Direct numerical simulation (DNS) and dynamic mode decomposition (DMD) are used to study the shear layer characteristics of a jet in a crossflow. Experimental observations by Megerian et al. (J. Fluid Mech., vol. 593, 2007, pp. 93–129) at velocity ratios (R = vj/u∞) of 2 and 4 and Reynolds number (Re = vjD/ν) of 2000 on the transition from absolute to convective instability of the upstream shea...

Article history: Received: 09.06.2015. Received in revised form: 01.10.2015. Accepted: 08.10.2015. Liquid nitrogen is expected to be used as a jet medium in petroleum engineering because of its cryogenic and non-polluting characteristics. To identify the velocity distribution characteristics of liquid nitrogen jet, a computational fluid dynamics model was built by coupling the equations for nit...

dissolution pressure and nozzle temperature effects on particle size and distribution were investigated for ress (rapid expansion of supercritical solution) process. supercritical co2 was used as solvent and ibuprofen was applied as the model component in all runs. the resulting ibuprofen nano-particles (about 50 nm in optimized runs) were analyzed by sem and laser diffraction particle size ana...

The unsteady dynamics of planar plumes is investigated numerically with particular emphasis on the pulsating instability characterizing the source ~nozzle! near field. This instability manifests itself as the periodic shedding of vortical structures from the nozzle. The Lagrangian Transport Element Method is used to provide high resolution two-dimensional simulations of the unaveraged variable ...

each year, millions of liters of toxic liquid, are used to combat with pests and plant diseases in farms. the wide spread use of chemical pesticides causes great environmental hazards. particles drift is one of the main problems in spraying which results in the contamination of farm lands, humans and animals. management of particle size is regarded as the main factor in drift control. in this s...

In this research mass transfer coefficient under jetting regime in different directions (from dispersed to continuous and continuous to dispersed phase) has been studied using an experimental setup. n-Butanol-succinic acid-water with low interfacial tension has been selected as experimental chemical system. The effects of various parameters such as jet velocity, nozzle diameter and the heig...

In view of the uneven artificial sowing, low sowing, as well as the fact that the existing seeders cannot meet the sowing requirements of Pteris vittata, this paper designed an automatic plug seeder by using the method of spraying and sowing after mixing spores and water. In order to obtain the optimum working parameters of the seeder, response surface method (RSM) was employed to desi...

An experimental and numerical analysis of a low-angle annular expander nozzle is presented to observe the variance in shock structure within the flow field. A RANS-based axisymmetric numerical model was used to evaluate flow characteristics and the model validated using experimental pressure readings and schlieren images. Results were compared with an equivalent convergingdiverging nozzle to de...

The report describes the results of traverses of the boundary-layer and wake encountered in a small supersonic tunnel at a Mach number of 2.5. The tunnel was arranged with two throats in parallel formed by two shaped walls enclosing a shaped central element. Both the laminar and turbulent boundary-layers were encountered and compared with existing experimental and theoretical results. The frict...

To improve the calculation of the flow properties of an aerospike nozzle, different turbulence models were investigated in this study. The primary shape of the nozzle plug is determined through utilizing an approximate method. The flow field is, then, simulated using the Navier-Stokes equations for compressible flows. The commercial computational fluid dynamics code Fluent is used to simulate t...