A comparison of a two-dimensional depth-averaged flow model and a three-dimensional RANS model for predicting tsunami inundation and fluid forces
<p>The numerical modeling of tsunami inundation that incorporates the built environment of coastal communities is challenging for both 2-D and 3-D depth-integrated models, not only in modeling the flow but also in predicting forces on coastal structures. For depth-integrated 2-D models, in...
| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2018-09-01
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| Series: | Natural Hazards and Earth System Sciences |
| Online Access: | https://www.nat-hazards-earth-syst-sci.net/18/2489/2018/nhess-18-2489-2018.pdf |
| Summary: | <p>The numerical modeling of tsunami inundation that
incorporates the built environment of coastal communities is challenging for
both 2-D and 3-D depth-integrated models, not only in modeling the flow but
also in predicting forces on coastal structures. For depth-integrated 2-D
models, inundation and flooding in this region can be very complex with
variation in the vertical direction caused by wave breaking on shore and
interactions with the built environment, and the model may not be able to
produce enough detail. For 3-D models, a very fine mesh is required to
properly capture the physics, dramatically increasing the computational cost
and rendering impractical the modeling of some problems. In this paper,
comparisons are made between GeoClaw, a depth-integrated 2-D model based on
the nonlinear shallow-water equations (NSWEs), and OpenFOAM, a 3-D model based
on Reynolds-averaged Navier–Stokes (RANS) equation for tsunami inundation
modeling. The two models were first validated against existing experimental
data of a bore impinging onto a single square column. Then they were used to
simulate tsunami inundation of a physical model of Seaside, Oregon. The
resulting flow parameters from the models are compared and discussed, and
these results are used to extrapolate tsunami-induced force predictions. It
was found that the 2-D model did not accurately capture the important details
of the flow near initial impact due to the transiency and large vertical
variation of the flow. Tuning the drag coefficient of the 2-D model worked
well to predict tsunami forces on structures in simple cases, but this
approach was not always reliable in complicated cases. The 3-D model was able
to capture transient characteristic of the flow, but at a much higher
computational cost; it was found this cost can be alleviated by subdividing
the region into reasonably sized subdomains without loss of accuracy in
critical regions.</p> |
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| ISSN: | 1561-8633 1684-9981 |