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PRODID:-//Department of Aerospace Engineering - ECPv6.6.3//NONSGML v1.0//EN
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X-WR-CALDESC:Events for Department of Aerospace Engineering
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TZID:Asia/Kolkata
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TZOFFSETFROM:+0530
TZOFFSETTO:+0530
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DTSTART:20260101T000000
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BEGIN:VEVENT
DTSTART;TZID=Asia/Kolkata:20261103T150000
DTEND;TZID=Asia/Kolkata:20261103T170000
DTSTAMP:20261113T150234
CREATED:20261002T093202Z
LAST-MODIFIED:20261103T093048Z
UID:10000161-1793718000-1793725200@aero.iisc.ac.in
SUMMARY:Linear instabilities in modulated Taylor-Couette flows"
DESCRIPTION:The modulated Taylor-Couette flow takes place in the annular gap between two concentric cylinders\, assumed of infinite extent in the\naxial direction. Inner and outer cylinders rotate about their common axis with two independent rotation rates that are periodically modulated in time. While there exists a significant literature on the time-periodic Taylor-Couette configuration\, many investigations have addressed purely oscillating situations\, and the dynamics of the general problem where steady and oscillating flow components cooperate is not yet fully understood.\nThe radius ratio fixes the geometry and the Womersley number characterizes the modulation frequency. Assuming harmonic modulation of the cylinders’ rotation rates\, the flow dynamics is further governed by four Reynolds numbers accounting for the steady and\noscillating velocities of inner and outer cylinders.Linear instability features such as complex growth rates and Floquetmultipliers are computed with two different methods: generalized eigenvalue problems using Floquet theory and direct numerical simulations of the linearized Navier-Stokes equations. Neutral\nstability boundaries in the multi-dimensional parameter space are obtained with continuation methods.\nOur study systematically explores the effects of varying all non-dimensional control parameters.\nFor narrow-gap configurations\, low Womersley numbers and increasing oscillation amplitudes initially show destabilizing effects and  eventually lead to the emergence of multiple neutral curves\, demarcated by harmonic and subharmonic instability transitions. At higher Womersley numbers\, these transitions shift to significantly larger oscillation amplitudes. Wider-gap systems display harmonic-subharmonic bifurcations at even lower values of oscillation\namplitude\, indicating enhanced sensitivity of the flow to temporalmodulation and large curvature effects.\nOur findings analyse the fine mechanisms of the harmonic-subharmonic bifurcations\, provide a comprehensive map of the stability boundaries in modulated Taylor-Couette systems and reveal the critical role of geometry and modulation parameters in shaping the onset of instabilities.\n\nSpeaker : Benoît PIER
URL:https://aero.iisc.ac.in/event/linear-instabilities-in-modulated-taylor-couette-flows/
LOCATION:Auditorium (AE 005)\, Department of Aerospace Engineering
CATEGORIES:AE Seminar
ATTACH;FMTTYPE=image/png:https://aero.iisc.ac.in/wp-content/uploads/2026/11/Benoit-PIER.png
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