Abstract. We prove global well-posedness for the microscopic FENE model under a sharp boundary requirement. The well-posedness of the FENE model that consists of the incompressible Navier-Stokes equation and the Fokker-Planck equation has been studied intensively, mostly with the zero flux boundary condition. Recently it was illustrated by C. Liu and H. Liu [2008, SIAM J. Appl. Math., 68(5):1304-1315] that any preassigned boundary value of a weighted distribution will become redundant once the non-dimensional parameter b > 2. In this article, we show that for the well-posedness of the microscopic FENE model (b > 2) the least boundary requirement is that the distribution near boundary needs to approach zero faster than the distance function. Under this condition, it is shown that there exists a unique weak solution in a weighted Sobolev space. Moreover, such a condition still ensures that the distribution is a probability density. The sharpness of this boundary requirement is shown by a construction of infinitely many solutions when the distribution approaches zero as fast as the distance function.
Moreover, this condition is equivalent to the zero flux boundary condition for b > 2 as shown in REF ,
Global Well-Posedness for the Microscopic FENE Model with a Sharp Boundary Condition
arXiv: Analysis of PDEs
Mathematics