11 research outputs found
Scaling of Circulation in Buoyancy Generated Vortices
The temporal evolution of the fluid circulation generated by a buoyancy force
when two-dimensional (2D) arrays of 2D thermals are released into a quiescent
incompressible fluid is studied through the results of numerous lattice
Boltzmann simulations. It is observed that the circulation magnitude grows to a
maximum value in a finite time. When both the maximum circulation and the time
at which it occurs are non-dimensionalised by appropriately defined
characteristic scales, it is shown that two simple Prandtl number (Pr)
dependent scaling relations can be devised that fit these data very well over
nine decades of Pr spanning the viscous and diffusive regimes and six decades
of Rayleigh number (Ra) in the low Ra regime. Also, obtained analytically is
the exact result that circulation magnitude continues to grow in time for a
single buoyant vortex ring in an infinite unbounded fluid.Comment: 4 pages, 3 figures, submitted to Physical Review Letter
The pinch-off process in a starting buoyant plume
The vortex ring formation process of a starting buoyant plume was studied experimentally using digital particle image thermometry and velocimetry (DPITV). The vortex ring was observed to pinch-off, or become disconnected, from the trailing plume. Pinch-off occurred at non-dimensional times, or formation numbers, between 4.4 and 4.9. The observed pinch-off process is consistent with an explanation based upon the Kelvin–Benjamin variational principle. This is analogous to the pinch-off of a vortex ring generated using a piston–cylinder apparatus, suggesting that pinch-off is a general component of the vortex ring formation process for various generation mechanisms
Physiotherapists’ Perspectives on the Threats Facing Their Profession in the Areas of Leadership, Burnout, and Branding: A Pan-Canadian Perspective from the Physio Moves Canada Project, Part 3
Relationships of some socio-personal factors to mathematics achievement of secondary school and university students in Bophuthatswana
With or without ? Hunting for the seed of the matter-antimatter asymmetry
International audienceThe matter-antimatter asymmetry underlines the incompleteness of the current understanding of particle physics. Neutrinoless double-beta () decay may help explain this asymmetry, while unveiling the Majorana nature of the neutrino. The CUORE experiment searches for decay of Te using a tonne-scale cryogenic calorimeter operated at milli-kelvin temperatures. We report no evidence for decay and place a lower limit on the half-life of T 3.8 10 years (90% C.I.) with over 2 tonneyear TeO exposure. The tools and techniques developed for this result and the 5 year stable operation of nearly 1000 detectors demonstrate the infrastructure for a next-generation experiment capable of searching for decay across multiple isotopes
With or without ? Hunting for the seed of the matter-antimatter asymmetry
International audienceThe matter-antimatter asymmetry underlines the incompleteness of the current understanding of particle physics. Neutrinoless double-beta () decay may help explain this asymmetry, while unveiling the Majorana nature of the neutrino. The CUORE experiment searches for decay of Te using a tonne-scale cryogenic calorimeter operated at milli-kelvin temperatures. We report no evidence for decay and place a lower limit on the half-life of T 3.8 10 years (90% C.I.) with over 2 tonneyear TeO exposure. The tools and techniques developed for this result and the 5 year stable operation of nearly 1000 detectors demonstrate the infrastructure for a next-generation experiment capable of searching for decay across multiple isotopes