In this paper, formation and development of one of the most dominant VORTEX structures, namely, counterrotating VORTEX pair (CVP) which is seen in the jet in cross flow are investigated numerically. Influences of the inclination angles between the nozzle (s) and channel on the CVP are presented for three inclination angles, a=30o, 60o and 90o at velocity ratio, R=2.0. Effects of the number of the nozzles on the evolution of CVP is analyzed by considering the single and three side-by-side positioned circular nozzles. In addition to the CVP, some secondary vortices are also reported by considered relatively a narrow channel because their existence cannot be showed in wider channel. Simulations reveal that higher the inclination angle the more jet penetration into the channel in all directions and increasing the inclination angle causes larger CVPs in size.Although the flow structure of the CVP formed in the single and three side-by-side nozzles are similar their evolution is quite different.

Formation of singular vortices in a magnetized plasma is presented. One is "plasma hole", which is characterized by fast azimuthal rotation and a density hole in its core region. It is found that the charge neutrality condition does break down in the hole region over 1000 times the Debye length. Another example is an anti-E×B VORTEX, which rotates in the opposite direction to the E×B drift. This result means that there exists a predominant force acting on ions other than the electric field. The interaction between ions and neutral flow and the resultant momentum transfer play an essential role on generation of anti-E x B rotation.

In this study, flow behind rectangular vane type VORTEX generators mounted on a flat plate, is numerically simulated using the immersed boundary (IB) method. In the present work, the direct forcing IB method is employed because of its simplicity and high efficiency. VORTEX generators of two different heights are numerically investigated. The height of vanes in the first case is close to the definition of submerged/lowprofile VORTEX generators while the other case is closer to the definition of a conventional VORTEX generator. The resultant highly three-dimensional flow and its transition to turbulence have been studied. Counterrotating vortices generated by these passive rectangular VORTEX generators are characterized. Streamwise evolution of non-dimensionalised maximum values of vorticity, VORTEX strength, streamwise velocity and wall-normal velocity are studied. The simulations show that the IB method in conjunction with DNS effectively simulates the time-dependent flow behind an array of passive VORTEX generators placed in an initially laminar boundary layer.

Microvalves can play an essential role in transport and control of fluids for biomedical applications. These valves may face reliability issues as they can fail due to deterioration of the moving parts exposed to prolonged and repeated movements or handling fluids that contain particles of several microns in diameter. An alternative to valves with moving parts are microdiodes such as micro VORTEX diode, which offers high resistance to flow in one direction and much smaller resistance in the opposite direction. The present study is focused on developing a two-step computationally-based approach for design and optimization of micro VORTEX diodes. A numerical design optimization based on the Design of Experiment and Response Surface Method is employed to improve the efficiency of a micro VORTEX diode using geometrical parameters. The results of the optimization study suggest an optimal design with about 69% improvement in efficiency compared to the reference design.

The unstable flow with rotating-stall-like (RS) effects in a rotor-cascade of an axial compressor was numerically investigated. The RS was captured with the reduction in mass flow rate and increasing of exit static pressure with respect to design operating condition of the single rotor. The oscillatory velocity traces during the stall propagation showed that the RS vortices repeat periodically, and the mass flow rate was highly affected by the blockage areas made by stall vortices. The results also showed that large scale vortices highly affects on the generation and growth of the new vortices. An unsteady two-dimensional finite-volume solver was employed for the numerical study which was developed based on Van Leer’s flux splitting algorithm in conjunction with TVD limiters and the κ-ε turbulence model was also employed. The good agreement of the computed mass flow rate with the experimental results validates the numerical study.

Wall shear rate and its axial and azimuthal components were evaluated in stable Taylor vortices. The measurements were carried out in a broad interval of Taylor numbers (52-725) and several gap width (R1/R2=0.5 - 0.8) by two three-segment electro diffusion probes and three single probes flush mounted in the wall of the outer fixed cylinder.The axial distribution of wall shear rate components was obtained by sweeping the vortices along the probes using a slow axial flow. The experimental results were verified by CFD simulations. The knowledge of local wall shear rates and its fluctuations is of primordial interest for industrial applications like tangential filtration, membrane reactors and bioreactors containing shear sensitive cells.

To discover the nonlinear characteristics of pipe flow, we simulated the flow as a sum of many VORTEX rings. As a first step, we investigated the nonlinear interaction among a maximum of three VORTEX rings. The pipe wall was replaced by many bound vortices. A free VORTEX ring moves right or left according to the radius, and that of a particular radius keeps the initial position. The energy of a free VORTEX ring, except when it is close to a wall, coincides with that without boundaries. Two VORTEX rings of equal radii always show a repeated overtaking process. In the case of three VORTEX rings, they show a wide variety of behavior. For certain combinations of radii and the axial spaces among them, the motion, which seems to be very complex, is limited on a curved surface in three-dimensional space whose axes correspond to the three radii. It was found that this simplicity comes from the momentum conservation law, and also that its direction depends on the energy contribution calculated from free VORTEX rings. Our results elucidate the nonlinear behavior among many vortices.