Auto-generation by interaction of weak eddies
Manu Goudar Vishwanathappa (TU Delft - Mechanical Engineering)
Wim-Paul Breugem (TU Delft - Mechanical Engineering)
Yoshi Jodai (National College of Technology)
Gerrit Elsinga (TU Delft - Mechanical Engineering)
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Abstract
For channel flow, we explore how the interaction of weak eddies produces additional eddies by means of auto-generation. This is done by DNS of two eddies with different initial strengths, initial sizes and initial stream-wise spacing between them. The numerical procedure followed is similar to Zhou et al[1]. The two eddies merge into a single stronger eddy when a larger upstream and a smaller downstream eddy are placed within a certain initial stream-wise separation distance. Subsequently, the resulting stronger eddy is observed to auto-generate new eddies. The non-merging cases with small initial stream wise separation also auto-generate. The auto-generation is characterized by a rapid lift-up of an initial eddy, which blocks the incoming flow and leads to shear- layer roll-up and formation of a new eddy. The same sequence of events is observed in a fully developed turbulent boundary layer[2].