Hydrostatic and non-hydrostatic modeling of internal waves (2006)

by Bridget M. Wadzuk and Ben R. Hodges

Citation: Wadzuk, B.M., and B.R. Hodges (2006), “Hydrostatic and non-hydrostatic modeling of internal waves,” submitted to Journal of Engineering Mechanics, (March, 2006).

Abstract

Internal waves are inherently non-hydrostatic, however, they are frequently resolved in three-dimensional (3D) hydrostatic lake and coastal ocean models. Quantitative comparison of laboratory scale, hydrostatic and non-hydrostatic formulations of the Centre for Water Research Estuary and Lake Computer Model (CWR-ELCOM) provide insight into the differences and similarities between these models of internal waves. As expected, the hydrostatic model cannot replicate the degeneration of a basin-scale wave into a train of solitary waves, whereas a non-hydrostatic model adequately represents the down-scaling of energy. However, the hydrostatic model produces a nonlinear traveling bore that has similar energy magnitude to the solitary wave train in the non-hydrostatic.model; this allows us to argue that the hydrostatic approximation may provide a suitable base model for future development of subgrid-scale non-hydrostatic internal wave closure schemes. Furthermore, it is shown that modeling strongly nonlinear waves with primitive-variable equations is relatively robust, however, weakly nonlinear waves, affected by viscous damping, are more difficult to represent and the interplay between dissipation and wave steepening is a smaller-scale phenomena than steepening and wave dispersion.

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©2006 Ben R. Hodges	• last updated April 19, 2006	• UT • College of Engineering • Dept of Civil Engineering • CRWR • EFM Home •