Development of A Fully Coupled, Unstructured Grid, Coastal Morphodynamic Model System

Zheng, P (2017) Development of A Fully Coupled, Unstructured Grid, Coastal Morphodynamic Model System. PhD thesis, University of Liverpool.

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Abstract

A new fully coupled, unstructured grid, three-dimensional coastal morphodynamic model system is developed in this research. Based on two original independent models, i.e. the original unstructured-grid version of the third generation spectral wave model Simulating WAves Nearshore (UnSWAN) and the original Finite Volume Coastal Ocean Model (FVCOM), the development of this model system is achieved by accomplishing the following procedures: Coupling UnSWAN with FVCOM to enable the full representation of the wave-current interaction in the nearshore region, by building a new wave-current coupling scheme based on the vortex-force (VF) approach to represent the wave-current interaction and developing a new coupling module to facilitate the communication between UnSWAN and FVCOM in the parallel computing and realise the model coupling procedure. A GLS turbulence model is also modiﬁed to better reproduce wave-breaking generated turbulence, together with a roller transport model to account for the eﬀects of surface wave roller. An alternative wave model based on Mellor et al. is also implemented in the present model system. The original advection-diﬀusion (AD) module is modiﬁed for the representation of particle suspension and subsequent transport under the combined ﬂows. In this module, the contribution of wave-induced stokes drift to particle transport is included which is absent in the original FVCOM model. A new bed load transport module based on the SANTOSS formulae is built to represent various processes within the oscillatory boundary layer. Based on the semi-unsteady "half-cycle" concept, this SANTOSS formulae distinguish the sediment transports during the positive “crest” and the negative “trough” half-cycles and have the advantages over the traditional steady ’equilibrium’ transport formula that many wave-induced unsteadiness eﬀects are included, including the wave asymmetry, sediment grain size eﬀects and etc. Finally, the wave, circulation, suspended sediment and bed-load transport modules are integrated into the fully coupled, three-dimensional coastal morphodynamic model system, in which a sediment continuity (Exner) equation is also included to resolve the morphology evolution.

Item Type:	Thesis (PhD)
Divisions:	Faculty of Science and Engineering > School of Engineering
Depositing User:	Symplectic Admin
Date Deposited:	21 Aug 2018 08:10
Last Modified:	16 Jan 2024 17:21
DOI:	10.17638/03020596
Supervisors:	Li, Ming Wolf, Judith Burrows, Richard Thorne, Peter
URI:	https://livrepository.liverpool.ac.uk/id/eprint/3020596