Unsteady flow models of wings and airfoils have been studied to understand the aerodynamic performance of natural flyers and provide improved maneuverability for micro aerial vehicles (MAVs). Vortex methods have been extensively applied to reduce the dimensionality of these aerodynamic models, based on the proper estimation of the distribution and evolution of the vortices in the wake. In such ...

We apply the phase-reduction analysis to examine synchronization properties of periodic fluid flows. The dynamics of unsteady flows are described in terms of the phase dynamics reducing the high-dimensional fluid flow to its single scalar phase variable. We characterize the phase response to impulse perturbations, which can in turn quantify the influence of periodic perturbations on the unstead...

The paper presents an adjoint based approach for determining global error in the time domain that is relevant to scalar outputs computed as functions of the unsteady flow solution. The algorithm is derived for the unsteady Euler equations and takes into account the effect of dynamic meshes. Two primary components of the total error are specifically identified, namely, the error due to temporal ...

This paper presents an Euler and boundary-layer method capable of unsteady flow and aeroelastic simulations. An integral boundary-layer solver is coupled with an Euler solver in a “semi-inverse” manner. For the inviscid part, approximate wall boundaryconditions are implemented on non-moving mean chord positions, whereas the full nonlinear Euler equation is solved in the field for accurate resol...

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...

Flood waves resulting from dam breaks and flash floods have been responsible for numerous losses. In the present study, sudden flood releases were investigated down a large stepped waterway initially dry. A new experimental technique was developed to obtain instantaneous void fractions, bubble count rates and velocities. Unsteady air-water flow properties were recorded with arrays of conductivi...