Hokkaido University Preprint Series in Mathematics
This paper studies the analyticity of the Stokes semigroup in an infinite cylinder or more generally a cylindrical domain with several exits to infinity in the space C0; , the L 1 -closure of all smooth compactly supported solenoidal vector fields. These domains are not strictly admissible in the sense of the first two authors (2014). However, it is shown that these domains are still admissible which yields the analyticity in C0; . A new proof based on a blow-up argument is given to derive an L 1 -type resolvent estimate which enables us to conclude that the analyticity angle of the Stokes semigroup in C0; is =2.