MODELLING THE HORIZONTAL DISTRIBUTION OF ALGAE IN A WATER SUPPLY RESERVOIR

摘要

A 3D numerical model was used to calculate the wind-induced accumulation of algaernin Eglwys Nynydd, a water supply reservoir in Wales. The model solved the Navier-rnStokes equations for the water velocities using the SIMPLE method to calculate thernpressure. Two turbulence models were tested: a zero-equation model and the k-ernmodel. An unstructured non-orthogonal 3D grid with hexahedral cells was used. Therndistribution of the algae Microcystis was calculated by solving the transientrnconvection-diffusion equation for algae concentration, based on the modelled waterrnflow field. The numerical model included algorithms for calculating the growth rate ofrnalgae and simulating the response of the algae to changes in underwater light. Thernmodel was validated by comparing the horizontal distribution pattern produced byrnsimulation with those recorded during a field survey of surface concentrations. Thernresults demonstrated reasonable agreement, particularly when using the k-ernturbulence model.