AN OBJECT-ORIENTED APPROACH IN PROBLEMS OF NUMERICAL HEAT AND MASS TRANSFER

摘要

Application of an Object-Oriented Approach (OOA) toproblems of numerical heat and mass transfer for convectiondiffusionequations has been discussed for several sampleproblems of heat transfer and fluid flow. This method has beendeveloped for numerical schemes based on the control volumemethod and especially for a new finite-difference scheme,called Efficient Finite Differencing (EFD). These problems arerelated to thermal hydraulics analysis of the nuclear power plantcomponents including prediction of the velocity andtemperature distributions in rod bundles.A number of new control volume based methods have beendeveloped recently. They enable a more accurate solution usinga grid with fewer nodes. However, their application is morecomplicated in programming. Although central difference andexponential schemes can be easily realised by traditionalmethods and ways of programming, for example, usingFORTRAN language, new schemes require application of muchmore complex algorithms and new way of their implementation.We think that one of convenient ways for analysing this kind ofproblems is the object-oriented approach which gives greatpossibilities of describing transport phenomena taking intoconsideration their inherent physical properties. Since differentcontrol volume–based methods have common basis, this basecould be described. Making some modifications and additionsone can derive a specific scheme and compare effectiveness ofdifferent schemes. OOA allows to obtain modifications of ascheme easily and in a convenient form.The EFD scheme takes into account more accurately thedistribution of the source term and of the diffusion coefficientwithin a control volume. Comparison is also made with ananalytical solutions as well as with the results obtained usingother wide used methods. The EFD scheme is more accurateeven it uses a grid with fewer points. The EFD method has beenrealised using OOA.