Characteristic surfaces in gas flows

Traveling wave with allowance for equilibrium radiation

“…Indeed, under the Zemplén theorem, D > c(ρ 0 , T 0 ). Then, in view of relation(8), we obtain the chain of inequalitiesD > c(ρ 0 , T 0 ) > c κ (ρ 0 , T 0 ),which implies the evolutionarity of the flow ahead of the traveling-wave front. It should be noted that the need to satisfy the Zemplén theorem in the case of a non-heat-conducting gas [D > c(ρ 0 , T 0 )] determines the value D 0 = c(ρ 0 , T 0 ).…”

“…For this system, there are two sound C ± κ -characteristics [8] whose propagation velocity relative to the flow is equal to the sound velocity in the heat-conducting inviscid gas c κ :…”

“…However, there are examples of flows (see [8,11]) where weak perturbations produced by a smooth displacement of an impermeable piston in a homogeneous gas of nonzero temperature propagate over a homogeneous background at a constant velocity c κ and do not lead to an infinite propagation velocity of the thermal heterogeneity. This effect arises when on the compressing piston there is a heat drain under a special law.…”