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J. T. Ratnanather - One of the best experts on this subject based on the ideXlab platform.

  • The Stokesian flow field of an oscillatory submerged viscous jet impinging on a Planar Wall
    Proceedings of the Royal Society A: Mathematical Physical and Engineering Sciences, 2013
    Co-Authors: Anthony M. J. Davis, Jung H. Kim, Geoffrey Gunter, J. T. Ratnanather
    Abstract:

    This model of experiments on auditory sensory hair cells extends previous work via distributions on a cylindrical pipe of tangentially and normally directed oscillatory point forces, which are modified to achieve no-slip at the Wall in two stages. Starting with the pressure and vorticity jumps associated with the oscillatory pressure-driven flow upstream in the pipe, the adjustment of the interior pipe flow from its upstream complex-valued profile to its exit profile is fully included. This is essentially achieved by modifying the steps of the steady case analysis. The flow field oscillates with phase dependent on position, and the level curves of the streamfunction indicate instantaneous particle motion but not streamlines. Thus, an eddy is not indicated by the closed curve that occurs midway through the two half cycles and is due to competing forces between the inflow and outflow, particularly in the second half cycle as the fluid enters the pipe. The Wall pressure and Wall shear stress also oscillate with the non-uniformities concentrated near the origin, but are relatively damped midway through the two half cycles. Independent of the orifice location, there is a small effect of frequency on the Wall pressure and the Wall shear stress.

  • A Stokesian analysis of a submerged viscous jet impinging on a Planar Wall
    Journal of Fluid Mechanics, 2012
    Co-Authors: Anthony M. J. Davis, Jung H. Kim, C. Ceritoglu, J. T. Ratnanather
    Abstract:

    AbstractThe Wall pressure and Wall shear stress of a submerged viscous jet impinging on an infinite Planar Wall are derived. The whole creeping flow of semi-infinite extent is generated via distributions on a cylindrical pipe of tangentially and normally directed Stokeslets which are modified to achieve no-slip at the Wall in two stages. First the pressure and vorticity jumps associated with the Poiseuille flow upstream in the pipe are readily forced, and then further distributions, of zero density far upstream but with square-root density singularity at the orifice $z= h$, are added to achieve no-slip on the pipe Wall. Thus the adjustment of the interior pipe flow from its upstream parabolic profile to its exit profile is fully included in – and a major feature of – this creeping flow analysis. The maximum plane Wall pressure is always located on the axis $r= 0$, and decreases as $h$ increases to alleviate the obstruction effect of the Wall. The interaction of the inflow with the ambient fluid in the neighbourhood of $z= 0$ causes the Wall stress to rise rapidly to a maximum and then decay with the radial position of this maximum increasing as $h$ increases. This behaviour is discussed in the context of physiological experiments on auditory sensory hair cells that motivated this study.

Anthony M. J. Davis - One of the best experts on this subject based on the ideXlab platform.

  • The Stokesian flow field of an oscillatory submerged viscous jet impinging on a Planar Wall
    Proceedings of the Royal Society A: Mathematical Physical and Engineering Sciences, 2013
    Co-Authors: Anthony M. J. Davis, Jung H. Kim, Geoffrey Gunter, J. T. Ratnanather
    Abstract:

    This model of experiments on auditory sensory hair cells extends previous work via distributions on a cylindrical pipe of tangentially and normally directed oscillatory point forces, which are modified to achieve no-slip at the Wall in two stages. Starting with the pressure and vorticity jumps associated with the oscillatory pressure-driven flow upstream in the pipe, the adjustment of the interior pipe flow from its upstream complex-valued profile to its exit profile is fully included. This is essentially achieved by modifying the steps of the steady case analysis. The flow field oscillates with phase dependent on position, and the level curves of the streamfunction indicate instantaneous particle motion but not streamlines. Thus, an eddy is not indicated by the closed curve that occurs midway through the two half cycles and is due to competing forces between the inflow and outflow, particularly in the second half cycle as the fluid enters the pipe. The Wall pressure and Wall shear stress also oscillate with the non-uniformities concentrated near the origin, but are relatively damped midway through the two half cycles. Independent of the orifice location, there is a small effect of frequency on the Wall pressure and the Wall shear stress.

  • A Stokesian analysis of a submerged viscous jet impinging on a Planar Wall
    Journal of Fluid Mechanics, 2012
    Co-Authors: Anthony M. J. Davis, Jung H. Kim, C. Ceritoglu, J. T. Ratnanather
    Abstract:

    AbstractThe Wall pressure and Wall shear stress of a submerged viscous jet impinging on an infinite Planar Wall are derived. The whole creeping flow of semi-infinite extent is generated via distributions on a cylindrical pipe of tangentially and normally directed Stokeslets which are modified to achieve no-slip at the Wall in two stages. First the pressure and vorticity jumps associated with the Poiseuille flow upstream in the pipe are readily forced, and then further distributions, of zero density far upstream but with square-root density singularity at the orifice $z= h$, are added to achieve no-slip on the pipe Wall. Thus the adjustment of the interior pipe flow from its upstream parabolic profile to its exit profile is fully included in – and a major feature of – this creeping flow analysis. The maximum plane Wall pressure is always located on the axis $r= 0$, and decreases as $h$ increases to alleviate the obstruction effect of the Wall. The interaction of the inflow with the ambient fluid in the neighbourhood of $z= 0$ causes the Wall stress to rise rapidly to a maximum and then decay with the radial position of this maximum increasing as $h$ increases. This behaviour is discussed in the context of physiological experiments on auditory sensory hair cells that motivated this study.

Jung H. Kim - One of the best experts on this subject based on the ideXlab platform.

  • The Stokesian flow field of an oscillatory submerged viscous jet impinging on a Planar Wall
    Proceedings of the Royal Society A: Mathematical Physical and Engineering Sciences, 2013
    Co-Authors: Anthony M. J. Davis, Jung H. Kim, Geoffrey Gunter, J. T. Ratnanather
    Abstract:

    This model of experiments on auditory sensory hair cells extends previous work via distributions on a cylindrical pipe of tangentially and normally directed oscillatory point forces, which are modified to achieve no-slip at the Wall in two stages. Starting with the pressure and vorticity jumps associated with the oscillatory pressure-driven flow upstream in the pipe, the adjustment of the interior pipe flow from its upstream complex-valued profile to its exit profile is fully included. This is essentially achieved by modifying the steps of the steady case analysis. The flow field oscillates with phase dependent on position, and the level curves of the streamfunction indicate instantaneous particle motion but not streamlines. Thus, an eddy is not indicated by the closed curve that occurs midway through the two half cycles and is due to competing forces between the inflow and outflow, particularly in the second half cycle as the fluid enters the pipe. The Wall pressure and Wall shear stress also oscillate with the non-uniformities concentrated near the origin, but are relatively damped midway through the two half cycles. Independent of the orifice location, there is a small effect of frequency on the Wall pressure and the Wall shear stress.

  • A Stokesian analysis of a submerged viscous jet impinging on a Planar Wall
    Journal of Fluid Mechanics, 2012
    Co-Authors: Anthony M. J. Davis, Jung H. Kim, C. Ceritoglu, J. T. Ratnanather
    Abstract:

    AbstractThe Wall pressure and Wall shear stress of a submerged viscous jet impinging on an infinite Planar Wall are derived. The whole creeping flow of semi-infinite extent is generated via distributions on a cylindrical pipe of tangentially and normally directed Stokeslets which are modified to achieve no-slip at the Wall in two stages. First the pressure and vorticity jumps associated with the Poiseuille flow upstream in the pipe are readily forced, and then further distributions, of zero density far upstream but with square-root density singularity at the orifice $z= h$, are added to achieve no-slip on the pipe Wall. Thus the adjustment of the interior pipe flow from its upstream parabolic profile to its exit profile is fully included in – and a major feature of – this creeping flow analysis. The maximum plane Wall pressure is always located on the axis $r= 0$, and decreases as $h$ increases to alleviate the obstruction effect of the Wall. The interaction of the inflow with the ambient fluid in the neighbourhood of $z= 0$ causes the Wall stress to rise rapidly to a maximum and then decay with the radial position of this maximum increasing as $h$ increases. This behaviour is discussed in the context of physiological experiments on auditory sensory hair cells that motivated this study.

Serafim Kalliadasis - One of the best experts on this subject based on the ideXlab platform.

  • Wetting of a plane with a narrow solvophobic stripe
    Molecular Physics, 2018
    Co-Authors: Peter Yatsyshin, Andrew O. Parry, Carlos Rascón, Serafim Kalliadasis
    Abstract:

    We present a numerical study of a simple density functional theory model of fluid adsorption occurring on a Planar Wall decorated with a narrow deep stripe of a weaker adsorbing (relatively solvoph...

  • Wetting of prototypical one- and two-dimensional systems: Thermodynamics and density functional theory.
    The Journal of chemical physics, 2015
    Co-Authors: Petr Yatsyshin, Nikos Savva, Serafim Kalliadasis
    Abstract:

    Consider a two-dimensional capped capillary pore formed by capping two parallel Planar Walls with a third Wall orthogonal to the two Planar Walls. This system reduces to a slit pore sufficiently far from the capping Wall and to a single Planar Wall when the side Walls are far apart. Not surprisingly, wetting of capped capillaries is related to wetting of slit pores and Planar Walls. For example, the wetting temperature of the capped capillary provides the boundary between first-order and continuous transitions to condensation. We present a numerical investigation of adsorption in capped capillaries of mesoscopic widths based on density functional theory. The fluid-fluid and fluid-substrate interactions are given by the pairwise Lennard-Jones potential. We also perform a parametric study of wetting in capped capillaries by a liquid phase by varying the applied chemical potential, temperature, and pore width. This allows us to construct surface phase diagrams and investigate the complicated interplay of wetting mechanisms specific to each system, in particular, the dependence of capillary wetting temperature on the pore width.

  • thermocapillary instability and wave formation on a film falling down a uniformly heated plane
    Journal of Fluid Mechanics, 2003
    Co-Authors: Serafim Kalliadasis, E A Demekhin, Christian Ruyerquil, Manuel G Velarde
    Abstract:

    We consider a thin layer of a viscous fluid flowing down a uniformly heated Planar Wall. The heating generates a temperature distribution on the free surface which in turn induces surface tension gradients. We model this thermocapillary flow by using the Shkadov integral-boundary-layer (IBL) approximation of the Navier-Stokes/ energy equations and associated free-surface boundary conditions. We numerically construct nonlinear solutions of the solitary wave type for the IBL approximation and the Benney-type equation developed by Joo et al. using the usual long-wave approximation. The two approaches give similar solitary wave solutions up to an O(1) Reynolds number above which the solitary wave solution branch obtained by the Joo et al. equation is unrealistic, with branch multiplicity and limit points. The IBL approximation on the other hand has no limit points and predicts the existence of solitary waves for all Reynolds numbers

Gary S. Settles - One of the best experts on this subject based on the ideXlab platform.

  • Shear stress and particle removal measurements of a round turbulent air jet impinging normally upon a Planar Wall
    Journal of Aerosol Science, 2013
    Co-Authors: R.m. Young, Michael Hargather, Gary S. Settles
    Abstract:

    When a round jet of air impinges normally upon a Wall, it imposes a shear stress parallel to the Wall in all directions from the impingement point. Particle removal from that surface is assumed to be mainly due to the imposed shear stress. This shear stress has been difficult to measure directly and has, in the past, been inferred from particle removal rates. Here we make a fundamental measurement of the mean shear stress imposed upon a Planar Wall by a normally-impinging turbulent air jet using the technique of oil-film interferometry. The resulting shear–stress distribution is then compared with measured removal rates of latex microspheres from a Planar glass surface as a function of the radial distance from jet impingement normalized by the height of the nozzle exit above the surface. The particle removal experiments are carried out with sparse (few collisions) particle distributions. These experiments show that the efficiency of particle removal is directly but not linearly related to the imposed shear stress. A distinct shear stress threshold was found, below which little or no particle removal occurred.