Computation of Fictitious Gas Flow with Euler Equations

The Fictitious Gas Concept supports some computational design methods to construct shock-free transonic flows. It was originally developed for potential flows, here it is introduced to the Euler equations for more general applications. A new equation of state needs to be defined in order to simulate results of the simpler potential approach. An operational numerical Euler code was chosen for the modifications and tested on a basic boundary value problem: The inviscid flow past a circular cylinder with a local supersonic flow region. The numerical computation is based on a finite volume method to solve the time dependent Euler equations in integral form. Conclusions are drawn for a physical explanation of the hitherto abstract “fictitious” gas: an internal momentum and energy supply/removal is modelled and the results for locally nonisentropic flow may be interpreted as an internal cooling / heating process controlled by the local flow velocity.