In this paper, we derive several new sufficient conditions of the non-breakdown of strong solutions for both the 3D heat-conducting compressible Navier-Stokes system and nonhomogeneous incompressible Navier-Stokes equations. First, it is shown that there exists a positive constant
ε such that the solution
(ρ,u,θ) to the full compressible Navier-Stokes equations can be extended beyond
t=T provided that one of the following two conditions holds:
(1)
ρ∈L∞(0,T;L∞(R3)),
u∈Lp,∞(0,T;Lq,∞(R3)) and
‖u‖Lp,∞(0,T;Lq,∞(R3))≤ε, with 2/p+3/q=1, q>3;
(2)
λ<3μ, ρ∈L∞(0,T;L∞(R3)),
θ∈Lp,∞(0,T;Lq,∞(R3)) and
‖θ‖Lp,∞(0,T;Lq,∞(R3))≤ε, with 2/p+3/q=2, q>3/2.
To the best of our knowledge, this is the first continuation theorem allowing the time direction to be in Lorentz spaces for the compressible fluid. Second, we establish some blow-up criteria in anisotropic Lebesgue spaces for the finite blow-up time
T∗:
(1) assuming that the pair
(p,→q) satisfies
2/p+1/q1+1/q2+1/q3=1 (1<qi<∞) and (1.17), then
lim supt→T∗(‖ρ‖L∞(0,t;L∞(R3))+‖u‖Lp(0,t;Lq11Lq22Lq33(R3)))=∞;
(2) letting the pair
(p,→q) satisfy
2/p+1/q1+1/q2+1/q3=2 (1<qi<∞) and (1.17), then
lim supt→T∗(‖ρ‖L∞(0,t;L∞(R3))+‖θ‖Lp(0,t;Lq11Lq22Lq33(R3)))=∞,(λ<3μ).
Third, without the condition on
ρ in (0.1) and (0.3), the results also hold for the 3D nonhomogeneous incompressible Navier-Stokes equations. The appearance of a vacuum in these systems could be allowed.