  We consider a new way of establishing Navier wall laws. Considering a bounded
domain $\Omega$ of R N , N=2,3, surrounded by a thin layer $\Sigma \epsilon$,
along a part $\Gamma$2 of its boundary $\partial \Omega$, we consider a
Navier-Stokes flow in $\Omega \cup \partial \Omega \cup \Sigma \epsilon$ with
Reynolds' number of order 1/$\epsilon$ in $\Sigma \epsilon$. Using
$\Gamma$-convergence arguments, we describe the asymptotic behaviour of the
solution of this problem and get a general Navier law involving a matrix of
Borel measures having the same support contained in the interface $\Gamma$2. We
then consider two special cases where we characterize this matrix of measures.
As a further application, we consider an optimal control problem within this
context.
