Search results

1 – 10 of 11
To view the access options for this content please click here
Article
Publication date: 1 December 2000

I.V. Sergienko, V.M. Yanenko, O.V. Gaiduk, N.I. Proskura and N.V. Yanenko

The computer technology (CT) for modelling of the ecology‐economic situation in the alienation zone (AZ) of Chenobyl is developed. It includes the databases of potentially…

Abstract

The computer technology (CT) for modelling of the ecology‐economic situation in the alienation zone (AZ) of Chenobyl is developed. It includes the databases of potentially dangerous objects and program modules (PM) for modelling of the ecology‐economic situation in the AZ. The optimal redistribution of means, directed at resource restoration, liquidation of technogenic pollution, the restoration of basis capital, prevention of pollution migration for bounds of the AZ is determined by use of this model. A distinctive feature of the accounts carried out in this work is that they allow the estimation not only of risk value, but also of levels of reserve possiblities of various objects of the AZ. The critical values of measured parameters, at which achievement the emergencies can occur, are also determined. The CT includes the following program modules: geo‐information system; PM for risk assessment of emergency occurences in the AZ; PM for dynamic optimisation tasks.

Details

Environmental Management and Health, vol. 11 no. 5
Type: Research Article
ISSN: 0956-6163

Keywords

To view the access options for this content please click here
Article
Publication date: 1 September 1998

Asuquo B. Ebiana

A computational procedure based on a hybrid Lagrangian‐Eulerian discrete‐vortical element formulation and conformal transformation schemes are employed in this study to…

Abstract

A computational procedure based on a hybrid Lagrangian‐Eulerian discrete‐vortical element formulation and conformal transformation schemes are employed in this study to simulate the interaction of an air jet with swirling air flow inside a two‐dimensional cylinder. Such an investigation is of importance to many flow‐related industrial and environmental problems, such as mixing, cooling, combustion and dispersion of air‐borne or water‐borne contaminants because of the role of vortices in the global transport of matter and heat. The basis for the simulation is discussed and numerical results compared with theoretical results for the velocity field and streamfunction obtained by the method of images. The swirling air motion and the features of a real jet are well simulated and numerical results are validated by predictions of theory to within 20 per cent. To illustrate the merging and interaction processes of vortices and the formation of large eddies, velocity vectors, particle trajectories and streamline contours are presented.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 8 no. 6
Type: Research Article
ISSN: 0961-5539

Keywords

To view the access options for this content please click here
Article
Publication date: 18 September 2009

Yuri N. Skiba and Denis M. Filatov

The purpose of this paper is to suggest a new approach to the numerical simulation of shallow‐water flows both in plane domains and on the sphere.

Abstract

Purpose

The purpose of this paper is to suggest a new approach to the numerical simulation of shallow‐water flows both in plane domains and on the sphere.

Design/methodology/approach

The approach involves the technique of splitting of the model operator by geometric coordinates and by physical processes. Specially chosen temporal and spatial approximations result in one‐dimensional finite difference schemes that conserve the mass and the total energy. Therefore, the mass and the total energy of the whole two‐dimensional split scheme are kept constant too.

Findings

Explicit expressions for the schemes of arbitrary approximation orders in space are given. The schemes are shown to be mass‐ and energy‐conserving, and hence absolutely stable because the square root of the total energy is the norm of the solution. The schemes of the first four approximation orders are then tested by simulating nonlinear solitary waves generated by a model topography. In the analysis, the primary attention is given to the study of the time‐space structure of the numerical solutions.

Originality/value

The approach can be used for the numerical simulation of shallow‐water flows in domains of both Cartesian and spherical geometries, providing the solution adequate from the physical and mathematical standpoints in the sense of keeping its mass and total energy constant even when fully discrete shallow‐water models are applied.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 19 no. 8
Type: Research Article
ISSN: 0961-5539

Keywords

To view the access options for this content please click here
Article
Publication date: 1 April 1992

G.V. Gadiyak, J.L. Korobitsina and V.I. Kranarenko

Computer code complex for the thermal oxidation of silicon is presented. There are one‐dimensional model and two‐ dimensional models:the model of viscoelastic oxide and…

Abstract

Computer code complex for the thermal oxidation of silicon is presented. There are one‐dimensional model and two‐ dimensional models:the model of viscoelastic oxide and the hydrodynamical models — an ideal fluid and a viscous fluid models. If nitride mask is absent, a one‐dimensional model is used.The influence of an induced stress on the diffusion and reaction is taken into account.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 11 no. 4
Type: Research Article
ISSN: 0332-1649

To view the access options for this content please click here
Article
Publication date: 6 November 2017

J.I. Ramos

The purpose of this paper is to develop a new finite-volume method of lines for one-dimensional reaction-diffusion equations that provides piece-wise analytical solutions…

Abstract

Purpose

The purpose of this paper is to develop a new finite-volume method of lines for one-dimensional reaction-diffusion equations that provides piece-wise analytical solutions in space and is conservative, compare it with other finite-difference discretizations and assess the effects of the nonlinear diffusion coefficient on wave propagation.

Design/methodology/approach

A conservative, finite-volume method of lines based on piecewise integration of the diffusion operator that provides a globally continuous approximate solution and is second-order accurate is presented. Numerical experiments that assess the accuracy of the method and the time required to achieve steady state, and the effects of the nonlinear diffusion coefficients on wave propagation and boundary values are reported.

Findings

The finite-volume method of lines presented here involves the nodal values and their first-order time derivatives at three adjacent grid points, is linearly stable for a first-order accurate Euler’s backward discretization of the time derivative and has a smaller amplification factor than a second-order accurate three-point centered discretization of the second-order spatial derivative. For a system of two nonlinearly-coupled, one-dimensional reaction-diffusion equations, the amplitude, speed and separation of wave fronts are found to be strong functions of the dependence of the nonlinear diffusion coefficients on the concentration and temperature.

Originality/value

A new finite-volume method of lines for one-dimensional reaction-diffusion equations based on piecewise analytical integration of the diffusion operator and the continuity of the dependent variables and their fluxes at the cell boundaries is presented. The method may be used to study heat and mass transfer in layered media.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 27 no. 11
Type: Research Article
ISSN: 0961-5539

Keywords

To view the access options for this content please click here
Article
Publication date: 1 May 1994

P. Glaister

A shock capturing scheme is presented for the equations of isentropicflow based on upwind differencing applied to a locally linearized set ofRiemann problems. This…

Abstract

A shock capturing scheme is presented for the equations of isentropic flow based on upwind differencing applied to a locally linearized set of Riemann problems. This includes the two‐dimensional shallow water equations using the familiar gas dynamics analogy. An average of the flow variables across the interface between cells is required, and this average is chosen to be the arithmetic mean for computational efficiency, leading to arithmetic averaging. This is in contrast to usual ‘square root’ averages found in this type of Riemann solver where the computational expense can be prohibitive. The scheme is applied to a two‐dimensional dam‐break problem and the approximate solution compares well with those given by other authors.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 4 no. 5
Type: Research Article
ISSN: 0961-5539

Keywords

To view the access options for this content please click here
Article
Publication date: 1 October 1995

C. Demetriou, R.E. Volker and A.J. Johnston

A computer model based on the fractional step method is presented formodelling density coupled mass transport in groundwater. Although severalmodels utilising the…

Abstract

A computer model based on the fractional step method is presented for modelling density coupled mass transport in groundwater. Although several models utilising the fractional step method had been developed previously, all were based on the Eulerian solution approach. The model developed by the authors uses the Langrangian approach which has some inherent advantages and disadvantages. The problems associated with the implementation of the fractional step method and techniques by which they were overcome are discussed. The performance of the model is examined and results obtained for standard problems are compared with those from other computer packages.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 5 no. 10
Type: Research Article
ISSN: 0961-5539

Keywords

To view the access options for this content please click here
Article
Publication date: 1 March 2002

Brian J. McCartin and Sydney B. Forrester

This paper describes a numerical approximation scheme for the one‐dimensional Streeter‐Phelps equations of river self‐purification. Our formulation of the problem includes…

Abstract

This paper describes a numerical approximation scheme for the one‐dimensional Streeter‐Phelps equations of river self‐purification. Our formulation of the problem includes second order kinetics in a coordinate system moving with the river thus analytically accounting for convection. These equations are linearized by using fractional time steps. The effects of reaeration and deoxygenation are accommodated by exponential fitting. The discrete equations are then marched forward in time using the hopscotch scheme which is explicit yet unconditionally stable (albeit conditionally consistent). Numerical examples both with and without dispersion are presented which indicate that the proposed method is much more efficient than a brute force numerical approach. Specifically, the proposed explicit scheme is amenable to parallel implementation.

Details

Engineering Computations, vol. 19 no. 2
Type: Research Article
ISSN: 0264-4401

Keywords

To view the access options for this content please click here
Article
Publication date: 1 April 1988

Yu.A. BEREZIN and O.E. DMITRIEVA

In this paper, the authors describe a more efficient and economical method for a splitting scheme for drift‐diffusion models for semiconductors. It enables one to…

Abstract

In this paper, the authors describe a more efficient and economical method for a splitting scheme for drift‐diffusion models for semiconductors. It enables one to calculate stationary and non‐stationary processes in semiconductor plasma.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 7 no. 4
Type: Research Article
ISSN: 0332-1649

To view the access options for this content please click here
Article
Publication date: 1 February 1996

C.W. Li and F. Zhang

A three‐dimensional numerical model is developed to study the motion andmixing process induced by thermals. The model utilizes a split‐operatorapproach for the solution of…

Abstract

A three‐dimensional numerical model is developed to study the motion and mixing process induced by thermals. The model utilizes a split‐operator approach for the solution of the hydrodynamic equations and the advective diffusion equation. A conservative characteristics based scheme with flux‐limiter is employed to accurately approximate the advective terms in all equations and to prevent the generation of over and under shoots in the solution. In modelling the turbulent stresses and diffusion, the mixing length model is used. Cases of unit thermals in uniform or stratified ambient fluid and advected line thermals are simulated and the results verify the empirical equations for thermal parameters obtained from the reported experimental data.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 6 no. 2
Type: Research Article
ISSN: 0961-5539

Keywords

1 – 10 of 11