Nonbarotropic version of the Trusdell maximum principle

For stationary nonbarotropic flows of an ideally perfect gas using the Munk - Prim transformations, the Truesdell’s maximum principle for the pressure valid for barotropic flows is extended to nonbarotropic flows. Therefore, in the conditions of the (barotropic) Truesdell’s maximum principle for the pressure appears to be sufficient to replace the Q-parameter for the velocity of the considered flow by the Q-parameter for the same velocity, multiplied by some (properly selected) entropy function. It is shown that in the case of strict inequalities Q Q > 0 in a certain neighborhood of the extremum point, Truesdell’s classical maximum principle for the pressure is valid even in non-barotropic flows.