Nonlinear quasigeostrophic flows in two layers over a topographic slope are considered. Scaling the lower layer potential vorticity equation yields two parameters which indicate the degree of nonlinearity in the lower layer. The first, u' (the strength of the deep flow divided by the product of the effective bottom slope and the squared length scale), is related to the advection of relative vor...

This article reports nonlinear bifurcations observed in a laboratory scale, turbulent combustor operating under imperfectly premixed mode with global equivalence ratio as the control parameter. The results indicate that the dynamics of thermoacoustic instability correspond to quasi-periodic bifurcation to low-dimensional, deterministic chaos, a route that is common to a variety of dissipative n...

The environmental benefits of low emissions lean burn technology in reducing NOx emissions up to 80only be effective when these are deployed to a large range of new aero-engine applications. While integrating methodologies for advanced engine architectures and thermodynamic cycles. It will support European engine manufacturers to pick up and keep pace with the US competitors, being already able...

The dynamics of major flow structures were studied in a gas turbine model combustor for perfectly premixed swirlstabilized flames under a variety of reacting and non-reacting conditions using high-repetition-rate laser diagnostics. The studied combustor is a target case for the International Workshop on Advanced Measurement Techniques and Computational Methods for Premixed and Partially Premixe...

The use of hydrocarbons is very appealing for the realization of high energy density power sources, so long as the fuel can be stored in the liquid phase. As a result, except for the most volatile hydrocarbons, a miniaturized combustor must rely on a good design of the fuel atomizer, which should yield small, rapidly evaporating droplets to generate the fuel vapor promptly, mix it with the oxid...

Photons can carry angular momentum, not only due to their spin, but also due to their spatial structure. This extra twist has been used, for example, to drive circular motion of microscopic particles in optical tweezers as well as to create vortices in quantum gases. Here we excite an atomic transition with a vortex laser beam and demonstrate the transfer of optical orbital angular momentum to ...

In this paper we consider analytically and numerically the dynamics of waves in twodimensional, magnetically trapped Bose-Einstein condensates in the weak interaction limit. In particular, we consider the existence and stability of azimuthally modulated structures such as rings, multi-poles, soliton necklaces, and vortex necklaces. We show how such structures can be constructed from the linear ...

This paper addresses the drag force and formation of vortices in the boundary layer of a Bose-Einstein condensate stirred by a laser beam following the experiments of Phys. Rev. Lett. 83, 2502 (1999)]. We make our analysis in the frame moving at constant speed where the beam is fixed. We find that there is always a drag around the laser beam. We also analyze the mechanism of vortex nucleation. ...