What is it about?

The present work is part of a research program dedicated to the study of large-scale coherent structures, which form in channels comprising narrow flow regions adjacent to relatively larger regions. These flow structures can be defined as quasi-periodic vortices that are convected along the flow. Here, we show the presence, even in laminar flows, of the coherent structures in flow between parallel fins; we obtain the onset conditions for their formation and we characterize their features as functions of geometrical and dynamical parameters.

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Why is it important?

The large-scale coherent structures are important flow phenomena as they transport fluid, momentum and heat much more efficiently and over much larger distances than turbulent diffusion, thus reducing velocity and temperature differences and enhancing heat transfer in the narrow regions. Many applications of engineering interest, including nuclear reactor thermal-hydraulics (rod bundles), river floodplain hydraulics and cooling of electronic devices (axial fins), involve flow configurations formed by narrow flow regions neighbouring larger ones.


Documenting the formation of large scale coherent structures in flows between axial fins will allow the use of their beneficial heat transfer enhancement in the cooling of electronic devices. The fact that they are present even in laminar flows, opens the perspective of exploiting these phenomena in microchannel cooling applications.

Dr Mohamed Sadok Guellouz
University of Carthage

Read the Original

This page is a summary of: An experimental study of the inception of large-scale structures in laminar flow through two parallel fins, Physics of Fluids, November 2022, American Institute of Physics,
DOI: 10.1063/5.0123549.
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