Numerical visualisation on the impact of setting convective velocity of outflow boundary on a parallel grid-generated flow

Abstract

This study approaches a widely used convective outflow condition for analysing turbulent flow fields with a freestream to clarify effects of the convection velocity setting. Previous studies have often used a local velocity at the outflow boundary. This study uses the setting of the outflow condition described in the previous Orlanski’s study. In this study, a two-dimensional flow induced by a parallel grid is analysed. The governing equations are spatially discretised by a second-order central difference method and integrated in the time domain using the fourth-order Runge-Kutta method. We can observe wavy profiles near the outflow boundary that vary in the streamwise direction. These wavy profiles are more evident when the local velocity is used as the convective velocity. The effect of the setting outflow velocity on the turbulence structure characterised using the second invariant of the velocity gradient tensor is also investigated.