2025/01/28 by Andrei Gruzinov, Gruzinov, Andrei
Engineering · Mathematics · #Classical mechanics #Computational Fluid Dynamics and Aerodynamics #FOS: Physical sciences #Fluid Dynamics and Turbulent Flows #Gas Dynamics and Kinetic Theory #High Energy Astrophysical Phenomena (astro-ph.HE) #Mechanics #Physics
paper · pdf · doi:10.48550/arxiv.2501.17341
published in arXiv (Cornell University) (Cornell University)
openalex publication_date 2025/01/28 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
Collisionless shocks, essential for astrophysics, perhaps do not exist as statistically stationary solutions. If so, any quantitative statement about a collisionless shock should be qualified by the age of the shock. A theoretical description of the upstream of the 1+1 dimensional electrostatic collisionless shock is developed -- collisionless hydrodynamics. Peculiarities of collisionless hydrodynamics prevent a shock formation when a piston is driven into cold plasma. An exact self-similar solution is found instead; the spatial extent of the solution grows linearly in time. Direct numerical simulations of plasma kinetics in 1+1 dimensions confirm the hydrodynamic result -- a statistically steady collisionless shock doesn't exist. Instead, at each fixed time, there is a continuous succession in space of marginally stable velocity distribution functions. The spatial support of this continuous succession grows linearly in time.