This paper addresses the question, do the rotational forces in the hovering fruit fly Drosophila melanogaster reflect something different (the Magnus effect) or more of the same (circulatory-and-attached-vortex force)? The results of an unsteady blade-element model using empirically derived force coefficients from translating (root-oscillating) wings are compared with recent results derived fro...

Unsteady inviscid flow models of wings and airfoils have been developed to study the aerodynamics of natural and man-made flyers. Vortex methods have been extensively applied to reduce the dimensionality of these aerodynamic models, based on the proper estimation of the strength and distribution of the vortices in the wake. In such modelling approaches, one of the most fundamental questions is ...

This paper analyses the unsteady, two-dimensional stagnation point flow of an incompressible viscous fluid over a flat sheet when the flow is started impulsively from rest and at the same time, the sheet is suddenly stretched in its own plane with a velocity proportional to the distance from the stagnation point. The partial differential equations governing the laminar boundary layer forced con...

flood routing has many applications in engineering projects and helps designers in understanding the flood flow characteristics in river flows. floods are taken unsteady flows that vary by time and location. equations governing unsteady flows in waterways are continuity and momentum equations which in case of one-dimensional flow the saint-venant hypothesis is considered. dynamic wave model as ...

A harmonic balance technique for modeling unsteady nonlinear  ows in turbomachinery is presented. The analysis exploits the fact that many unsteady  ows of interest in turbomachinery are periodic in time. Thus, the unsteady  ow conservation variables may be represented by a Fourier series in time with spatially varying coefŽ cients. This assumption leads to a harmonic balance form of the Eul...

A bridge is built between projection methods and SIMPLE type methods (Semi-Implicit Method for Pressure-Linked Equation). A general second-order accurate projection method is developed for the simulation of incompressible unsteady flows by employing a non-linear update of pressure term as n∇ pn+1 + (I − n)∇ pn , where n is a coefficient matrix, which may depend on the grid size, time step and e...

As a fundamental study in the application to direct-injection spark-ignition engines or gas turbines, in which mixture stratification and partial quenching are of serious concerns, unsteady premixed methane/ air flames subjected to time-varying composition fluctuations are investigated computationally. The code OPUS employs an unsteady opposed-flow combustion configuration, including detailed c...

Preconditioning methods have become the method of choice for the solution of flowfields involving the simultaneous presence of low Mach number flow and transonic flow regions. It is well known that these methods are important for insuring accurate numerical discretization as well as convergence efficiency over various operating conditions such as low Mach number, low Reynolds number and high St...

Buffeting is an aeroelastic phenomenon which plagues high performance aircraft at high angles of attack. For the F/A-18 at high angles of attack, vortices emanating from wing/fuselage leading edge extensions burst, immersing the vertical tails in their turbulent wake. The resulting buffeting of the vertical tails is a concern from fatigue and inspection points of view. Previous flight and wind-...

BACKGROUND AND PURPOSE We investigated dynamic interfoot distance (IFD) throughout the gait cycle in people with unsteady gait caused by vestibulopathy and in people without known neuromuscular pathology. We expected that the subjects with unsteady gait would use a greater IFD than subjects without neuromuscular pathology and that this IFD would be correlated with other measures of locomotor st...