Recent experiments on particle diffusion in bacterial baths indicate the formation of correlated structures in the form of bacterial swirls. Here we predict that such a structural ordering would give rise to the new effect of propagating shear waves in a bacterial bath at length scales of the order of a swirl, which corresponds to time scales of the order of the lifetime of a swirl. Our predict...

Observations of tornadoes in the field and laboratory investigations of tornado-like end-wall vortices have both demonstrated the complexity of this fluid phenomenon. The structure of the core region in particular depends on a number of parameters, one being the swirl ratio (S), i.e the degree of swirl in the background flow (DaviesJones, 1976), another being the degree of roughness of the unde...

Ammonia has been proposed as a potential energy storage medium in the transition towards a lowcarbon economy. This paper details experimental results and numerical calculations obtained to progress towards optimisation of fuel injection and fluidic stabilisation in swirl burners with ammonia as the primary fuel. A generic tangential swirl burner has been employed to determine flame stability an...

This paper reviews the efforts to construct (or prove the impossibility of) singular solutions of the Euler equations for three dimensional incompressible flow. A semi-analytic approach to this problem is formulated based on numerical computation of complex traveling wave solutions, followed by perturbation construction of a real solution, for axisymmetric flow with swirl. The perturbation anal...

Rayleigh scattering temperature measurements were obtained in a turbulent reactive swirling coaxial jet discharged from a swirl-stabilized burner along the jet-flame centerline. They are reported up to 10 fuel nozzle diameters downstream of the burner exit at a Reynolds number of 29000. The effect of swirl numbers (S=0.3, 0.58, 1.07) on the temperature fields, the power spectral density of temp...

A predictive model for droplet size and velocity distributions of a pressure swirl atomizer has been proposed based on the maximum entropy formalism (MEF). The constraint conditions of the MEF model include the conservation laws of mass, momentum, and energy. The effects of liquid swirling strength, Weber number, gas-to-liquid axial velocity ratio and gas-to-liquid density ratio on the droplet ...

ABSTRACT An axisymmetric, turbulent, multigrid computational fluid dynamics (CFD) code is used, on a parallel computing facility, to predict the mixing between superposed flows in a pre−swirl rotor−stator system, being a simplified representation of the internal air cooling system in gas turbine engines. Strong recirculations formed by the pre−swirl cross−flow lead to entrainment of disc−coolin...

Human-generated lists are a form of non-iid data with important applications in machine learning and cognitive psychology. We propose a generative model — sampling with reduced replacement (SWIRL) — for such lists. We discuss SWIRL’s relation to standard sampling paradigms, provide the maximum likelihood estimate for learning, and demonstrate its value with two real-world applications: (i) In a...

Since a large number of physical variables are involved in the combustion process occurring in complex swirl stabilized combustors, simple systems (burner stabilized laminar flat flames) were initially studied (see chapters 5 and 6). Having understood the dynamics of laminar flat flames and developed methodologies to build reduced order flame dynamic models, the technique developed to measure t...

An experimental and numerical investigation on the effect of swirl on the motion of coal particles in the near-burner region of a versatile multi-fuel swirl-stabilised laboratory burner of total thermal input of 100kW, has been performed. The burner was designed as a scale model of a lOMW coal burner operating in a cement rotary kiln, produces flames of different aerodynamic characteristics, an...