Conferences - Seminars

  Friday 16 February 2018 09:15 - 10:15 MED 0 1418

Beyond DNS resolution: Resolving transport phenomena in laminar jet impingement

By Dr.-Ing. Dr. rer. pol. Wilko Rohlfs, RWTH Aachen University

Abstract :
Impinging jets are central to many industrial processes and applications, and as such have been investigated extensively in the past century. Today’s research focusses on turbulent jet impingement mainly, including direct numerical simulations of jet impingement (with Reynolds numbers of around 10,000). However, the miniaturization of electrical components and its increase in power density (up to 200W/cm²), especially in the electro-mobility sector, calls for localized cooling techniques. Dissipating heat from small hot-spots of a few millimeter size leads back to laminar flow conditions.
This research seminar demonstrates that a precise analysis and evaluation of laminar jet impingement can still yield new insights into the governing physical mechanisms. The seminar will be structured in two sections. First, the influence of local flow acceleration in the stagnation zone will be discussed; explaining the root cause for an increasing Nusselt number in flow direction within the stagnation zone. The second section demonstrates how new physically-based correlations for the Nusselt number in the stagnation zone can be obtained from a precise post-processing of numerical simulation results. The seminar ends with an outlook for further studies that grounds on the knowledge obtained before.

Bio :
Dr. Rohlfs is a researcher and research group leader in the field of heat and mass transfer and fluid dynamics at RWTH Aachen University. He received his PhD in mechanical engineering for his work on inverted and electrified falling liquid films in 2015. Further research foci of Dr. Rohlfs are the fundamentals of jet impingement as used for cooling of small-size electric devices (power electronics or microchips). In his research group, he applies experimental, numerical and theoretical methods. In 2014 he received a second PhD in economics for his work on modelling investment decisions under uncertainty in the electricity sector.

Organization IGM

Contact Prof. François Gallaire IGM - LFMI

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