September 19, 2016

Structures and dynamics in the wakes of sliding bubbles

  • Donnelly B.
  • Nolan K.

Structures and dynamics in the wakes of sliding bubbles An experimental investigation is reported for the flow structures in the wake of an air bubble sliding under an inclined surface in quiescent water. Time-resolved Particle Image Velocimetry (PIV) is used to study the wakes of sliding bubbles for a range of measurement planes, bubble diameters and surface inclination angles. Additionally, key aspects of the bubble's motion are measured simultaneously using a novel method that accounts for the motion of the bubbles interface. Thus, vortex shedding may be linked to changes in the bubble shape and path. Analysis of the measured velocity and vorticity fields reveals a wake structure consisting of a near wake that moves in close proximity to the bubble, shedding vorticity at the inversion points of the bubble path. Downstream of the bubble in the far wake, these structures evolve into asymmetrical, oppositely-oriented hairpin vortices that are generated in the near wake. These hairpin vortices bear similarities to those observed behind freely rising bubbles and near-wall bluff bodies and are found to cause significant motion of the bulk fluid. This bulk fluid motion has the potential to offer significant convective cooling of adjacent heated surfaces, such as submerged electronics components.

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Recent Publications

August 28, 2024

Hybrid GMM-UBM and SVM based systems for text-independent speaker verification in noisy environment

  • Carvalho D.
  • Cavalcanti G.
  • Pinheiro H.
  • Sijbers J.
  • Tsang I.
  • Tsang I.

This paper proposes a hybrid Gaussian Mixture Model-Universal Background Model (GMM-UBM) based speaker verification system for mobile devices in variable noisy environments. We applied a Support Vector Machine (SVM) classier in two GMM-UBM based text-independent speaker verification systems to improve the performance. In the first system, both hypothesized speaker and ...

May 22, 2020

Energy Savings in LTE Macro Base Stations

  • Ambrosy A.
  • Blume O.
  • Ferling D.
  • Jueschke P.
  • Wilhelm M.
  • Yu X.

In wireless access networks the traffic load varies strongly along a day and efficient concepts to adapt the power consumption of LTE macro base stations to the required traffic load are currently widely under study. Significant daily energy savings up to 35% can be achieved for different deployment scenarios by ...

February 19, 2017

Enhancing Mobile Networks with Software Defined Networking and Cloud Computing

  • Cao Z.
  • Kodialam M.
  • Lakshman T.
  • Panwar S.

In the past decade, mobile devices and applications have experienced an explosive growth, and users are expecting higher data rates and better quality services every year. In this paper, we propose several ideas to increase wireless network functionality and capacity using software-defined networking and cloud computing. Connections in mobile networks ...