Weak Dissipative solutions to a free-boundary problem for finitely extensible bead-spring chain molecules: variable viscosity coefficients

TL;DR

This paper proves the global existence of weak solutions for a free boundary problem modeling dilute polymers with variable viscosity, extending previous models by considering density-dependent viscosity coefficients and analyzing the limit as the adiabatic exponent approaches infinity.

Contribution

It introduces a new approach to construct weak solutions for a free boundary problem with variable viscosity coefficients depending on polymer density, extending prior work on similar models.

Findings

Established the existence of weak solutions for the free boundary problem.

Proved the weak sequential stability of the solution family.

Extended the model to include density-dependent viscosity coefficients.

Abstract

We investigate the global existence of weak solutions to a free boundary problem governing the evolution of finitely extensible bead-spring chains in dilute polymers. The free boundary in the present context is defined with regard to a density threshold of \r{ho} = 1, below which the fluid is modeled as compressible and above which the fluid is modeled as incompressible. The present article focuses on the physically relevant case in which the viscosity coefficients present in the system depend on the polymer number density, extending the earlier work [8]. We construct the weak solutions of the free boundary problem by perform ing the asymptotic limit as the adiabatic exponent \gamma goes to \infty for the macroscopic model introduced by Feireisl, Lu and Suli in [10] (see also [6]). The weak sequential stability of the family of dissipative (finite energy) weak solutions to the free boundary problem is also established.