Turbulent flow simulations at higher Reynolds numbers

Abstract

This thesis presents recent advancements in direct numerical simulations of bluff body wake flows. The flow around a circular cylinder without and with special fairings have been studied, and the effect of boundary conditions compared with what is used in physical experiments. The flow around a 45 inclined 6:1 prolate spheroid have been studied for a broad range of Reynolds numbers ranging from 4000 to 16 000 based on the minor diameter of the spheroid. During this range of Reynolds numbers there is a transition from a steady, symmetric, laminar flow to a highly turbulent and asymmetric flow. Several interesting flow phenomena have been investigated in details. In addition to the flow investigations the present thesis present developments in simulation tools and mesh design which were neccesary in order to conduct the largest simulations in this thesis, that is the inclined prolate spheroid at Reynolds number 16000. The grid used contained around 8.4 billion (109) grid cells.