A fundamental study of the Morphological Acceleration Factor

Long-term prediction of sediment transport and morphology has become increasingly important. One of the key issues in carrying out long-term modeling is to bridge the gap between short-term hydrodynamics varying from hours to days, and morphological changes, taking place over much longer periods. Lesser et al. (2004) and Roelvink (2006) have introduced the powerful concept of the morphological acceleration factor (Morfac) to coastal morphodynamic modeling, which potentially enables modelers to simulate morphological evolution in coastal areas at the time scales of decades. In this thesis, the effects and limits of the concept of Morfac in coastal morphodynamic modeling are studied from a 1D analytical model with unidirectional flow, and the model with numerical implementation. After linearized and non-dimensionalized, the sensitivity of the Morfac is analyzed based on investigating Froude number, sediment transport facto, friction parameter, Courant number and points per wavelength. The criteria of the Morfac is derived both from stability and accuracy. Forcing parameters such as the flow velocity magnitude is the dominant factor while the model properties like the grid size and time step play a minor role. A necessary stability criteria is derived for this specific 1D case. In the analytical and numerical models, Morfac performs better than in the Delft3D model. A strong recommendation is to further improve the numerical implementation of Delft3D which may extensively increase the value of Morfac we can use.

Subject

Delft3D
eigenvalue analysis
morphological acceleration

To reference this document use:

http://resolver.tudelft.nl/uuid:2780f537-402b-427a-9147-b8652279a83e

Part of collection

Student theses

Document type

master thesis

Rights

Files

PDF

thesis.pdf

1.11 MB

Close viewer