We introduce an adaptative coupling of the Boltzmann and Navier-Stokes
equations to compute hypersonic flows around a vehicle at high altitu
de. The coupling is achieved by matching half fluxes at the interface
of the Boltzmann and Navier-Stokes domains. The domains are determined
automatically by computing local kinetic residuals on a preliminary N
avier-Stokes solution. Our method is developed here for monoatomic gas
es. Different numerical results illustrate its validity and limits. (C
) 1997 Academic Press.