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arXiv · 2508.20636

Streak generation in viscosity-stratified wall-bounded flows

Anagha Madhusudanan·Simon J. Illingworth·Rama Govindarajan
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Abstract

Streamwise elongated flow structures, or streaks, dominate wall-bounded flows. We show that the renowned lift-up mechanism, that generates streaks, is significantly altered by viscosity stratification. We additionally identify a novel pathway for streak generation: the viscosity-stratified lift-up mechanism. The competition and cooperation of the streaks generated by these mechanisms provides an explanation for trends in viscosity-stratified Poiseuille flows, and remarkably, the opposing trends in Couette flows as well. Our theoretical observations are substantiated by numerical experiments.

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Anagha Madhusudanan, Simon J. Illingworth, Rama Govindarajan. 2025-08-28. Streak generation in viscosity-stratified wall-bounded flows. https://arxiv.org/abs/2508.20636

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