Global Instabilities in Wall Jets
AbstractA wall jet, produced when fluid is blown tangentially across a flat surface, occurs in various applications. The linear instability of this flow has been studied under the assumption of locally...
View ArticleTransient growth and why we should care about it
AbstractThe phrases ‘transient growth’ and ‘non-normality’ have become common parlance in fluid mechanics nowadays. We present these ideas with a simple two-dimensional system, to enable the reader to...
View ArticleGlobal instabilities in diverging channel flows
AbstractA global stability study of a divergent channel flow reveals features not obtained hitherto by making either the parallel or the weakly non-parallel (WNP) flow assumption. A divergent channel...
View ArticleThe hydraulic jump and the shallow-water equations
AbstractThis is a study of the shallow-water equations in the context of standing hydraulic jumps in a planar geometry. The inviscid solutions are reviewed and it is demonstrated that the commonly used...
View ArticleVortex Filament and Global Instability Analysis of the Crow Mode
AbstractAircraft trailing vortices and their wakes are important to understand in order to shorten the minimum aircraft distances for safe operation in commercial flights. The mechanisms of wake...
View ArticleLaminar Separation Bubbles in Two-Dimensional Straight-Diverging-Straight...
AbstractGeometries with sudden expansion have been a subject of study for decades now, owing to its engineering applications. While attention has been lavished on flow through symmetric channels with...
View ArticleRolling motion in moving droplets
AbstractDrops moving on a substrate under the action of gravity display both rolling and sliding motions. The two limits of a thin sheet-like drop in sliding motion on a surface, and a spherical drop...
View ArticleNumerical study of laminar, standing hydraulic jumps in a planar geometry
AbstractWe solve the two-dimensional, planar Navier-Stokes equations to simulate a laminar, standing hydraulic jump using a Volume-of-Fluid method. The geometry downstream of the jump has been designed...
View ArticleMinimal Modeling for Passive Flow Control via a Poro-elastic Coating
AbstractMinimal models are obtained for vortex-shedding, both from a smooth aerofoil, and from an aerofoil coated with a porous layer of flow-compliant feather-like actuators. The latter is a passive...
View ArticleInviscid instability of two-fluid free surface flow down an incline
AbstractThe inviscid temporal stability analysis of two-fluid parallel shear flow with a free surface, down an incline, is studied. The velocity profiles are chosen as piecewise-linear with two limbs....
View ArticleClustering of heavy particles in vortical flows: a selective review
Abstract Heavy particles in a turbulent flow tend to leave regions of high vorticity and cluster into regions of high strain. The consequences of such clustering have been studied in a variety of...
View ArticleCloud Micro atlas
AbstractWe begin by outlining the life cycle of a tall cloud, and then briefly discuss cloud systems. We choose one aspect of this life cycle, namely, the rapid growth of water droplets in icefree...
View ArticleUnderstanding Transmission Dynamics of COVID-19-Type Infections by Direct...
AbstractThe transmission dynamics of highly contagious respiratory diseases like COVID-19 (through coughing/sneezing) is an open problem in the epidemiological studies of such diseases (Bourouiba,...
View ArticleBoundary Layer Stability and Transition to Turbulence
AbstractThis article describes Roddam Narasimha’s work on the instability of laminar flow and the subsequent transition to turbulence in boundary layers. I try to explain to the reader why this problem...
View ArticleSinking flux of particulate organic matter in the oceans: Sensitivity to...
AbstractThe sinking of organic particles produced in the upper sunlit layers of the ocean forms an important limb of the oceanic biological pump, which impacts the sequestration of carbon and resupply...
View ArticleWhy a falling drop does not in general behave like a rising bubble
AbstractIs a settling drop equivalent to a rising bubble? The answer is known to be in general a no, but we show that when the density of the drop is less than 1.2 times that of the surrounding fluid,...
View ArticleDynamics of an initially spherical bubble rising in quiescent liquid
AbstractThe beauty and complexity of the shapes and dynamics of bubbles rising in liquid have fascinated scientists for centuries. Here we perform simulations on an initially spherical bubble starting...
View ArticleShear flow stability: the physics of spatial development and viscosity...
AbstractWe describe how a nonparallel shear flow presents completely new physics in its stability behaviour, totally absent in a very close parallel shear flow. Roddam Narasimha’s insight in this...
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