Abstract

An assessment of the performance of various parameterization alternatives for roughness lengths of momentum and water vapour was performed. The micrometereological data used in this work was measured in the Itaipu reservoir, Brazil. Four models was tested for momentum roughness length, and four for water vapour. The parameterization for horizontal momentum flux are based on the Charnock equation and generalizations while the water vapour model are based on equations proposed by Brutsaert. The four models for momentum flux produced very similar results, in terms of goodness of fit and errors, and turned out only weakly dependent on friction velocity. Already the parameterizations for water vapor produced more dispersed results, and the best parameterizations found very poorly depend on the Reynolds roughness number, or are independent of it. Both in the case of momentum and water vapour, the optimal parameter values? of each parameterization found for Itaipu are significantly larger than those reported in the literature.

Abstract

The aim of this work is to contribute to the development of a high-order accurate discretization that is entropy conserving and entropy stable both in space and in time. To do this, the general framework is based on a high-order accurate discontinuous Galerkin (dG) method in space with entropy working variables, several entropy conservative and stable numerical fluxes and an entropy conserving modified Crank-Nicolson method. We present the first results, obtained with the discretizations here proposed, for two bi-dimensional unsteady viscous test-case: the Taylor-Green vortex and the double shear layer.