From quasi-incompressible to semi-compressible fluids

<p style='text-indent:20px;'>A new concept of semi-compressible fluids is introduced for slightly compressible visco-elastic (typically rather liquids than gasses) where mass density variations are negligible in some sense, while being directly controlled by pressure which very small comparison with the elastic bulk modulus. The physically consistent fully Eulerian models specific dispersion pressure-wave speed devised. This contrasts to so-called quasi-incompressible described not consistently and, fact, only approximate ideally incompressible ones limit. After surveying and modifying fluids, we eventually devise convective complying energy conservation capturing phenomena as propagation wave-length (and possibly also pressure) dependent velocity.</p>