Time Evolution of the Navier-Stokes Flow in Far-Field

Asymptotic expansion in far-field for the incompressible Navier-Stokes flow are established. It is well known that a velocity decays slowly in far-field. This property prevents classical procedure giving asymptotic expansions of solutions with high-order. In this paper, under natural settings and moment conditions on the initial vorticity, technique of renormalization together with Biot-Savart law derives an asymptotic expansion for velocity with high-order. Especially scalings and large-time behaviors of the expansions are clarified. By employing them, time evolution of velocity in far-field is drawn. As an appendix, asymptotic behavior of solutions as time variable tends to infinity is given. In this assertion, large-time behavior of velocity is discovered clearly.