摘要:

This study focuses on the unstructured-mesh multi-grid computation of two-dimensional, steady, transonic Rows governed by the Euler or Navier-Stokes equations (in the laminar, low-Reynolds number regime). The central question is the construction of an algorithm of truly O(N) complexity for second-order accurate schemes. This is achieved either by the ldquo;first-order/second-order” Defect-Correction process, or directly by a fully ldquo;second-order” approach. Relations between levels are controlled by a coarsening method introduced by Guillard. This work attempts to follow the available theoretical facts to build several strategies that are then evaluated for a set of airfoil flows.

ISSN:1061-8562    

DOI:10.1080/10618569508940740

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

The development of a pressure-based Euler scheme, based on a collocated grid arrangement and solving for Cartesian mass flux components is described. An implicit numerical dissipation model, which includes second and fourth difference terms expressed in pressure, is demonstrated. A smoothing function, which includes a two-level filter, is used to adjust the second order-dissipation. The successful calculations for the inviscid transonic aerodynamic flow around airfoil NACA0012 are presented. The transonic quasi-one-dimensional flow calculation in a converging-diverging nozzle is chosen as an example of an internal flow simulation.

ISSN:1061-8562    

DOI:10.1080/10618569508940741

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

A new numerical method is developed for the two-dimensional, steady Navier-Stokes equations. Using local polynomial expansions to represent the discrete primitive variables on each cell, we construct a scheme which has the following properties: First, the local discrete primitive variables are functional solutions of both the integral and differential forms of the Navier-Stokes equations. Second, fluxes are balanced across cell interfaces using exact functional expressions (to the order of accuracy of the local expansions). No interpolation, flux models, or flux limiters are required. Third, local and global conservation of mass, momentum, and energy are explicitly provided for. Finally, the discrete primitive variables and their derivatives are treated in a unified and consistent manner. All are treated as unknowns to be solved together for simulating the local and global flux conservation.

ISSN:1061-8562    

DOI:10.1080/10618569508940742

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

A mixed finite element method was applied to solve a set of elliptic partial differential equations which corresponds to steady-state incompressible laminar flow. To obtain stable solutions at high Reynolds numbers, the Petrov-Galerkin finite element method was used to discretize the advective flux terms with a biquadratic velocity-bilinear pressure element. A priori knowledge of the M-matrix has been used as an underlying guide to enhance the solution stability. The main impetus and effort involve designing a test space of an exponential type. The test cases considered and the results obtained show that the proposed Petrov-Galerkin method is highly reliable and applicable to a wide range of flow conditions.

ISSN:1061-8562    

DOI:10.1080/10618569508940743

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

This paper describes a computational procedure for the optimization of the performance parameters of a simulated annular combustor. This method has been applied to analyze the influence of the performance parameters and geometries on the annular combustor characteristics and provide a good understanding of combustor internal flow fields, and therefore it can be used for guiding the combustor design process. The approach is based on the solution of governing nonlinear, elliptic partial differential equations for 3-D axisymmetric recirculating turbulent reacting swirling flows and the modelling of turbulence, combustion, thermal radiation and pollutant formation. The turbulence effects are introduced via the modified two-equation κ-ϵ model. Turbulent combustion is modelled using the κ-ϵ-g model and a two-step turbulent combustion model is employed for the excess emission of carbon monoxide CO. For the evaluation of the NO pollutant formation rate, the NO pollutant formation model, which takes into account the influence of turbulence, presented here. The radiative heat transfer is handled by the heat flux model. The predictions of the combustor character-istics and performance parameters are made using the present approach.

ISSN:1061-8562    

DOI:10.1080/10618569508940744

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

The numerical simulation of the gaseous flow originated by a gunshot both during the projectile motion within the muzzle and out of it is considered. The numerical solution of the Euler equations is obtained via a second order accurate ENO scheme. A special algorithm of cells reorganization is developed for computing the projectile motion out of the muzzle. It reveals an interesting property of the ENO schemes and Roe's approximate solution of automatically capturing discontinuities by means of the choice of the corresponding grid velocity. The algorithm developed describes sufficiently well all gasdynamics phenomena which accompany the gunshot.

ISSN:1061-8562    

DOI:10.1080/10618569508940745

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

A modified turbulence model, incorporating anisotropic effects into the standard κ-ϵ model, is proposed for the numerical simulation of swirling recirculating flow in a pipe expansion. The new modification follows the concept that the correction to the standard κ-ϵ model is made only in the flow regions where the anisotropic effects are appreciable. The performance of the present hybrid κ-ϵ model for two swirling flows with moderate and high swirl levels is better than that of the standard κ-ϵ model and the modified κ-ϵ model proposed by Abujelala and Lilley and is also competitive with our previously developed hybrid κ-ϵ model. Moreover, the present hybrid modification provides a relatively simpler form compared to our previously developed model; this also helps alleviate the numerical instability in the calculation procedure. Encouraging improvement in the prediction of the size of the central toroidal recirculation zone using the present hybrid modification is also exhibited

ISSN:1061-8562    

DOI:10.1080/10618569508940746

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

ISSN:1061-8562    

DOI:10.1080/10618569508940747

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor