Academy of Mathematics and Systems Science, CAS Colloquia & Seminars
Speaker:
许刚 教授，南京师范大学
Inviter:
王益 研究员
Title:
The global smooth solutions of 3-D compressible Euler equations with vanishing density at infinite time
Time & Venue:
2018.12.13 16:00 N613
Abstract:
In this paper, we are concerned with the global smooth solution problem for 3-D compressible isentropic Euler equations with vanishing density at infinite time. It is well-known that the classical solution of compressible Euler equations generally forms the shock as well as blows up in finite time due to the compression of gases. However, for the rarefactive gases, it is expected that the compressible Euler equations will admit global smooth solutions. We now focus on the movement of compressible gases in an infinitely expanding ball. Because of the conservation of mass, the fluid in the expanding ball becomes rarefied meanwhile there are no appearances of vacuum domains in any part of the expansive ball, which is easily observed in finite time. We will confirm this interesting phenomenon from the mathematical point of view. Through constructing some ingenious anisotropy weighted Sobolev spaces, and by carrying out the new observations and involved analysis on the radial speed and angular speeds together with the divergence and rotations of velocity, the uniform weighted estimates on sound speed and velocity are established. From this, the pointwise time-decay estimate of sound speed is obtained, and the smooth gas fluids without vacuum are shown to exist globally.