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You are invited to hear
a talk by
Tuesday, November 15 2-3 p.m.
Food Processing Technology Building Conference Room 103, NARA complex
About this talk
Although jet flow is one of the simplest configuration in fluid mechanics, its dynamic behaviour is still not well understood. The mixing characteristics of ambient fluid and jet fluid is important in many engineering applications such as combustion engines, jet in cross flow, pollutant spreading over air, and ocean contamination. In compression ignition (e.g. diesel) engines, transient injections of fuel jets enhance mixing of fuel and air to control the ignition event which is critical for efficient heat conversion and pollutant reduction. In understanding the jet flow field, the concept of self-similarity is widely used for understanding of turbulent flow such as jets, wakes, and mixing layers. If the self-similarity holds, all the scaled fluid properties are represented by scaled coordinates. For example in a steady-state turbulent round jet, all the velocity statistics scaled by its centerline axial velocity are the functions of the scaled radius, typically radius over axial location. The self-similarity assumption is made when modelling the unsteady jet, while this assumption had not been fully justified. Direct numerical simulation of stopping jet was performed with multiple realizations, and the self-similarity assumption is tested. Furthermore, we developed a rigorous analysis of self-similar unsteady jet whose model is validated with DNS data set. Lastly, the self-similarity of new passive scalar, fluid age, is investigated with steady state jet. The characterization of fluid age can lead to the development of combustion model with application to internal combustion engines.
About Dr. Shin
