Molecular interpretation of nonclassical gas dynamics of dense vapors under the van der Waals model

Molecular interpretation of nonclassical gas dynamics of dense vapors under the van der Waals model

Colonna, P.
Guardone, A.

Mechanical, Maritime and Materials Engineering

Process and Energy

2006-05-16

The van der Waals polytropic gas model is used to investigate the role of attractive and repulsive intermolecular forces and the influence of molecular complexity on the possible nonclassical gas dynamic behavior of vapors near the liquid-vapor saturation curve. The decrease of the sound speed upon isothermal compression is due to the well-known action of the van der Waals attractive forces and this effect is shown here to be comparatively larger for more complex molecules with a large number of active vibrational modes; for these fluids isentropic flows are in fact almost isothermal. Contributions to the speed of sound resulting from intermolecular forces and the role of molecular complexity are analyzed in details for both isothermal and isentropic transformations. Results of the exact solution to the problem of a finite pressure perturbation traveling in a still fluid are presented in three exemplary cases: ideal gas, dense gas and nonclassical gas behavior. A classification scheme of fluids based on the possibility of exhibiting different gas dynamic behaviors is also proposed.

aerodynamics, van der Waals forces
isothermal transformations
two-phase flow
vibrational modes
acoustic wave velocity

http://resolver.tudelft.nl/uuid:0ad00bed-2ec6-40ab-a651-484da120ae2c

https://doi.org/10.1063/1.2196095

American Institute of Physics

1070-6631

http://link.aip.org/link/PHFLE6/v18/i5/p056101/s1

Physics of Fluids, 18 (5), 2006

Institutional Repository

journal article

(c) 2006 The Author(s)
American Institute of Physics