The present paper describes how to apply the Chebyshev orthogonal collocation technique to solve steady-state and unsteady-steady two-dimensional problems. All problems are solved using one single computer algebra, Mathematica . The problems include: (1) steady-state heat transfer in a rectangular bar, (2) steady-state flow in a rectangular duct, (2) steady-state heat transfer in a cooling cyli...

The aerodynamic plasma actuators have shown to be efficient flow control devices in various applications. In this study the results of flow control experiments utilizing single dielectric barrier discharge plasma actuators to control flow separation and unsteady vortex shedding from a circular cylinder in cross-flow are reported. This work is motivated by the need to reduce landing gear noise f...

This paper presents experiments with a new algorithm for the unseady (tranient) thrust control bladed-propeller marine thrusters. Comparative experiments over a wide range of unsteady operating conditions with three different thrust control algorithms demonstrate the model-based control algorithm to offer transient thrust-control performance superior to that of its non-model-based counterpart. ...

Visualization experiments of the unsteady immiscible displacement of a fluid by another are performed on glass-etched pore networks of well-controlled morphology by varying the fluid system and flow conditions. The measured transient responses of the fluid saturation and pressure drop across the porous medium are introduced into numerical solvers of the macroscopic two-phase flow equations to e...

Flow separation limits the efficiency of low-pressure turbines (LPTs) in aircraft engines. Experiments with vortex generator jets (VGJs), conducted in AFRL's low-speed cascade at Wright-Patterson AFB, have demonstrated dramatic reductions in separation losses. The critical science that will enable this design innovation to reach its potential is a comprehensive understanding of the effect of VG...

In this study exemplary results on the influence of two fundamental unsteady parameters, the reduced frequency k and the non-dimensional pitching rate α+, on the transition from a steady to an unsteady flow field around the reference airfoil BAC3-11/RES/30/21 are presented using experimental and numerical techniques. The tools used are described and their results verified with each other. On th...

A study is currently underway to better understand and influence the maneuvering characteristics of autonomous underwater vehicles (AUVs). A two-pronged approach, using traditional quasi-steady state-space modeling as well as maneuvering experiments performed in unsteady Reynolds-averaged Navier-Stokes simulations (URANS), has been adopted to provide the greatest possible insight into vehicle m...

Most theoretical models of unsteady aquatic movement in organisms assume that including steady-state drag force and added mass approximates the hydrodynamic force exerted on an organism's body. However, animals often perform explosively quick movements where high accelerations are realized in a few milliseconds and are followed closely by rapid decelerations. For such highly unsteady movements,...