State-space representation of the unsteady aerodynamics of flapping flight" (2014). ARTICLE INFO ABSTRACT Article history: A state-space formulation for the aerodynamics of flapping flight is presented. The Duhamel's principle, applied in linear unsteady flows, is extended to non-conventional lift curves to capture the LEV contribution. The aspect ratio effects on the empirical formulae used to...

This research describes aerodynamic characteristics of small-scale wind turbine blade, called Archimedes spiral wind turbine blade. Numerical approaches on the prediction of aerodynamic performance of the blade have been conducted. Both steady and unsteady state numerical simulations using ANSYS CFX are performed on the several cases of rotating speeds. Large scale tip vortex is captured and gr...

A simplified model was employed to develop mathematically equations that describe the unsteadystate behavior of naturally fractured reservoirs, The analysis resulted in an equation of flow of radial symmetry whose solution, for the infinite case, is identical in form and function to that describing the unsteady-state behavior of homogeneous reservoirs. Accepting the assumed model, for all pract...

The unsteady-state aerodynamic performance results of various MEMS-fabricated titanium-alloy wing designs are presented. These wing are tested in a high-quality low-speed wind tunnel with velocity uniformity of 0.5%.. For the first time, we have identified the importance of spanwise stiffness effect in generating the leading edge vortices. These vortices, generated around each wing, cause a low...

We analyze the dynamics of a spatially extended system with bistability between a homogeneous stationary state and an unstable fixed point surrounded by an oscillatory state. We show that a wave front extinguishes homogeneous oscillations, replacing them with unsteady oscillations. A traveling wave solution connects the unsteady oscillations to the stationary state. The difference in potentials...

In this study, direct laboratory measurements of unsteady-state imbibition test are used in a new approach to obtain relative permeability curves with no predetermined functionality assumptions. Four equations of continuity, Darcy’s law, cumulative oil production, and water fractional flow are employed in combination together under certain assumptions to present the new approach which interpret...

A significant improvement to the development of CFD-based unsteady aerodynamic reduced-order models (ROMs) is presented. This improvement involves the simultaneous excitation of the structural modes of the CFD-based unsteady aerodynamic system that enables the computation of the unsteady aerodynamic state-space model using a single CFD execution, independent of the number of structural modes. F...