BACKGROUND The shoulder is the most complex joint in the body. The large freedom of motion in this joint is the main cause of instability. Instability varies in its degree, direction, etiology and volition and there is a large spectrum of conditions. METHODS Based on literature research and also in our own experience, we propose to elucidate the reader about the natural history of instability...

In this paper, 3-dimensional linear instability analysis has been carried out for unsteady pipe flow. An inflectional velocity profile from [2] has been considered and the stability analysis of it has been carried out for (axisymmetric mode) and 0 = n 2 & 1 = n . It was revealed that the profile is unstable for both axisymmetric and non-axisymmetric modes. The mode 1 = n was observed to be most...

Research involving the interaction of flow with morphological instability during directional solidification of binary alloys is reviewed. In general, flow may arise during the solidification process from thermal and solutal buoyancy, changes in density upon solidification, thermocapillary forces at free boundaries, or external forcing of the system. We focus primarily on the last of these, givi...

The dynamical origin of large-scale flows in systems driven by concentrated Archimedean forces is considered. A two-dimensional model of plumes, such as those observed in thermal convection at large Rayleigh and Prandtl numbers, is introduced. From this model, we deduce the onset of mean flow as an instability of a convective state consisting of parallel vertical flow supported by buoyancy forc...

in this work a numerical study of thermal and fluid dynamics behavior of natural air convection in a square cavity in a laminar flow is presented, by finite volume method. the square cavity has two walls heated with different temperatures and two isolated walls. the numerical simulation is made up of several rayleigh numbers to . flow and isotherm lines are presented and analyzed. the numerical...

Two-phase flow instability in microchannel flow boiling exhibits pressure fluctuations with different frequencies and amplitudes. One possible way to suppress the dynamic instability is to introduce synthetic jet near the inlet of the channel. An important feature of synthetic jet is that it allows momentum transfer into the microchannel flow without net mass injection into it. The strength and...

We demonstrate that arbitrarily weak magnetic field may cause violent instability of an anticyclonic, recirculating flow with uniform mean angular velocity. This magnetohydrodynamic instability would trigger turbulence in the cores of vortices where neither centrifugal, exchange instability, nor magnetorotational instability is effective. In the accretion disk vortices this can be an important ...

Trapping of vortices in a cavity has been explored in recent years as a drag reduction measure for thick airfoils. If, however, trapping fails, then oscillation of the cavity flow may couple with elastic vibration modes of the airfoil. To examine this scenario, the effect of small amplitude vertical motion on the oscillation of the shear layer above the cavity is studied by acoustic forcing sim...

Convective instability in an open flow system with distributed time scales from upstream to downstream is studied. By exploiting the convective instability, the upstream fluctuation with fast time scale is not only amplified along the flow but is also slowed down along the flow to the downstream. Through the instability, statistical property of the downstream shows sensitive dependence on the d...