Finite element-fractional steps solution of the 3-D coastal circulation model

The mathematical model for the nearly horizontal circulation due to wind, tides and density gradients in 3-D coastal areas is solved by a combined use of the method of finite elements and the integration in fractional steps. The discretisation of the flow domain is achieved through a system of 1-D finite elements over the depth, z, and 2-D finite elements in x?y space. The differential operators of the momentum equations in x and y, are split and integrated separately in z and x?y dimensions. The method is an extension of a previously presented approach combining finite differences and expansion in series. The application refers to the wind induced circulation in the 3-D coastal basin of Thessaloniki Bay.