Investigation and modelling on the structure of high-schmidt-number passive scalar field at a stagnation region in counter jet

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Counter jet has a higher mixing ability compared with conventional jets. Considering that this superior mixing efficiency is produced mainly by the peculiar spatial structure of the counter jet, the characteristics of the flow field, including those of an instantaneous stagnating region, were studied experimentally for a plane counter jet. First of all, a technique for evaluating the instantaneous stagnation point quantitatively was devised. Then statistical features were found on the fluctuation field of the instantaneous stagnation point after applying this method to experimental data obtained by PIV.Furthermore, the flip-flop jet which has a similar jet meandering as the counter jet was investigated numerically in order to study the effect of the jet wandering on the development of the passive scalar issued from the nozzle. It was found that the jet oscillation frequency could be controlled externally without changing the nozzle geometry.