061-8562    

DOI:10.1080/10618560008940714

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

The results of comparative analysis of some nonlinear dispersive models of shallow water are presented. The aim is to find their individual properties relevant for the numerical solution of some model problems of long wave transformation over submerged obstacles The study considers basic properties of the listed models and their numerical implementation. Computations are obtained compared with the analytical solution and experimental data. Attention is primarily focused on the models suggested by Peregrine (1967); Zheleznyak and Pelinovsky (1985); Kim, Reid, Whitakcr (1988): Fedotova and Pashkova (1997). Also classical equations of shallow water are considered in both linear and nonlinear approximations.

ISSN:1061-8562    

DOI:10.1080/10618560008940715

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

Two-dimensional incompressible Navier-Stokes equations are solved numerically to model the thermohydrodynamic performance of a dynamically loaded journal bearing which is modeled as eccentrically rotating cylinders. The region between those cylinders are occupied by Newtonian lubricants, whose physical properties such as viscosity and thermal conductivity are assumed to be functions of local temperature. A single domain pseudospectral method which combines Fourier expansions and Chebyshev polynomials for spatial discretization is introduced in conjunction with appropriate time marching scheme for the unsteady incompressible Navier-Stokes equations. The selection of these polynomial functions is favorable since both FFT algorithms for Fourier and Chebyshev expansions are easily available. In this numerical model, the journal is dynamically loaded by an external force and set free, so that its center moves in such a way to strike a balance between the applied load and the hydrodynamic forces. The pseudo-spectral scheme is then applied to a few classical problems, such as concentric rotating cylinders and journal bearings with lubricants of constant and varying (temperature dependent) viscosity to establish the validity of the numerical scheme in simulating these problems realistically as well as to gauge the convergence characteristics and relevant numerical issues. The numerical modeling has been found to be reasonably accurate and robust enough to serve as a tool for the study the flow in the region between the journal and the bearing.

ISSN:1061-8562    

DOI:10.1080/10618560008940716

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

The two-dimensional flow of viscous incompressible liquid in a square cavity with a Tree boundary and differentially heated vertical sides is considered in the present work. The influence of gravitational and thermocapillary convection on temperature and velocity fields is studied in a large range of dimensionless parameters and similarity criteria using method of exponential fitting discretization. Limiting cases of dimensionless parameters are analyzed numerically.

ISSN:1061-8562    

DOI:10.1080/10618560008940717

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor