Turbulent structures in unsteady wall-bounded flow subject to temporal acceleration

Abstract

Direct numerical simulations (DNS) of a transient turbulent channel flow subject to constant temporal acceleration have been performed with a final Reynolds number of $\Retau=800$. The response of turbulent structures to the temporal acceleration is investigated. A significant delay in the response of turbulent flow is observed in various turbulent properties. It is found that the response of turbulent flow to temporal acceleration consists of two stages: the destruction of the initial \emph{old} turbulence, followed by the generation of \emph{new} turbulence associated with a higher $Re$ number. The \emph{new} turbulence is much stronger than the \emph{old} turbulence.