Improving the numerical modeling of river water quality by using high order difference schemes
(EN)
Stamou, AI
(EN)
A one-dimensional numerical model is presented for the description of water quality in rivers. The model is an improvement over existing models, since it involves two differential schemes of third-order truncation error (QUICK and QUICKEST), which avoid the stability problems of central difference, while remaining relatively free of the inaccuracies of numerical dispersion associated with the upwind difference scheme. The model is successfully applied to four simple, steady-state and transient water quality problems. Results show that the commonly used upwind scheme performs very poorly. The central difference scheme performs satisfactorily in steady-state implicit calculations, but not in transient problems, where it shows numerical dispersion and significant oscillations. Calculations with QUICK and QUICKEST are stable and accurate involving the minimum error and minimum level of numerical dispersion in both steady-state and transient problems.A one-dimensional numerical model is presented for the description of water quality in rivers. The model is an improvement over existing models, since it involves two differential schemes of third-order truncation error (QUICK and QUICKEST), which avoid the stability problems of central difference, while remaining relatively free of the inaccuracies of numerical dispersion associated with the upwind difference scheme. The model is successfully applied to four simple, steady-state and transient water quality problems. Results show that the commonly used upwind scheme performs very poorly. The central difference scheme performs satisfactorily in steady-state implicit calculations, but not in transient problems, where it shows numerical dispersion and significant oscillations. Calculations with QUICK and QUICKEST are stable and accurate involving the minimum error and minimum level of numerical dispersion in both steady-state and transient problems.
(EN)
