In this paper, we consider the unsteady flow of a micropolar fluid through a thin pipe with the nonzero boundary condition for microrotation. We first prove the well-posedness of the corresponding initial-boundary value problem governing the flow. Then, using asymptotic analysis with respect to the pipe’s thickness, we construct the higher-order approximation of the solution. The proposed
... [Show full abstract] approximation is given in explicit form, taking into account the effects of the boundary conditions, the micropolar nature of the fluid as well as the time derivative. A detailed study of the boundary layers in the vicinity of the pipe’s ends is also provided along with a numerical example illustrating the behaviour of the derived asymptotic solution.