Isentropic flow

An isentropic flow has constant entropy along the fluid and contains no entropy-producing shocks or dissipation. For a perfect gas, $p/{\rho }^{\gamma }$ is constant and $c_s^2=\gamma p/\rho \propto {\rho }^{\gamma -1}$.

A homentropic flow has one spatially uniform entropy value throughout the fluid. It is therefore isentropic along every fluid trajectory, and its pressure can be treated as a single-valued function of density.