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Numerical diffusion in stratified lake models
by Bernard Laval, Ben R. Hodges and Jörg Imberger
Citation: Laval, B., B.R. Hodges, and J. Imberger, “Numerical diffusion in stratified lake models,” Fifth International Symposium on Stratified Flows, Vancouver, Canada, July 7-11, 2000, pp. 343-348.
Abstract
Three-dimensional numerical models that solve the shallow water equations on a coarse fixed-grid, are limited in their ability to predict internal wave evolution, by the cumulative effects of numerical diffusion. Numerical diffusion of the metalimnion alters the internal response of the basin, and precludes simulations on seasonal to annual time scales. The discrete solution of the equations of motion leads to unintentional smoothing of advected gradients, which irreversibly increases the thickness of the metalimnion. The hydrostatic approximation exacerbates numerical diffusion by steepening internal basin-scale waves due to nonlinear effects until limited by numerical diffusion and dissipation. This steepening enhances horizontal gradients at the wave front which increases numerical diffusion locally, leaving a diffused metalimnion in the wake of the wave front. A method for correcting the numerical diffusion of mass based on conservation of background potential energy is proposed.
Note the conference paper above was preliminary work for a peer-reviewed journal paper <more info>
| ©2003 Ben R. Hodges | • last updated August 16, 2003 |
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