抄録
In this study unsteady simulations of the flow through and after a 90° pipe bend has been performed by Large Eddy Simulations (LES). In the passenger car engine there is an abundance of pipes and pipe bends. Since pipes and bends are often situated upstream of important engine components the flow in these needs to be well predicted. This entails that there is a need for accurate pipe flow simulations in order to ensure that the inflow conditions, to the e.g. cylinders or turbocharger, are as close to the experimental values as possible. The flow field is further studied by the use of Proper Orthogonal Decomposition (POD) and Dynamic Mode Decomposition (DMD). It has been found that there is a low frequency oscillation in the strength of the alternately dominant dean vortex at the exit of the pipe bend. This phenomenon is analysed and the mechanism for it is discussed.
