Abstract
In this study, the flow dynamics of intrusive gravity currents past a bottom-mounted obstacle were investigated using highly resolved numerical simulations. The propagation dynamics of a classic intrusive gravity current was first simulated in order to validate the numerical model with previous laboratory experiments. A bottom-mounted obstacle with a varying non-dimensional height of D~ = D/ H, where D is the obstacle height and H is the total flow depth, was then added to the problem in order to study the downstream flow pattern of the intrusive gravity current. For short obstacles, the intrusion re-established itself downstream without much distortion. However, for tall obstacles, the downstream flow was found to be a joint effect of horizontal advection, overshoot-spring back phenomenon, and associated Kelvin-Helmholtz instabilities. Analysis of the numerical results show that the relationship between the downstream propagation speed and the obstacle height can be subdivided into three regimes: (1) a retarding regime (D~ ≈ 0–0.3) where a 30 % increase in obstacle height leads to a 20 % reduction in propagation speed, simply due to the obstacle's retarding effect; (2) an impounding regime (D~ ≈ 0.3–0.6) where the additional 30 % increase in obstacle height only leads to a further (negligible) 5 % reduction in propagation speed, due to the accelerating effect of upstream impoundment and downstream enhanced mixing; and (3) a choking regime (D~ ≈ 0.6–1.0) where the propagation speed is dramatically reduced due to the dominance of the obstacle's blocking effect. The obstacle thickness was found to be irrelevant in determining the downstream propagation speed at least for the parameter range explored in this study. The present work highlights the significance of topographic effects in stratified flows with horizontal pressure forcing.
Recommended Citation
J. Zhou and S. K. Venayagamoorthy, "Numerical Simulations of Intrusive Gravity Currents Interacting with a Bottom-mounted Obstacle in a Continuously Stratified Ambient," Environmental Fluid Mechanics, vol. 17, no. 2, pp. 191 - 209, Springer, Apr 2017.
The definitive version is available at https://doi.org/10.1007/s10652-016-9454-3
Department(s)
Civil, Architectural and Environmental Engineering
Keywords and Phrases
Buoyancy forces; Intrusive gravity currents; Numerical simulations; Obstacle effect; Propagation speed; Stratified flows
International Standard Serial Number (ISSN)
1573-1510; 1567-7419
Document Type
Article - Journal
Document Version
Citation
File Type
text
Language(s)
English
Rights
© 2025 Springer, All rights reserved.
Publication Date
01 Apr 2017
Comments
National Science Foundation, Grant 1151838