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A study of the asymmetric shock reflection configurations in steady flows
10.1017/jfm.2017.280 2017-07-18 In this paper the asymmetric shock reflection configurations in two-dimensional steady flows have been studied theoretically. For an overall Mach reflection, it is found that the horizontal distance between both triple points in the Mach stem is related to th... |
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Isolated marginally stable geophysical vortices
10.1017/jfm.2017.440 2017-07-17 Long-term marginal stability of a new family of isolated oceanic vortices is analysed. Sign reversal of the radial gradient of the potential vorticity anomaly, as implied by the isolation requirement, leads to vortex unsteadiness but does not break the cohere... |
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Water entry of deformable spheres
10.1017/jfm.2017.365 2017-07-14 When a rigid body collides with a liquid surface with sufficient velocity, it creates a splash curtain above the surface and entrains air behind the sphere, creating a cavity below the surface. While cavity dynamics has been studied for over a century, this w... |
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Transport efficiency of metachronal waves in 3D cilium arrays immersed in a two-phase flow
10.1017/jfm.2017.352 2017-07-14 This work reports the formation and characterization of antipleptic and symplectic metachronal waves in 3D cilium arrays immersed in a two-fluid environment, with a viscosity ratio of 20. A coupled lattice Boltzmann–immersed-boundary solver is used. The peric... |
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Localised estimation and control of linear instabilities in two-dimensional wall-bounded shear flows
10.1017/jfm.2017.355 2017-07-13 A new framework is presented for estimation and control of instabilities in wall-bounded shear flows described by the linearised Navier–Stokes equations. The control design considers the use of localised actuators/sensors to account for convective instabiliti... |
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Drops bouncing off macro-textured superhydrophobic surfaces
10.1017/jfm.2017.306 2017-07-13 Recent experiments with droplets impacting macro-textured superhydrophobic surfaces revealed new regimes of bouncing with a remarkable reduction of the contact time. Here we present a comprehensive numerical study that reveals the physics behind these new bou... |
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Linear global stability of two incompressible coaxial jets
10.1017/jfm.2017.290 2017-07-13 The linear stability of two incompressible coaxial jets, separated by a thick duct wall, is investigated by means of both a modal and a non-modal approach within a global framework. The attention is focused on the range of unitary velocity ratios for which an... |
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Direct numerical simulation of open-channel flow over a fully rough wall at moderate relative submergence
10.1017/jfm.2017.371 2017-07-11 Direct numerical simulation of open-channel flow over a bed of spheres arranged in a regular pattern has been carried out at bulk Reynolds number and roughness Reynolds number (based on sphere diameter) of approximately 6900 and 120, respectively, for which t... |
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Turbulent jets with off-source heating
10.1017/jfm.2017.272 2017-07-11 Motivated by anomalous entrainment behaviour in cumulus clouds, Bhat et al. (Exp. Fluids, vol. 7, 1989, pp. 99–102) pioneered a laboratory experiment to study turbulent jets subjected to a volumetric heating away from the momentum source. The study concluded ... |
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Passive scalar mixing and decay at finite correlation times in the Batchelor regime
10.1017/jfm.2017.364 2017-07-11 An elegant model for passive scalar mixing and decay was given by Kraichnan (Phys. Fluids, vol. 11, 1968, pp. 945–953) assuming the velocity to be delta correlated in time. For realistic random flows this assumption becomes invalid. We generalize the Kraichna... |