We use input-output analysis to examine subsonic and supersonic turbulent jet noise. For a supersonic jet, the leading input-output mode closely resembles wavepackets resulting from the parabolized stability equations (PSE). For a subsonic jet, however, input-output analysis produces several sub-optimal modes with nearly the same gain as the leading input-output mode. The sub-optimal modes depe...

The impact of a potential future fleet of supersonic aircraft on contrail coverage and contrail radiative forcing is investigated by means of simulations with the general circulation model ECHAM4.L39(DLR) including a contrail parameterization. The model simulations consider air traffic inventories of a subsonic fleet and of a combined fleet of suband supersonic aircraft for the years 2025 and 2...

The resurgence in popularity of subsonic .30 caliber bullets in 300 Whisper and 300 Blackout has led to the development of bullets that will expand at subsonic velocities. The availability of these bullets has led to questions about the applicability of this caliber for wildlife damage management. We conducted a preliminary investigation to determine the potential of subsonic .30 caliber bullet...

The long-time behavior of the solution of the system θτ−απτ = Ω(θ), πτ−θτ = πξξ is investigated. Such a system is related to the modeling of detonation waves subjected to strong hydraulic resistance. We establish that some initial conditions yield decay (failure of ignition) while for other initial conditions our results strongly suggest convergence to traveling waves (successful ignition).

ABSTRACT The rate of subsonic wind accretion (accretion on a point Newtonian mass moving through uniform gas) is shown to be independent the velocity and equal spherical Bondi – for adiabatic index 5/3. A (very accurate) numerical calculation flow, confirming this result, also presented.

In this talk, we consider the well-posedness, ill-posedness and the regularity of stationary solutions to the hydrodynamic model of semiconductors represented by Euler-Poisson equations with sonic boundary, and make a classification on these solutions. When the doping profile is subsonic, we prove that, the corresponding steady-state equations with sonic boundary possess a unique interior subso...

This paper studies the liquid to vapor phase transition in a cone shaped nozzle. Using the geometric method presented in [32, 34], we further develop results on subsonic and supersonic evaporation waves in [14] to transonic waves. It is known that transonic waves do not exist if restricted solely to the slow system on the slow manifolds [14]. Thus we consider the existence of transonic waves th...

The hydrodynamic model for semiconductors in one dimension is considered. For perturbated Riemann data, global subsonic (weak) entropy solutions, piecewise continuous and piecewise smooth solutions with shock discontinuities are constructed and their asymptotic behavior is analyzed. In subsonic domains, the solution is smooth and, exponentially as t —> oo, tends to the corresponding stationary ...