arXiv2026
For the degenerate viscous and heat conductive compressible fluids, the momentum equations and the energy equation are degenerate both in the time evolution and spatial dissipation when vacuum appears, and then the physical entropy S behaves singularly, which make it challenging to study the corresponding existence of regular solutions with high order regularities of S near the vacuum. In this paper, for the physically important case that the coefficients of viscosities and heat conductivity depend on the absolute temperature θin a power law of Chapman-Enskog, we establish the local existence of the unique regular solution with far field vacuum to the Cauchy problem of the 3-D full CNS. In our analysis, the corresponding vacuum problem is formulated in terms of the density ρ, velocity u and S instead of (ρ, u,θ), which makes it possible to compare the orders of the degeneracy of the time evolution and the spatial dissipations near the vacuum in terms of the powers of ρ. However, for heat conductive fluids, both a degenerate spatial dissipation and a source term related to \triangle ρ^{γ-1}, will appear in the time evolution equation for S, which makes it formidable to study the propagation of regularities of S. Fortunately, we can choose proper weights to control the dynamics of (ρ, u,S) by introducing an enlarged reformulated system, which provides an effective propagation mechanism for S's high order regularities near the vacuum.