A computer model for improving the potentialities of the parallel wires anemometers is presented. A new calculation technique has been developed, taking into account the diffusion effects in the transfer phenomena that occur during the measurement procedure. A numerical model which represents the behaviour of a unique wire in relaxation has been developed. It has been shown that, for the range of speeds encountered in natural convection, the phase of relaxation could be separated into two periods. During the first period the diffusion transfer is dominant, whereas in the second period the convection transfer becomes more significant. Moreover, the energy of the emitter wire is introduced as a source term in a transport model built upon the Patankar＇s method. The validity of the prediction is illustrated by comparison with measurements and very good agreement has been achieved. reserved.