HYDRODYNAMIC MODEL OF VESSEL-GENERATED CURRENTS

The drawdown and return currents of vessels navigating in channels hav e previously been described by empirical relations or by using physica l models. The empirical solutions are generally limited in scope to id ealized channel shapes. Physical models are unrestricted in this respe ct, but have limitations related to expense and scale effects. In this paper, vessel effects are modelled numerically. The vessel's displace ment is represented by a moving pressure field. The movement of the pr essure field is spatially varied in time, representing a vessel naviga ting along a channel. The hydrodynamics are described using the two-di mensional shallow water equations, which are modified to account for t he effects of the imposed pressure field. A Petrov-Galerkin finite-ele ment scheme using characteristic-based weighting is used to solve the governing equations. This Petrov-Galerkin test function is specificall y designed to model flow fields containing large gradients such as tho se found in the vicinity of the moving vessel. The numerical results f or return flows and water surface elevations are compared with flume r esults of vessel passages.