We present a simple, two dimensional example of a ”cat” – a body with zero angular momentum that can rotate itself with no external forces. This model is used to explain why this problem is known to be a gauge theory and to illustrate the importance of non-commutative operators. We will also show a comparison between the free-space ”cat” in Newtonian mechanics and the same problem in Aristoteli...

The paper presents a low-order prediction scheme for the noise change in multistream jets when the nozzle geometry is altered from a known baseline. The essence of the model is to predict the changes in acoustics due to the redistribution of the mean flow as computed by a Reynolds-Averaged Navier Stokes (RANS) solver. A RANS-based acoustic analogy framework is developed that addresses the noise...

An experimental investigation was conducted to study the average and the fully-developed heat (mass) transfer coefficients in a rectangular smooth duct and a duct with repeated-baffle blockages. The focus of attention in this work is the conventional correlation Nu / Nufd 1 + C / ( X / D ) for the average heat transfer coefficient. It was shown that for relatively short ducts, the coefficient C...

This paper describes several methods for the prediction of jet noise. All but one of the noise prediction schemes are based on Lighthill's or Lilley's acoustic analogy while the other is the jet noise generation model recently proposed by Tam and Auriault.1 In all the approaches some assumptions must be made concerning the statistical properties of the turbulent sources. In each case the charac...

The Reynolds number Re is used as a metric to assess whether or not a flow may contain turbulence. In a weakly ionised gas with an external electric field imposed, ions exert a drag on the neutral particles. Thus, a component of the neutral motion is attributable to the ion-drag. An analogy to Re has been proposed in which the ion-drag-induced velocity contribution to the neutral motion is used...

Simultaneous velocity field and optical distortions along the wall-normal direction were performed in a subsonic boundary layer. Comparison between wavefronts and the ones predicted using instantaneous Strong Reynolds Analogy had shown that instantaneous SRA is valid most of the time. Conditional velocity analysis had shown that positive OPD distortions are created by predominantly ejection-typ...

We investigate the emergent dynamical behavior of hydrodynamically coupled microrotors by means of multiparticle collision dynamics (MPC) simulations. The two rotors are confined in a plane and move along circles driven by active forces. Comparing simulations to theoretical results based on linearized hydrodynamics, we demonstrate that time-dependent hydrodynamic interactions lead to synchroniz...

An experimental investigation is conducted to determine the effect of repeated-plate blockages of variable streamwise spacing on heat transfer characteristics of turbulent flow in rectangular ducts. The plates are attached to the upper and lower walls in a staggered arrangement. The experiments are carried out by mass transfer and the analogy between heat and mass transfer provides the necessar...