Foundation of potential flows

The fundamental equations governing the motion of perfect fluid are presented in this section. Specifically, continuity equation, Euler equations, and entropy equation are obtained starting from the fundamental principles of conservation of mass, momentum and energy, along with Gibbs thermodynamics with the restriction that fluid is perfect (that is, inviscid and adiabatic). These equations are used to prove that, if a flow field is initially isentropic and irrotational and no shocks arise, then the field remains irrotational, except for the points emanating from the trailing edge (wake). The equation for the velocity potential is then obtained.