Detailed field measurements and simulations of three-dimensional flow structure were used to develop a conceptual model to explain the sustainability of self-formed pool-riffle sequences in gravel-bed rivers. The analysis was conducted at the Red River Wildlife Management Area in Idaho, USA, and enabled characterization of the flow structure through two consecutive pool-riffle sequences, includ...

Repetitively pulsed, nonequilibrium plasma discharges are studied for their ability to ignite and stabilize methane jet flames in cross flow air. The placement of the discharge is surveyed to optimize the flame duty cycle (stability). We find that flame ignition is not achieved when the discharge is located in the potential core region of the fuel jet or on the windward side of the most upstrea...

The nanoparticle transportation and Brownian diffusion in planar jet flow is simulated via large eddy simulation in this work. To thorough compare the Brownian diffusion with different particle size, we computed three particle diameter dp = 1 nm, 10 nm and 50 nm in one simulation process simultaneously. The numerical results showed that at the flow developing stage, the particle mass concentrat...

A nanosecond pulsed plasma discharge located between two fuel jets is used to ignite and hold jet flames in supersonic crossflows, without the use of additional devices (e.g., cavities or backsteps) for flame holding. The fuel injection nozzles and discharge electrodes are mounted flush with the surface of the flat wall adjacent to the freestream flow. The nonequilibrium plasma is produced by r...

We present an experimental and modelling study of a strong gravity wave event in the upper troposphere/lower stratosphere near the Scandinavian mountain ridge. Continuous VHF radar measurements during the MaCWAVE rocket and ground-based measurement campaign were performed at the Norwegian Andoya Rocket Range (ARR) near Andenes (69.3 N, 16 E) in January 2003. Detailed gravity wave investigations...

Temperature fluctuation in fluid causes high cycle thermal fatigue in shroud structure according to its amplitude and frequency. There are still some incidents of thermal fatigue and leakage in light water reactors (Japanese PWR Tomari-2 in 2003, French PWR CIVAUX in 1998), and also in sodium cooled reactors (French FBR PHENIX in 1992). Mixing tee is a typical component where temperature fluctu...

We adress the question of the stability of a confined coflowing jet at low Reynolds number in various geometries. Our study is motivated by recent experiments in microfluidic devices. When immiscible fluids flow in microchannels, either monodisperse droplets or parallel flows are obtained depending upon the flow rate of the aqueous phase and the oil phase. In these experiments, the confining an...

Near-field acoustical holography methods are used to predict sound radiation from an engine installed on a high-performance military fighter aircraft. Cylindrical holography techniques are an efficient approach to measure the large and complex sound fields produced by full-scale jets. It is shown that a ground-based, one-dimensional array of microphones can be used in conjunction with a cylindr...

The accumulation of well-sampled X-ray, optical, and radio light curves of blazars and coredominated radio galaxies allows analysis of the long-term variability properties and crossfrequency correlations. Armed with this rich database, we are starting to be able to determine where in the jet the nonthermal flares take place. We find that these can occur in at least two locations: in the core se...

The three-dimensional incompressible flow past a rectangular open cavity is investigated, where the aspect ratio of the cavity is considered as 4. The principle objective is to use large-eddy simulation to resolve and control the large-scale structures, which are largely responsible for flow oscillations in a cavity. The flow past an open cavity is very common in aerospace applications and can ...