相关论文: Shock minimized supersonic flight by heating
It is shown that a broad density perturbation in a Fermi (Tonks) cloud takes a shock wave form in the course of time evolution. A very accurate analytical description of shock formation is provided. A simple experimental setup for the…
In the solar atmosphere, jets are prevalent and they are significant for the mass and energy transport. Here we conduct numerical simulations to investigate the mass and energy contributions of the recently observed high-speed jets to the…
Shock waves play an important role in turbulent astrophysical media by compressing the gas and dissipating the turbulent energy into the thermal energy. We here study shocks in magnetohydrodynamic turbulence using high-resolution…
I present an extension of the thin layer approximation to non-axisymmetric bow shocks. By choosing a suitable set of curvilinear coordinates that matches the geometry of a generally distorted bow shock surface, I derive the fluid equations…
Superradiance, the process by which waves are amplified through energy and angular momentum transfer, can also occur in horizonless objects like boson stars, due to both the real space and internal field space rotations. In this work, we…
We consider the shock structures that can arise in blazar jets as a consequence of variations in the jet flow velocity. There are two possible cases: (1) A double shock system consisting of both a forward and reverse shock (2) A single…
Supersonic jet noise reduction is important for high speed military aircraft. Lower acoustic levels would reduce structural fatigue leading to longer lifetime of the jet aircraft. It is not solely structural aspects which are of importance,…
The processes of merging and splitting dilute-gas Bose-Einstein condensates are studied in the nonadiabatic, high-density regime. Rich dynamics are found. Depending on the experimental parameters, uniform soliton trains containing more than…
Pulsars traveling at supersonic speeds are often accompanied by cometary bow shocks seen in Halpha. We report on the first detection of a pulsar bow shock in the far-ultraviolet (FUV). We detected it in FUV images of the nearest millisecond…
Preliminary experiments have been performed to investigate the effects of radiative cooling on plasma jets. Thin (3 um - 5 um) conical shells were irradiated with an intense laser, driving jets with velocities > 100 km/s. Through use of…
We present experimental evidence that a bubble moving in a fluid in which a well-chosen acoustic noise is superimposed can be significantly slowed down for moderate acoustic pressures. Through mean velocity measurements, we show that a…
We present the results of numerical simulations of shock wave-driven jets in the solar atmosphere. The dependence of observable quantities like maximum velocity and deceleration on parameters such as the period and amplitude of initial…
Shock heating by radio jets is potentially an important process in a range of environments, as it will increase the entropy of the heated gas. Although this process is expected to occur in the most powerful radio-loud AGN, strong shocks…
The topic of this review paper is on the influence of solar wind turbulence on shock propagation and its consequence on the acceleration and transport of energetic particles at shocks. As the interplanetary shocks sweep through the…
Underwater sound isolation has been a long-standing fundamental issue in industry and military fields. Starting from a simple theoretical model, here an air-sealed metasurface is proposed to overcome this problem. Comparing with the sample…
The grid of the models of radiative shock waves propagating through partially ionized hydrogen gas with temperature 3000K <= T_1 <= 8000K and density 10^{-12} gm/cm^3 <= \rho_1 <= 10^{-9}gm/cm^3 is computed for shock velocities 20 km/s <=…
Shock wave theory was first studied for gas dynamics, for which shocks appear as compression waves. A shock wave is characterized as a sharp transition, even discontinuity in the flow. In fact, shocks appear in many different physical…
Active galactic nuclei are clearly heating gas in `cooling flows'. The effectiveness and spatial distribution of the heating are controversial. We use three-dimensional simulations on adaptive grids to study the impact on a cooling flow of…
Supersonic outflows from objects as varied as stellar jets, massive stars and novae often exhibit multiple shock waves that overlap one another. When the intersection angle between two shock waves exceeds a critical value, the system…
The velocity relaxation of an impulsively forced spherical particle in a fluid confined by two parallel plane walls is studied using a direct numerical simulation approach. During the relaxation process, the momentum of the particle is…