  We study the asymptotic behavior of an incompressible fluid around a bounded
obstacle. The problem is modeled by the stationary Navier-Stokes equations in
an exterior domain in $\R^n$ with $n\ge 2$. We will show that, under some
assumptions, any nontrivial velocity field obeys a minimal decaying rate
$\exp(-Ct^2\log t)$ at infinity. Our proof is based on appropriate Carleman
estimates.
