Holder continuity of Keller-Segel equations of porous medium type coupled to fluid equations

Abstract: We consider a coupled system consisting of a degenerate porous medium type of Keller-Segel system and Stokes system modeling the motion of swimming bacteria living in fluid and consuming oxygen. We establish the global existence of weak solutions and H\"older continuous solutions in dimension three, under the assumption that the power of degeneracy is above a certain number depending on given parameter values. To show H\"older continuity of weak solutions, we consider a single degenerate porous medium equation with lower order terms, and via a unified method of proof, we obtain H\"older regularity, which is of independent interest.