We present in this report two modelizations of vibrational relaxation processes in a gaz: the Landau-Teller (LT) model and the master equations (ME). We give different models for VT and VV rate constants. We propose an algorithm to solve the equations of vibrational relaxation (LT or ME) coupled with conservation equations of momentum and total energy. Both models are compared on the computations of the flows around an infinite cylinder, at different Mach numbers.