Long-lasting emission from femtosecond excitation of nitrogen-based flows shows promise as a useful mechanism for molecular tagging velocimetry instrument. The technique, known laser electronic (FLEET), was invented at Princeton decade ago and has quickly been adopted used in variety high-speed ground test flow facilities. short temporal scales offered by amplifiers permit nonresonant multiphot...

The dense molecular cloud cores that form stars, like other self-gravitating objects, undergo bulk oscillations. Just at the point of gravitational instability, their fundamental oscillation mode has zero frequency. We study, using perturbation theory, the evolution of a spherical cloud that possesses such a frozen mode. We find that the cloud undergoes a prolonged epoch of subsonic, accelerati...

Aerodynamics of trucks and other high sided vehicles is of significant interest in reducing road side accidents due to wind loading and in improving fuel economy. Recognizing the limitations of conventional wind tunnel testing, considerable efforts have been invested in the last decade to study vehicle aerodynamics computationally. In this paper, a three-dimensional near field flow analysis has...