Much of the atmospheric variability in the North Atlantic sector is associated with variations in the eddy-driven component of the zonal flow. Here we present a simple method to specifically diagnose this component of the flow using the low-level wind field (925-700 hPa). We focus on the North Atlantic winter season in the ERA-40 reanalysis. Diagnostics of the latitude and speed of the eddy-dri...

A passive jet flow control method was employed to suppress the unsteady vortex shedding from a circular cylinder at the Reynolds number level of Re= (0.18~1.1)×10. The passive jet flow control was achieved by blowing jets from the holes near the rear stagnation point of the cylinder, which are connected to the in-take holes located near the front stagnation point through channels embedded insid...

In this study, the missile staging process by implementing a side-injected jet is simulated numerically. The problem is considered to be axisymmetric and the thin shear layer approximation of Navier-Stokes equations along with an algebraic turbulence model is used in a quasi-static form for the calculations. The free stream corresponds to a very high altitude flight condition with a Mach number...

Using of nanofluids and ducts with corrugated walls are both supposed to enhance heat transfer, by increasing the heat transfer fluid conductivity and the heat transfer area respectively. Use of a diverging duct with a jet at inlet section may further increase heat transfer by creating recirculation zones inside the duct. In this work two-dimensional incompressible laminar flow of a nanofluid e...

An axisymmetric jet issued from a sharp edged circular convergent nozzle has been studied experimentally in the near field at Reynolds number 5.3x104  to search the saddle shape behavior of mean velocity and the role of mean static pressure in the jet flow. Due to the vena contracta effect the centerline mean velocity of the jet increases about 4.2% of its exit value and corresponding decrease ...

the effect of a combined system of the bed suction and jet injection as a pier-scour countermeasure on the turbulent flow field is studied in a laboratory flume using an acoustic doppler velocimeter (adv). the three components of the velocities in the vertical symmetry plane in the equilibrium scour hole in front and rear of the pier under 3-jet injections and bed suction rate qs/q0 = 2%located...

This paper describes an approach to periodic reference tracking in a pulsed-jet-injection experimental study. The objective was to match the jet’s temporal velocity profile to a periodic reference. The challenge lies in controlling the highly nonlinear and poorly understood dynamics associated with the jet velocity. Although the actuator maintains good authority over the jet velocity, the nonli...

A laser-Doppler velocimeter suitable for the measurement of mean and fluctuating flow velocities in water is described. Results of a study using this system in an axisymmetric turbulent jet of water and dilute polymer solutions are given. The laser-Doppler technique is better suited for such measurements than either Pitot tubes or heat-transfer gauges because the Doppler velocity measurements a...

one of the most concerning issues for researchers is to predict the shape and dimensions of the scour pit nearhydraulic structures such as the base of bridges, weirs, valves and stilling basins due to both financial and humanhazards induced by destruction of the structure. as the scour issue has its own complexity in relation to themultiplicity of effecting factors on it, in this study therefor...