ABSTRACT RESUMEN A partir del programa original de Rogallo (1981) y del derivado po) Lee y Reynolds (1985)) se ha elaborado un programa de simulación directa de la turbulencia homogénea bidimensional. Este programa se ha usado para medir la velocidad de retorno a la isotropía en un flujo turbulento homogéneo inicialmente no isotrópico y para deducir e l efecto de los esfuerzos normales sobre la turbulencia bidimensional isotrópica. Los resultados obtenidos han permitido observar que (1) sí que existe retorno a la isotropía cuando se relaja u4 campo inicialmente no isotrópico y se mantiene la bidimensionalidad y (2) la deformación de un campo bidimensional isotrópico no introduce ninguna anisotropía. SUMMARY The effects of anisotropy on the decay of two-dimensional turbulence have been studied using a computer code for the direct numerical simulation of homogqneous two-dimensional turbulence, developed from the original code of Rogallo (1981) and the subsequent code of Lee and Reynolds (1985). Also, the effects of normal strain on isotropic two-dimensional turbulence have been established. Results show that (1) it exists return to isotropy during the relaxation process of an initially non isotropic, two-dimensional, homogeneous flow and (2) the deformation of an isotropic two-dimensionalfield by means of a plane strain does not droduce any anisotropic effect.

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