A solution of the wave equations using real gases

Solutions of the equations of compressible flow, which result in the passage of waves through the fluid, usually make the assumption that the gas is a perfect one. This means that the energy terms and the wave-propagation velocities are inextricably coupled in an unrealistic manner. This paper describes a finite difference solution of the wave equations in which the fluid is not a perfect gas, but one in which the properties of internal energy and enthalpy are related to the composition of the mixture by the Gibbs-Dalton Law, and the temperature by a set of polynomial expressions. Such a calculation technique has the potential to be applied to the intake and exhaust manifolds of internal combustion engines, and it could also be expanded to other fluids which do not act as perfect gases, e.g. steam.