This DNS study is focused on the structure of turbulence in a boundary layer. First, it is not appropriate to call the turbulent flow as a “random” motion. Any mean flow like Blasius solution, which is a Navier-Stokes solution, added by white noise or random perturbation would be rejected by Navier-Stokes equations and the perturbation will be damped quickly. The governing Navier-Stokes equatio...

The performance of the electric submersible pump (ESP) significantly affected by Gas Void Fraction (GVF). Thus, using of a Rotary Gas Separator (RGS) is a suitable solution for this issue. The performance of the RGS is function of different parameters such as geometry of impeller, rotating speed, boundary conditions, media viscosity and GVF. In this study, the influences of GVF, viscosity, and ...

In many industrial equipment such as boilers and heat exchangers, the cylindrical tubes are exposed to the gas- liquid two phase flow. For any immersed body in flow field vortex shedding is created with a frequency that may be constant or variable, according to conditions such as flow rates, geometry of body, and etc. The failure will happen in the equipment, when this frequency is close to...

This article reviews some recent simulations of vortex sheet roll-up using the vortex blob method. In planar and axisymmetric flow, the roll-up is initially smooth but irregular small-scale features develop later in time due to the onset of chaos. A numerically generated Poincaré section shows that the vortex sheet flow resembles a chaotic Hamiltonian system with resonance bands and a heterocli...

The stability of supercritical Couette flow has been studied extensively, but few measurements of the velocity field of flow have been made. Particle image velocimetry (PIV) was used to measure the axial and radial velocities in a meridional plane for non-wavy and wavy Taylor–Couette flow in the annulus between a rotating inner cylinder and a fixed outer cylinder with fixed end conditions. The ...

Electron columns confined magnetically in vacuum evolve in ðr; hÞ as N 10 field-aligned rods of charge, or point vortices. Neglecting discreteness, the column evolves as would vorticity in an inviscid, incompressible fluid, governed by the Euler equations. The macroscopic flow dynamics is readily imaged, including effects such as surface waves and inviscid damping, two vortex merger, and gradie...

In this article, a Ranque–Hilsch Vortex Tube has been optimized utilizing axial angles for nozzles. Effect of nozzles angles on the flow behavior has been investigated by computational fluid dynamics (CFD) techniques. A finite volume approach with the standard k–ε turbulence model has been used to carry out all the computations. The dimensions of studied vortex tubes are kept the same for all m...

Crossflow-vortex-induced laminar breakdown in a three-dimensional flat-plate boundary-layer flow is investigated in detail by means of spatial direct numerical simulations. The base flow is generic for an infinite swept wing, with decreasing favourable chordwise pressure gradient. First, the downstream growth and nonlinear saturation states initiated by a crossflow-vortex-mode packet as well as...

The vortex stretching process is relevant to energy transport at various scales in turbulent flow and in vortex reconnection. For these, reasons, exact solutions for vortex flow are useful. Robinson and Saffman [1] examined the Burgers vortex solution and found closed form steady solutions for special parameter values. Unsteady 2D Burgers vortex solutions have been used to model the spanwise st...