Global existence and long time behavior of solutions to some Oldroyd type models in hybrid Besov spaces

In this paper, we deal with some Oldroyd type models, which describe incompressible viscoelastic fluids. There are 3 parameters in these models: the viscous coefficient of fluid ν₁, the viscous coefficient of the elastic part of the stress tensor ν₂, and the damping coefficient of the elastic part of the stress tensor α. In this paper, we assume at least one of the parameters is zero: (ν₁, ν₂,α)=(+,0,+), (+,0,0), (0,+,+), (0,+,0), (0,0,+) and prove the global existence of unique solutions to all these 5 cases in the framework of hybrid Besov spaces. We also derive decay rates of the solutions except for the case (ν₁, ν₂,α)=(+,0,0). To the best of our knowledge, decay rates in this paper are the first results in this framework, and can improve some previous works.