The Experts below are selected from a list of 273 Experts worldwide ranked by ideXlab platform

Anders Peter Andersen - One of the best experts on this subject based on the ideXlab platform.

  • Structure of a steady Drain-Hole vortex in a viscous fluid
    Journal of Fluid Mechanics, 2010
    Co-Authors: Lasse Bøhling, Anders Peter Andersen, David Fabre
    Abstract:

    We use direct numerical simulations to study a steady bathtub vortex in a cylindrical tank with a central Drain-Hole, a flat stress-free surface and velocity prescribed at the inlet. We find that the qualitative structure of the meridional flow does not depend on the radial Reynolds number, whereas we observe a weak overall rotation at a low radial Reynolds number and a concentrated vortex above the Drain-Hole at a high radial Reynolds number. We introduce a simple analytically integrable model that shows the same qualitative dependence on the radial Reynolds number as the simulations and compares favourably with the results for the radial velocity and the azimuthal velocity at the surface. Finally, we describe the height dependence of the radius of the vortex core and the maximum of the azimuthal velocity at a high radial Reynolds number, and we show that the data on the radius of the vortex core and the maximum of the azimuthal velocity as functions of height collapse on single curves by appropriate scaling.

  • Anatomy of a bathtub vortex.
    Physical review letters, 2003
    Co-Authors: Anders Peter Andersen, Tomas Bohr, B. Stenum, J. Juul Rasmussen, Benny Lautrup
    Abstract:

    We present experiments and theory for the ‘‘bathtub vortex,’’ which forms when a fluid Drains out of a rotating cylindrical container through a small Drain Hole. The fast down-flow is found to be confined to a narrow and rapidly rotating ‘‘Drainpipe’’ from the free surface down to the Drain Hole. Surrounding this Drainpipe is a region with slow upward flow generated by the Ekman layer at the bottom of the container. This flow structure leads us to a theoretical model similar to one obtained earlier by Lundgren [J. Fluid Mech. 155, 381 (1985)], but here including surface tension and Ekman upwelling, comparing favorably with our measurements. At the tip of the needlelike surface depression, we observe a bubble-forming instability at high rotation rates.

Brian Fidler - One of the best experts on this subject based on the ideXlab platform.

David Fabre - One of the best experts on this subject based on the ideXlab platform.

  • Structure of a steady Drain-Hole vortex in a viscous fluid
    Journal of Fluid Mechanics, 2010
    Co-Authors: Lasse Bøhling, Anders Peter Andersen, David Fabre
    Abstract:

    We use direct numerical simulations to study a steady bathtub vortex in a cylindrical tank with a central Drain-Hole, a flat stress-free surface and velocity prescribed at the inlet. We find that the qualitative structure of the meridional flow does not depend on the radial Reynolds number, whereas we observe a weak overall rotation at a low radial Reynolds number and a concentrated vortex above the Drain-Hole at a high radial Reynolds number. We introduce a simple analytically integrable model that shows the same qualitative dependence on the radial Reynolds number as the simulations and compares favourably with the results for the radial velocity and the azimuthal velocity at the surface. Finally, we describe the height dependence of the radius of the vortex core and the maximum of the azimuthal velocity at a high radial Reynolds number, and we show that the data on the radius of the vortex core and the maximum of the azimuthal velocity as functions of height collapse on single curves by appropriate scaling.

Naoto Yokoyama - One of the best experts on this subject based on the ideXlab platform.

  • Sequential transitions of bathtub vortex flow
    Physical Review Fluids, 2017
    Co-Authors: Jiro Mizushima, Kazuki Abe, Naoto Yokoyama
    Abstract:

    A bathtub vortex has been found to be induced autonomously by instability of the steady symmetric flow if the bathtub has a rectangular cross section. A new study finds that the vortex axis deviates from the center of the Drain Hole by further instability and even further instability causes temporal oscillation of the vortex.

  • Bathtub vortex induced by instability.
    Physical review. E Statistical nonlinear and soft matter physics, 2014
    Co-Authors: Jiro Mizushima, Kazuki Abe, Naoto Yokoyama
    Abstract:

    The driving mechanism and the swirl direction of the bathtub vortex are investigated by the linear stability analysis of the no-vortex flow as well as numerical simulations. We find that only systems having plane symmetries with respect to vertical planes deserve research for the swirl direction. The bathtub vortex appearing in a vessel with a rectangular cross section having a Drain Hole at the center of the bottom is proved to be induced by instability when the flow rate exceeds a threshold. The Coriolis force is capable of determining the swirl direction to be cyclonic.

Vienne Patrick - One of the best experts on this subject based on the ideXlab platform.

  • Simplified wound care and earlier wound recovery without closed suction Drainage in elective total hip arthroplasty. A prospective randomized trial in 100 operations
    2018
    Co-Authors: Dora Claudio, Von Campe Arndt, Mengiardi Bernhard, Koch Peter, Vienne Patrick
    Abstract:

    Introduction: Evidence to support or refute closed suction Drainage (CSD) in primary total hip replacement (THR) is not conclusive. Our anecdotical experience was that persistent ooze from the Drainage Hole often delayed wound recovery. We hypothesized that, without CSD, wound care would be simplified without short or long term disadvantage. Materials and methods: Hundred patients scheduled for primary THR were randomly assigned for CSD or non-Drainage. Drains were withdrawn at day2. Pain, wound hematoma, number of dressing changes, time of persistent discharge from the operation site (skin incision and Drain Hole), total blood loss and number of blood transfusions were prospectively recorded. Hip function, presence of heterotopic ossifications (HTO) and complications were recorded at a follow visit 1year after surgery. Results: Wound sites managed without CSD needed significantly less wound dressings (P