51. Physics of gases
51.10.+y Kinetic and transport theory of gases
51.20.+d Viscosity, diffusion, and thermal conductivity
51.30.+i Thermodynamic properties, equations of state
51.35.+a Mechanical properties; compressibility
51.40.+p Acoustical properties: (see also 43.28 Aeroacoustics, atmospheric
sound; for ultrasonic relaxation in gases, see 43.35.F in acoustic
appendix)
51.50.+v Electrical properties (ionization, breakdown, electron and ion
mobility, etc.): (see also 52.80 Electric discharges)
51.60.+a Magnetic properties
51.70.+f Optical and dielectric properties
51.90.+r Other topics in the physics of gases