Numerical Modelling for Coastal Morphodynamic Evolutions
Date Issued
2009
Date
2009
Author(s)
Chiang, Yun-Chih
Abstract
Coastal morphological models are indispensable and powerful tools that allow harbor and hydraulic engineers to predict coastal bathymetry, to analyze the impact of coastal structures, and to verify the planning and design of harbors and coastal defenses. Morphological models are based on various sub-models for waves, nearshore currents, and sediment transports, coupled with the sediment transport model. The morphological model solves the sediment conservation equation to calculate bed-level evolution. The local sediment transport is first calculated by waves and nearshore currents sub-models, and the bed form evolution is then computed based on the conservation of sediment and its continual redistribution in time.he objective of the research is to develop a new numerical model of coastal morphodynamic evolutions. In the wave sub-model, the Boussinesq equation is employed to develop a series of numerical calculations to simulate the affection of wave height changes in the nearshore area. In the wave driven current sub-model, the quasi-three-dimensional numerical model of nearshore currents is developed by modified 2HD depth-averaged two-dimensional model with wave surface roller system and extended 1DV vertical velocity profile model to describe the undertows in the surf zone. In sediment transport model, there are quasi-steady, practical formulas, to predict the sediment transport rates based on modified bedload and suspended load in wave, current or wave-current interactional conditions that are characteristic of the waves asymmetry and nonlinearity. In the coastal morphological model, the bed-slope updating techniques, WNEO schemes, and 2-step with 3-time-level temporal discretization schemes are employed to remove oscillations and improve the stability with accuracy up to are developed. Finally, the integral models show good performance for LIP11D sandbar experimental data by DHI, the formation of sandbar for ideal cases, and real coastal areas with complex topography and the influence of coastal structures.
Subjects
surf zone
undertow
qusai-3d flow field
sediment transport
morphological model
Type
thesis
File(s)![Thumbnail Image]()
Loading...
Name
ntu-98-D93525006-1.pdf
Size
23.53 KB
Format
Adobe PDF
Checksum
(MD5):2d1e39eac71786279d0b9d3bddf33fc0