Tidal Averaging Of A Two Layer Particle Transport Model

Abstract

The mixing process of dissolved matter in shallow water can be modelled using a stochastic particle model. The results of a simulation with a particle model are equivalent to the results of the more common model in which the advection-diffusion equation is solved numerically. The particle model is applied to a two layer transport model of the Dutch coastal zone. For long term computations these tidal models are very time consuming. Because of the periodicity of the system, tidal averaging can be used to derive a tidally averaged particle model. The averaged particle model can again lie implemented easily and can be used for long term simulations. The averaging technique in a two dimensional model of the Dutch Coastal zone has already been implemented succesfully. Since the scales in the vertical direction (only several meters in shallow water) are different from the horizontal scales (several hundred meters to some kilometers), extension to the threedimensional case is not straightforward. Therefore in this paper a two-layer averaged model is derived. A software tool has been developed to determine the various coefficients of the tidally averaged model automatically by using the input of the tidal transport model during one tidal cycle. The averaged model has been implemented and tested extensively. In this paper we show some examples of the results.