A linear stability investigation is undertaken on the two-dimensional flow that develops in a channel whose walls are coated with superhydrophobic material. The surfaces modeled as classical slip surfaces, exploiting Navier condition imposed walls. Both symmetric and asymmetric considered, whereby linearized of determined via an Orr–Sommerfeld normal-mode approach. In both instances, application establishes significant stabilizing effect increases critical Reynolds number associated onset...

We consider the flow induced by a sphere, contained in an otherwise quiescent body of fluid, that is suddenly imparted with angular momentum. This classical problem known to exhibit finite-time singularity boundary-layer equations, due viscous boundary layer, sudden rotation, colliding at sphere's equator. this from perspective post-collision dynamics, showing collision gives rises radial jet headed swirling toroidal starting vortex pair. The propagates away sphere and, doing so, loses jet,...

We investigate the effects of wall suction and injection on Chemical Vapour Deposition (CVD), a microfabrication process in which gas mixture is pumped into reactor flows over heated reactant porous surface to chemically deposit thin film. Regular cohesive film growth requires that laminar flow be maintained. The energy balance with for temperature dependence parameter $ϵ<0$ leads increasing total mechanical due reducing production dissipation suction; $ϵ>0$ there stabilization effect...

A numerical study on the effect of surface slip flow in a constricted channel is presented, with aim exploring use to control separation. Our focus two-dimensional over bump, fixed aspect ratio, upon which Robin-type boundary condition imposed. When walls are fully no-slip, such known develop region separation behind at sufficiently large Reynolds numbers. The bubble dynamics occurring bump investigated, for numbers $2000$ and $4000$ . It shown that (i) attenuates intensity as it diminishes...

Surface slip, characterized by a slip length, $\ensuremath{\lambda}$, suppresses flow separation induced Gaussian-shaped deformations on flat plate. Bumps generate more intense regions of reversed than gaps, requiring larger $\ensuremath{\lambda}$ to inhibit separation. The study extends double-bump configurations, where the distance between bumps establishes either stabilizing effect or nonlinear oscillatory flow. However, increasing ultimately this phenomenon and eliminates all pockets separated

The unsteady flow due to a sphere, immersed in quiescent fluid, and suddenly rotated, is paradigm for the development of boundary layers their collision. Such collision arises when on surface sphere are advected towards equator, where they collide, serving generate radial jet. We present first particle image velocimetry measurements this process, resulting starting vortex Coupled with new computations, we demonstrate that post-collision steady detaches smoothly from sphere’s surface,...

Abstract We consider the behaviour of flow within a fluid-filled torus when there is sudden change in rotation rate torus. Experimental work on this problem by Madden &amp; Mullin ( J. Fluid Mech. , vol. 265, 1994, p. 217) demonstrated with rich and complex dynamics. In particular, planar (top-down) visualisation images show well-defined laminar band at both inner outer bend toroidal pipe. Hewitt et al. 688, 2011, pp. 88–119) existence finite-time singularities resulting viscous boundary...

We present results of a study on the roughness-induced receptivity boundary layer that exists in flow due to rotating sphere. Our approach exploits computational methodology allows us capture full range fundamental fluid physics arises from early collision layers sphere’s rotation development radial jet and subsequent instabilities spatially temporally developing flow. demonstrate can exhibit transient convective instability form spiral vortex, but ultimately returns laminar state....

A computational study shows that the flow induced by a sphere rotating in an otherwise quiescent fluid is convectively unstable to spiral vortices, which once are swept down through sphere's boundary layer and then out into radial jet emanates from equator.

A new model of the steady boundary layer flow around a rotating sphere is developed that includes widely observed collision and subsequent eruption layers at equator. This derived following Segalini &amp; Garrett ( J. Fluid Mech. , vol. 818, 2017, pp. 288–318) asymptotic approach for large Reynolds numbers but replacing Smith Duck Q. Appl. Maths 30, issue 2, 1977, 143–156) correction with higher-order version Stewartson Grenzschichtforschung/Boundary Layer Research 1958, 59–71. Springer)...

Abstract The effect of slip along a Gaussian-shaped gap deformity, located about fixed position on the lower wall two-dimensional channel, is numerically investigated. Two deformations are modelled, with dimensions sufficient to generate localised pockets reversed flow when channel walls fully no-slip. Reynolds number flow, based half-width, 4000 for this investigation. two have same depth, 𝑑, but different widths, 𝜎, leading wide an aspect ratio 𝜂 = 𝑑/𝜎 0.4 and narrow 0.8. establishes...

Abstract Significance bills itself as “a magazine about statistics and data science, written by experts for everyone”. But too few of its featured are women, an analysis Karen Lamb, Jessica Kasza, Sophie Calabretto, Rushani Wijesuriya Linda McIver shows