I have may be a stupid question - what's the meening of stagnation temperature in free molecular (and also transitional) flow? Can ve calculate it the same way as in continuum flow, i.e. T_stag=T_inf+V_inf^2/(2*Cp)? If yes, than which value of Cp we should take? I guess for air Cp at high altitudues (100..200 km, where we can expect free molecular flow) is different from usual 1006 J/kg/K?

I think the stagnation temperature does not make sense in free molecular flow where a size of object (e.g. satelite) is much less than the molecular mean free path. There is always a sleep velocity between fluid and an object.

Angen

Yes, that's what makes me curious! But in DSMC codes and papers (like ones of Bird) the dimensionless wall temperature is expressed in terms of flow and temperature and stagnation temperature! So I wonder what does this stagnation temperature meens.