|Forty years of numerical modelling|
Cunge, J.A. (2003). Forty years of numerical modelling, in: Waterbouwkundig Laboratorium en Hydrologisch Onderzoek (Ed.) Colloquium: Numerieke oppervlaktewater modellering, mogelijkheden en beperkingen, Antwerpen 23-24 oktober 2003. pp. 1-11
In: Waterbouwkundig Laboratorium en Hydrologisch Onderzoek (Ed.) (2003). Colloquium: Numerieke oppervlaktewater modellering, mogelijkheden en beperkingen, Antwerpen 23-24 oktober 2003. Waterbouwkundig Laboratorium en Hydrologisch Onderzoek: Borgerhout, more
Modelling; Numerical models
In the presentation three main aspects of numerical modelling technology, as it has been developedand introduced in hydraulics and hydrology will be mentioned and characterised. Namely: historicaldevelopment and conditions that allowed such development; scientific and engineering aspects ofapplications, including market availability of the software and influence of the market on developments;reliability and limitations of the technology for engineering purposes. Last but not least some stillunsolved theoretically problems and difficulties in that domain will be mentioned.The presentation is engineering-oriented, stressing the applications point of view and concernsessentially deterministic modelling. The history sketched in the presentation goes back to XIXthcentury in order to show interdependence between available theory, algorithms and informatics tools,including traditional and psychological obstacles. Then the history of four generations of models usedfrom 1960 to day as well as current situation of "mass-market" for software are shortly summarised.Present situation of some confusion between application domains of correlative modelling (ArtificialNeural Networks, Genetic Algorithms) and of deterministic models is mentioned with a frontier drawnbetween two categories.A chapter is devoted to engineering applications and related use and misuse of the tools as well as tothe so called "good practice" generally admitted paradigm of modelling; it is based on four steps: setup-calibration-validation-running. Criticism of the paradigm from the point of view of current state ofknowledge and proposal for new paradigm is given.Should one believe in models results? The limitations can stem from lack of understanding of physics,lack of formulations, blind application of unsuitable schematisations, etc. What can do an engineer,who must solve a problem even if there is no "good practice" validated tool available? Example ofriver and estuary hydro- and morpho-dynamics is taken to show limitations and doubts one can haveabout the results of modelling.N.B.: Present text is accompanied by presentation of figures (transparencies) as used by the authorduring the Colloquium. This presentation is recorded as separated Power Point File that can be printedout in colours or under black and white form. Numbers of figures referred to in the text correspond toorder numbers of the transparencies in Power Point file.