The experiment uses wind-tunnel modelling method to investigate an intermittent ventilation of pollutants within an urban intersection. The model is designed after a typical inner-city area occurring frequently in European countries. It consists of apartment houses with roofs arranged to the several blocks. Blocks form regular patterns divided by intersections with height to width ratio equal t...

Large-eddy simulations of pairs of artificially generated longitudinal vortices embedded in a two-dimensional turbulent boundary layer are performed to study the dynamics of the vortical structures and to provide the unsteady inflow data for use in a future turbomachinery simulation. An immersed boundarymethod is employed to represent the wall-mounted half-delta wings that generate the counter-...

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...

This study was conducted to examine the effect on airflow of shape an urban road green belt in asymmetrical street canyon. In this paper, field at pedestrian height with different building ratios (ASF) both sides is modeled and simulated using computational fluid dynamics (CFD) software, ANSYS FLUENT, flow rate characteristic distribution index average intensity are used evaluate analyze level....

Flow past deep wall cavities exhibits strong interaction with the standing wave system in the cavity. The shear layer separating the exterior flow from the cavi ty flow supports i nstabil iti es which excite the normal cavity modes. In turn, the cavity wave system reirlforces the instabil i ­ ties. Experimental studies have shown that two distinct instability modes are encountered as the extern...

Topological techniques are used to study the motions of systems of point vortices in the infinite plane, in singly-periodic arrays, and in doubly-periodic lattices. The reduction of each system using its symmetries is described in detail. Restricting to three vortices with zero net circulation, each reduced system is described by a one degree of freedom Hamiltonian. The phase portrait of this r...

One of the solutions of the Helmholtz equation is the vortex beams. In the recent decades, production and applications of these types of beams have found serious attentions. Determination of the vortex beam topological charge and its sign are very important issues. Odd number of reflections of the vortex beam changes its vorticity. In this paper, we have used a q-plate to generate a vortex beam...

the concepts of democracy have been around for centuries in different fields of human sciences. however, in most of these fields the idealistic and far-fetched features attributed to democracy have not been manipulated yet. it should be mentioned that there have been only a few serious attempts to find proper go-between elements, which could make such a concept as comprehensible and tangible as...

We present an experimental investigation of the flow structure and vorticity field in the wake of a NACA-0012 airfoil pitching sinusoidally at small amplitude and high reduced frequencies. Molecular tagging velocimetry is used to quantify the characteristics of the vortex array (circulation, peak vorticity, core size, spatial arrangement) and its downstream evolution over the first chord length...

The unsteady hydrodynamics of two pitching foils arranged in a side-by-side (parallel) configuration is examined for range Strouhal numbers, phase differences, oscillation amplitudes and separation distances. Three distinct vortex patterns are identified the wake maps, which include separated wake, merged transitional-merged wake. Furthermore, novel model introduced based on fundamental flow va...