Electronic Journal of Differential Equations, Vol. 2025 (2025), No. 74, pp. 1–18. ISSN: 1072-6691. URL: https://ejde.math.txstate.edu, https://ejde.math.unt.edu DOI: 10.58997/ejde.2025.74 ZERO-VISCOSITY-CAPILLARITY LIMIT FOR THE CONTACT DISCONTINUITY FOR THE 1-D FULL COMPRESSIBLE NAVIER-STOKES-KORTEWEG EQUATIONS JIAXUE CHEN, YEPING LI, RONG YIN Abstract. In this article, we study the zero-viscosity-capillarity limit problem for the one- dimensional full compressible Navier-Stokes-Korteweg equations. This equation models com- pressible viscous fluids with internal capillarity and heat conductivity. We prove that if the solution of the inviscid Euler equations is piecewise constants with a contact discontinuity, then there exist smooth solutions to the one-dimensional full compressible Navier-Stokes-Korteweg system which converge to the inviscid solution away from the contact discontinuity. It converges a rate of ϵ1/4 as the the viscosity µ = ϵ, heat-conductivity coefficient α = νϵ and the capillarity κ = λϵ2 and ϵ tends to zero. The proof is completed using the energy method and the scaling technique. 1. Introduction The purpose of this paper is to study the asymptotic equivalence between the solutions of the one-dimensional full compressible Navier-Stokes-Korteweg equations and those of the compressible full Euler system when the viscosity, the heat-conductivity coefficient and the capillarity satisfy some conditions. The one-dimensional full compressible Navier-Stokes-Korteweg (denoted as NSK in the sequel) equations in Lagrangian coordinates are expressed as vt − ux = 0, ut + px = µ (ux v ) x + κ v (1 v (1 v (1 v ) x ) x ) x ,( e+ u2 2 ) t + (pu)x = α (θx v ) x + ( µ uux v + κu ( 1 v2 (1 v (1 v ) x ) x − 1 2 (1 v (1 v ) x )2)) x , (1.1) where v, u, θ, p and e denote the specific volume, the velocity, the temperature, the pressure, and the internal energy, respectively, and µ, α and κ are the viscosity and heat-conductivity and capillary coefficients, respectively. Here x is the Lagrangian coordinate, so that x = constant corresponds to a particle path. Here we only study the ideal polytropic gas, so that the pressure p and the internal energy e are related with v and θ by the following equations of state p = R θ v , e = R γ − 1 θ + constant, (1.2) where R > 0 is the gas constant and γ ∈ (1, 2] is the adiabatic exponent. System (1.1) is known to be a model system for two phase flow with phase transition between liquid and vapor in compressible fluid. Based on the works of Van der Waals [27] and Korteweg [17], the rigorous derivation of the corresponding equations is due to Dunn and Serrin [8] and Heida and Málek [13], respectively. Finally, one can see easily that when κ = 0, the system (1.1) is reduced to the classical compressible Navier-Stokes equation. 2020 Mathematics Subject Classification. 76W05, 35B40. Key words and phrases. Full compressible Navier-Stokes-Korteweg equation; compressible Euler system; zero-viscosity-capillarity limit; contact discontinuity. ©2025. This work is licensed under a CC BY 4.0 license. Submitted May 19, 2025. Published July 16, 2025. 1 2 J. CHEN, Y. LI, R. YIN EJDE-2025/74 The compressible NSK equations have attracted a lot of attention of physicists and math- ematicians because of its physical importance, complexity, rich phenomena, and mathematical challenges. Here we only refer to some study results about the full compressible NSK equations (1.1). Hattori and Li [12] considered the local existence and global existence of smooth solution for three-dimensional non-isentropic compressible NSK equations in Sobolev space. Haspot [11] showed the existence results of strong solutions to the nonisothermal compressible NSK equa- tions in R3. Chen, He and Zhao [3] obtained the global classical solutions of the one dimensional full compressible NSK equations with large initial data. Hou, Peng and Zhu [15] got the global classical solutions for the three-dimensional non-isentropic compressible NSK equation with small initial energy. Chen and Zhao [7] discussed the existence, uniqueness and nonlinear stability of stationary solutions to the Cauchy problem of the three-dimensional full compressible NSK equations. Cai, Tan and Xu [1] established the existence of the time periodic solution to the three-dimensional full compressible NSK equations with a sufficiently small external force which is periodic in the time variable. Zhang and Tan [31] showed decay estimates of smooth solutions for the non-isentropic compressible fluid models of Korteweg type in R3. Kotschote [18, 19, 20] established the local existence of strong solution, and global existence and time-asymptotics of strong solution of the non-isentropic compressible NSK equations in a bounded domain with C3- boundary. About the stability of basic nonlinear wave patterns such as the discontinuity wave, viscous contact wave and the rarefaction wave of one dimensional compressible NSK equations, we can refer to [4, 5, 6, 9, 24, 26] and the references therein. Moreover, vanishing viscosity limit is one of the important problems in the theory of com- pressible fluids. Goodman and Xin [10] and Hoff and Liu [14] pioneered, respectively, the study on the viscous limit of piecewise smooth solutions for the hyperbolic conservation law, and on the vanishing viscosity limit of the viscous compressible isentropic Navier-Stokes equations for piecewise constant shock. After these work, the limit problem of the system of hyperbolic con- servation laws and of the compressible Navier-Stokes equations is an important problem and has been extensively investigated by many authors for the cases that the solution of the inviscid flows is smooth, or contains singularities such as shocks and the vacuum state. Since the compressible NSK equations are the capillarity approximation of the classical compressible Navier-Stokes equa- tions (see [16]), one of the important topics about the compressible NSK equations is to study the zero-viscosity-capillarity limit. Charve and Haspot [2] proved the existence of the global strong solution of the one-dimensional isentropic NSK equations, and then showed that the global strong solution converges to a weak-entropy solution of the compressible Euler equations. Li and Luo [22], and Li and Zhu [23] showed zero-viscosity-capillarity limit towards rarefaction wave without and with vacuum for one-dimensional the compressible NSK equations, respectively. Yin and Li [29] also discussed the zero-viscosity-capillarity limit towards planar rarefaction wave for the two- dimensional isentropic NSK equations. Nevertheless, it is more significant and difficult to study the viscosity-vanishing limit for the non-isentropic (full) NSK equation (1.1) from both physical and mathematical points of view. Lastly, Wang and Yao [28], and Yin, Li and Qian [30] discussed zero-viscosity-capillarity limit towards rarefaction wave for one-dimensional full NSK system, re- spectively. Here, we are going to investigate the zero-viscosity-capillarity limit problem for the one-dimensional full compressible NSK equations (1.1). For this, we assume that the coefficients of viscosity, capillary, heat-conductivity µ, κ and α satisfy µ = ϵ, κ = λϵ2, α = νϵ. (1.3) Then, formally as ϵ→ 0, (1.1) becomes the well-known compressible Euler system vt − ux = 0, ut + px = 0,( e+ u2 2 ) t + (pu)x = 0. (1.4) EJDE-2025/74 SHORT ZERO-VISCOSITY-CAPILLARITY LIMIT 3 Further, the Riemann problem to the corresponding Euler system (1.4) with Riemann initial data (v, u, θ)(0, x) = { (v−, u−, θ−), if x < 0, (v+, u+, θ+), if x > 0, (1.5) where v±(> 0), u±, s± are given constants, has a contact discontinuity (see [21]), which takes the form (V̄ , Ū , Θ̄)(t, x) = { (v−, u−, θ−), if x < 0, (v+, u+, θ+), if x > 0, (1.6) provided that u− = u+, p− = Rθ− v− = Rθ+ v+ = p+. (1.7) As in [25], we first construct the viscous contact wave (V CD, UCD,ΘCD)(t, x) as follows. Let the pressure of the profile (V CD, UCD,ΘCD)(t, x) be almost constant, that is, PCD = R ΘCD V CD ≈ p+ = p−, (1.8) it indicates that the energy equation (1.1)3 is R γ − 1 Θt + p+Ux = α (Θx V ) x . (1.9) Substituting (1.8) into (1.9) and using (1.1)1 yield a nonlinear diffusion equation Θt = aα( Θx Θ )x, Θ(t,±∞) = θ±, a = p+(γ − 1) R2γ > 0, which admits a unique self-similar solution Θ̂(t, x) = Θ̂ ( x√ 1 + t ) . Furthermore, Θ̂(t, x) is a monotone function, increasing if θ+ > θ− and decreasing if θ+ < θ−. Let δCD = |θ+ − θ−|, then Θ̂(t, x) satisfies |(ϵ(1 + t)) k 2 ∂kxΘ̂|+ |Θ̂(t, x)− θ±| ≤ CδCDe− c0x2 ϵ(1+t) , as |x| → ∞, k ≥ 1. (1.10) With Θ̂(t, x) so determined, we can define the contact wave profile (V CD, UCD,ΘCD)(t, x) as follows: V CD = RΘ̂ p+ , UCD = u− + α(γ − 1) Rγ Θ̂x Θ̂ , ΘCD = Θ̂. (1.11) Then (V CD, UCD,ΘCD) satisfies ∥V CD − V̄ , UCD − Ū ,ΘCD − Θ̄∥Lp = O(ϵ 1 2p )(1 + t) 1 2p , p ≥ 1, (1.12) and V CD t − UCD x = 0, UCD t + PCD x = ϵ( UCD x V CD )x +RCD 1 , R γ − 1 ΘCD t + PCDUCD x = α( ΘCD x V CD )x + ϵ (UCD x )2 V CD +RCD 2 , (1.13) where RCD 1 = O(δCD)ϵ1/2(1 + t)− 3 2 e− c0x2 ϵ(1+t) , RCD 2 = O(δCD)ϵ(1 + t)−2e− c0x2 ϵ(1+t) , as |x| → ∞. Now we state our main results in the following theorem. 4 J. CHEN, Y. LI, R. YIN EJDE-2025/74 Theorem 1.1. For a given (v−, u−, θ−), suppose that (v+, u+, θ+) satisfies (1.7). Let (V̄ , Ū , Θ̄)(t, x) be a contact discontinuity solution of the form (1.6) with finite strength to the Euler system (1.4). Then, there exists constant ϵ0 > 0, such that for each ϵ ∈ (0, ϵ0], there is a smooth solution (v, u, θ) to (1.1) on R× R+, with the same initial data as (V CD, UCD,ΘCD), satisfying (v − V̄ , u− Ū , θ − Θ̄) ∈ C0(0,+∞;L2), (v, u, θ)x ∈ C0(0,+∞;L2), vxx ∈ C0(0,+∞;L2), (u, θ)xx ∈ L2(0,+∞;L2), vxxx ∈ L2(0,+∞;L2). Moreover, for each arbitrarily large T > 0 and small h > 0, it holds that sup 0≤t≤T ∥(v − V̄ , u− Ū , θ − Θ̄)(t, ·)∥2 ≤ Cϵ1/2, (1.14) sup 0≤t≤T, |x|≥h |(v − V̄ , u− Ū , θ − Θ̄)(t, ·)| ≤ Cϵ1/4. (1.15) Remark 1.2. Theorem 1.1 shows the zero-viscosity-capillarity limit of the one-dimensional full NSK equations with the same order of the viscosity and the heat-conductivity, and the higher order capillarity, as the corresponding full Euler equations have a contact discontinuity. It is more interest to study the limit for the one-dimensional full NSK equations as the viscosity, the heat- conductivity and the capillarity have same order. Further, it is also important that we investigate the limit with the heat-conductivity and the capillarity and without the viscosity as in [25]. Finally, the convergence rate in (1.15) may not be optimal. We conjecture that it can be improved to be ϵ1/2. These will be left for future study. The remaining part of this paper is organized as follows. In Section 2, we reformulate the problem and give the proof of Theorem 1.1. We also collect the a priori estimates needed in the proof of our main theorem, in Proposition 2.1. Then, we establish the a-priori estimates for the reformulated problem in Section 3. Notation. Throughout this paper, c and C denote two universal positive constant which is independent of time t and may vary from line to line. Lp(R)(1 ≤ p < ∞) are the spaces of measurable functions whose p-powers are integrable on R, with the norm ∥ · ∥Lp = (∫ R | · |pdx ) 1 p . For the case that p = 2, we simply denote ∥ · ∥L2 by ∥ · ∥. And L∞(R) is the space of bounded measurable functions on R, with the norm ∥ ·∥L∞ = ess supx∈R| · |. Furthermore, for a nonnegative integer k, Hk(R) denotes the usual L2-type Sobolev space of order k. We write ∥ · ∥k for the standard norm of Hk(R). Finally, we denote by C([0, T ];Hk(R)) (resp. L2(0, T ;Hk(R))) the space of continuous (resp. square integrable) functions on [0, T ] with values taken in a Banach space Hk(R). 2. Reformulation of the Problem and Proof of Theorem 1.1 In this section, we reformulate the original problem (1.1) and (1.5) in terms of the perturbated variables, then give the proof of Theorem 1.1. To begin with, suppose that U ≡ (v, u, θ) is the exact solution to (1.1) with the initial data U(x, 0) = (V CD, UCD,ΘCD)(x, 0), and define the perturbated variables: ϕ = v − V CD, ψ = u− UCD, ζ = θ −ΘCD. Let y = x ϵ , τ = 1 + t ϵ , then from (1.1) and (1.13), one sees that ϕτ − ψy = 0, ψτ + (p− PCD)y = (uy v − UCD y V CD ) y + λ v (1 v (1 v (1 v ) y ) y ) y −R1, R γ − 1 ζτ + (puy − PCDUCD y ) = ν (θy v − ΘCD y V CD ) y + (u2y v − (UCD y )2 V CD ) + λuy (5v2y 2v6 − vyy v5 ) −R2, (2.1) EJDE-2025/74 SHORT ZERO-VISCOSITY-CAPILLARITY LIMIT 5 with the initial data ϕ(τ0, y) = ψ(τ0, y) = ζ(τ0, y) = 0, (2.2) where τ0 = 1 ϵ , R1 = ϵRCD 1 , R2 = ϵRCD 2 and |∂kyV CD|+ |∂kyΘCD| ≤ Cϵ k 2 e−c0y 2/τ , |∂k−1 y UCD| ≤ C|∂kyΘCD|, k ≥ 1 |R1| ≤ Cϵ3/2e−c0y 2/τ , |R2| ≤ Cϵ2e−c0y 2/τ . (2.3) Set τ1 = T+1 ϵ . Then we only need to show that for suitably small ϵ, the Cauchy problem (2.1) and (2.2) has a unique ”small” smooth solution on R × [τ0, τ1]. By the standard existence and uniqueness theory (cf. [12]), and the continuous induction argument, it suffices to show the following a priori estimate. Proposition 2.1. Suppose that the problem (2.1) and (2.2) has a solution (ϕ, ψ, ζ) ∈ C0(τ0, τ2;L 2) for some τ2 ∈ (τ0, τ1]. Then there exist positive constants ϵ1, η1 and C, independent of ϵ, such that if 0 < ϵ ≤ ϵ1, sup τ0≤τ≤τ2 (∥ϕ∥2 + ∥(ψ, ζ)∥1) ≤ η1 (2.4) for small ϵ1 and η1, then sup τ0≤τ≤τ2 ∥(ϕ, ψ, ζ, ϕy)(τ)∥2 + ∫ τ2 τ0 ∥(ϕy, ψy, ζy, ϕyy)∥2 dτ ≤ Cϵ1/2, (2.5) and sup τ0≤τ≤τ2 ∥(ϕy, ψy, ζy, ϕyy)(τ)∥2 + ∫ τ2 τ0 ∥(ϕyy, ψyy, ζyy, ϕyyy)∥2 dτ ≤ Cϵ2/3. (2.6) Suppose that Proposition 2.1 is true, we then are in a position to prove Theorem 1.1 as follows. Proof of Theorem 1.1. For any T > 0, in view of (2.5), we have sup 0≤t≤T ∥(v − V CD, u− UCD, θ −ΘCD)(t)∥2 = ϵ sup τ0≤τ≤τ1 ∥(v − V CD, u− UCD, θ −ΘCD)(τ)∥2 ≤ Cϵ3/2. Then it follows from this and (1.12) that sup 0≤t≤T ∥(v − V̄ , u− Ū , θ − Θ̄)(t)∥2 ≤ sup 0≤t≤T ∥(v − V CD, u− UCD, θ −ΘCD)(t)∥2 + sup 0≤t≤T ∥(V CD − V̄ , UCD − Ū ,ΘCD − Θ̄)(t)∥2 ≤ Cϵ1/2, which gives (1.14). Finally, ∥(v − V CD, u− UCD, θ −ΘCD)(t)∥L∞ ≤ C∥(ϕ, ψ, ζ)(t)∥1/2∥(ϕy, ψy, ζy)(t)∥1/2 ≤ Cϵ1/4. This, together with (1.10), yields (1.15). Hence we have completed the proof of Theorem 1.1. □ 3. A priori estimate In this section, we shall prove Proposition 2.1. First, notice that the smallness of η1 in (2.4) guarantees that 2v+ ≥ v = V CD + ϕ ≥ v− 2 , 2θ̄ ≥ θ = ΘCD + ζ ≥ θ 2 , (3.1) where θ = inft≥0, x∈R ΘCD(t, x) and θ̄ = supt≥0, x∈R ΘCD(t, x). For the sake of clarity, we will divide the proof of Proposition 2.1 into some Lemmas. That is, Proposition 2.1 can be obtained by the following Lemmas 3.1-3.3. 6 J. CHEN, Y. LI, R. YIN EJDE-2025/74 First, we establish the first energy estimate for the unknown variable (ϕ, ψ, ζ)(t, x) to problem (2.1)-(2.2). For this, let us introduce the function Φ(s) = s− ln s−1, which is the convex function for any s > 0. Then from (2.1), after a direct and tedious computation, we arrive at(1 2 ψ2 + λ ϕ2y 2v5 +RΘCDΦ ( v V CD ) + RΘCD γ − 1 Φ ( θ ΘCD )) τ + ψ2 yΘ CD vθ + ν ζ2yΘ CD vθ2 + ( (p− PCD)ψ − (uy v − UCD y V CD ) ψ − λ 1 v2 (1 v (1 v ) y ) y ψ − λ ϕyψy v5 + λ v2yψ 2v6 − ν (θy v − ΘCD y V CD )ζ θ ) y + PCDUCD y ( γΦ ( v V CD ) +Φ (θV CD vΘCD )) = ( ν (ΘCD y V CD ) y + (UCD y )2 V CD +R2 )( (γ − 1)Φ ( v V CD ) − Φ (ΘCD θ )) + UCD y vV CD ϕψy + ν ΘCD y vθ2 ζζy + ν ΘCDΘCD y vθ2V CD ϕζy − ν (ΘCD y )2 vθ2V CD ϕζ + 2UCD y vθ ζψy − (UCD y )2 vθV CD ϕζ − λ 5UCD y 2v6 ϕ2y + λ V CD yy v5 ψy − λ 5(V CD y )2 2v6 ψy + λ(ψy + Uy) (5(ϕy + Vy) 2 2v6 − ϕyy + Vyy v5 )ζ θ −R1ψ −R2 ζ θ . (3.2) Here we used 1 v (1 v (1 v (1 v ) y ) y ) y ψ = ( 1 v2 (1 v (1 v ) y ) y ψ ) y + (vy v3 ) y ψy v2 − 2 (vy v3 ) y ψvy v3 = ( 1 v2 (1 v (1 v ) y ) y ψ + vyψy v5 − 2 ψv2y v6 ) y − ( ϕ+ V CD ) y ψyy v5 + 4(ϕy + V CD y )2ψy v6 + 2 ψvyvyy v6 − 6ψv3y v7 = ( 1 v2 (1 v (1 v ) y ) y ψ + vyψy v5 − 2 ψv2y v6 − V CD y ψy v5 + v2yψ v6 ) y − ( ϕ2y 2v5 ) τ − 5ϕ2yU CD y 2v6 + V CD yy ψy v5 − 5ψy(V CD y )2 2v6 with the help of (2.1)1. Moreover, there exists a positive constant C1 and C2 such that C1(s− t)2 ≤ Φ (s t ) ≤ C2(s− t)2. (3.3) Lemma 3.1. Suppose that the assumptions in Proposition 2.1 hold. Then it holds that sup τ0≤τ≤τ2 ∥(ϕ, ψ, ζ, ϕy)(τ)∥2 + ∫ τ2 τ0 ∥(ϕy, ψy, ζy, ϕyy)∥2 dτ ≤ Cϵ1/2. (3.4) Proof. Integrating (3.2) with respect to τ and y over [τ0, τ ] × R (τ ≤ τ2) and using (1.3), (3.1) and (3.3) shows that ∥(ϕ, ψ, ζ, ϕy)(τ)∥2 + ∫ τ τ0 ∥∥∥√UCD y (ϕ, ζ) ∥∥∥2 dτ + ∫ τ τ0 ∥(ψy, ζy)∥2 dτ ≤ C 6∑ i=1 ∫ τ τ0 ∫ R Hidydτ, (3.5) where H1 = |UCD y V CD yy ζ|+ |UCD y (V CD y )2ζ|+ |R1ψ|+ |R2ζ|, H2 = (|ΘCD yy |+ |ΘCD y V CD y |+ (UCD y )2 + |UCD y |)(ϕ2 + ζ2) + |(ΘCD y )2ϕζ|+ |(UCD y )2ϕζ|+ |R2|(ϕ2 + ζ2), H3 = |UCD y ϕψy|+ |ΘCD y ζζy|+ |ΘCD y ϕζy|+ |UCD y ζψy|+ |(V CD y )2ζψy| + |UCD y V CD y ζϕy|+ |V CD yy ζψy|+ |UCD y ζϕyy|, H4 = |V CD yy ψy|+ |(V CD y )2ψy|+ |UCD y ϕ2y|, EJDE-2025/74 SHORT ZERO-VISCOSITY-CAPILLARITY LIMIT 7 H5 = |V CD y ζϕyψy|+ |UCD y ζϕ2y|, H6 = |ζψyϕyy|+ |ζψyϕ 2 y|. Now let us estimate each term on the right hand side of (3.5). First, we employ Young inequality and (2.3) to obtain ∫ τ τ0 ∫ R |UCD y V CD yy ζ|dydτ ≤ ϵ ∫ τ τ0 ∫ R |ζ|2 dydτ + ϵ−1 ∫ τ τ0 ∫ R |UCD y V CD yy |2 dydτ ≤ ϵ ∫ τ τ0 ∫ R |ζ|2 dydτ + Cϵ−1 ∫ τ τ0 ∫ R ( ϵe−c0y 2/τ · ϵe−c0y 2/τ )2 dydτ ≤ ϵ ∫ τ τ0 ∥ζ∥2 dτ + Cϵ3 ∫ τ τ0 ∫ R e− 4c0y2 τ dydτ ≤ ϵ ∫ τ τ0 ∥ζ∥2 dτ + Cϵ3 ∫ τ τ0 τ1/2 dτ ≤ ϵ ∫ τ τ0 ∥ζ∥2 dτ + Cϵ3/2. (3.6) Similarly, estimating the rest terms in ∫ τ τ0 ∫ RH1dydτ , we have ∫ τ τ0 ∫ R H1dydτ ≤ ϵ ∫ τ τ0 (∥ψ∥2 + ∥ζ∥2) dτ + C ( ϵ1/2 + ϵ3/2 ) . (3.7) Next, utilizing Young inequality, (2.3) and e−c0y 2/τ ≤ 1, one gets ∫ τ τ0 ∫ R |(ΘCD y )2ϕζ|dydτ ≤ C ∫ τ τ0 ∫ R ( ϵ1/2e−c0y 2/τ )2 (ϕ2+ζ2) dydτ ≤ Cϵ ∫ τ τ0 (∥ϕ∥2+∥ζ∥2) dτ. (3.8) In the same way, we can deal with the remainder terms in ∫ τ τ0 ∫ RH2dydτ and the terms in∫ τ τ0 ∫ RH3dydτ to obtain ∫ τ τ0 ∫ R H2dydτ ≤ C(ϵ+ ϵ2) ∫ τ τ0 (∥ϕ∥2 + ∥ζ∥2) dτ, (3.9) and ∫ τ τ0 ∫ R H3dydτ ≤ C ( ϵ1/2 + ϵ ) ∫ τ τ0 ∥ϕ∥2 dτ + C ( ϵ1/2 + ϵ+ ϵ3/2 ) ∫ τ τ0 ∥ζ∥2 dτ + Cϵ ∫ τ τ0 ∥ψy∥2 dτ + Cϵ1/2 ∫ τ τ0 ∥ζy∥2 dτ + Cϵ3/2 ∫ τ τ0 ∥ϕy∥2 dτ + Cϵ ∫ τ τ0 ∥ϕyy∥2 dτ. (3.10) With (3.6) and (3.8) in hand, it is easy to obtain ∫ τ τ0 ∫ R H4dydτ ≤ 1 8 ∫ τ τ0 ∥ψy∥2 dτ + Cϵ ∫ τ τ0 ∥ϕy∥2 dτ + Cϵ1/2. (3.11) 8 J. CHEN, Y. LI, R. YIN EJDE-2025/74 Moreover, using (2.3), Hölder inequality, Sobolev inequality, (2.4) and Young inequality, and noting e−c0y 2/τ ≤ 1, one obtains∫ τ τ0 ∫ R H5dydτ ≤ C ∫ τ τ0 ∫ R (∣∣ϵ1/2e−c0y 2/τζϕyψy ∣∣+ ∣∣ϵe−c0y 2/τζϕ2y ∣∣) dydτ ≤ C ∫ τ τ0 ( ϵ1/2∥ζ∥L∞∥ϕy∥∥ψy∥+ ϵ∥ζ∥L∞∥ϕy∥2 ) dτ ≤ C ∫ τ τ0 ( ϵ1/2∥ζ∥1∥ϕy∥∥ψy∥+ ϵ∥ζ∥1∥ϕy∥2 ) dτ ≤ C ∫ τ τ0 ( ϵ1/2η1∥ϕy∥∥ψy∥+ ϵη1∥ϕy∥2 ) dτ ≤ C ( ϵ1/2 + ϵ ) η1 ∫ τ τ0 ∥ϕy∥2 dτ + Cϵ1/2η1 ∫ τ τ0 ∥ψy∥2 dτ. (3.12) Finally, it follows from Hölder inequality, Sobolev inequality, Young inequality and (2.4), that∫ τ τ0 ∫ R H6dydτ ≤ C ∫ τ τ0 (∥ϕy∥2L∞∥ψy∥∥ζ∥+ ∥ζ∥L∞∥ϕyy∥∥ψy∥) dτ ≤ C ∫ τ τ0 (∥ϕy∥∥ϕyy∥∥ψy∥∥ζ∥+ ∥ζ∥1∥ϕyy∥∥ψy∥) dτ ≤ C(η1 + η21) (∫ τ τ0 ∥ψy∥2 dτ + ∫ τ τ0 ∥ϕyy∥2 dτ ) . (3.13) Therefore, substituting the estimates of (3.7), (3.9), (3.10), (3.11), (3.12) and (3.13) into (3.5) and noting that ϵ and η1 are suitably small, we have ∥(ϕ, ψ, ζ, ϕy)(τ)∥2 + ∫ τ τ0 ∥∥∥√UCD y (ϕ, ζ) ∥∥∥2 dτ + ∫ τ τ0 ∥(ψy, ζy)∥2 dτ ≤ Cϵ ∫ τ τ0 ∥ψ∥2 dτ + C ( ϵ1/2 + ϵ+ ϵ3/2 + ϵ2 ) ∫ τ τ0 ∥ζ∥2 dτ + C ( ϵ1/2 + ϵ+ ϵ2 ) ∫ τ τ0 ∥ϕ∥2 dτ + C ( ϵ+ η1 + η21 ) ∫ τ τ0 ∥ϕyy∥2 dτ + C ( ϵ+ ϵ3/2 + ( ϵ1/2 + ϵ ) η1 ) ∫ τ τ0 ∥ϕy∥2 dτ + C ( ϵ1/2 + ϵ3/2 ) . (3.14) Next, we deal with the double integral of ϕ2y and ϕ2yy. We multiply (1.13)2 by ϕy v to obtain( ϕ2y 2v2 − ψ ϕy v ) τ + ( λ ϕy v3 (1 v (1 v ) y ) y + ψψy v ) y + Rθ v3 ϕ2y + λ ϕ2yy v6 = ψ2 y v +R ζyϕy v2 − ψψyV CD y v2 + ψϕyU CD y v2 + (R v − R V CD )ϕy v ΘCD y − (Rθ v2 − RΘCD (V CD)2 )ϕy v V CD y + UCD yy ϕϕy v2V CD + V CD y ψyϕy v3 − UCD y V CD y (v + V CD)ϕϕy v3(V CD)2 + λ (5ϕ2yϕyy v7 − 6ϕ4y v8 − V CD yy ϕyy v6 + 2ϕ2yV CD yy v7 + 8ϕyϕyyV CD y v7 + 2ϕyV CD y V CD yy v7 + 3ϕyy(V CD y )2 v7 − 18ϕ3yV CD y v8 − 18ϕ2y(V CD y )2 v8 − 6ϕy(V CD y )3 v8 ) +R1 ϕy v . (3.15) Here we also use that(1 v (1 v (1 v ) y ) y ) y ϕy v2 = (ϕy v3 (1 v (1 v ) y ) y ) y − 1 v (1 v (1 v ) y ) y (ϕy v2 ) y EJDE-2025/74 SHORT ZERO-VISCOSITY-CAPILLARITY LIMIT 9 = (ϕy v3 (1 v (1 v ) y ) y ) y + (vy v3 ) y (ϕyy v3 − 2ϕyvy v4 ) = (ϕy v3 (1 v (1 v ) y ) y ) y + ϕ2yy v6 + V CD yy ϕyy v6 − 5ϕ2yϕyy v7 − 2ϕ2yV CD yy v7 − 8ϕyϕyyV CD y v7 − 2ϕyV CD y V CD yy v7 − 3ϕyy(V CD y )2 v7 + 6ϕ4y v8 + 18ϕ3yV CD y v8 + 18ϕ2y(V CD y )2 v8 + 6ϕy(V CD y )3 v8 . Then integrating (3.15) with respect to τ and y over [τ0, τ ]×R (τ ≤ τ2) and using (1.3) and (3.1) yield ∥ϕy(τ)∥2 + ∫ τ τ0 (∥ϕy∥2 + ∥ϕyy∥2)dτ ≤ C ( ∥ψ(τ)∥2 + ∫ τ τ0 ∥ψy∥2dτ + 5∑ i=1 ∫ τ τ0 ∫ R Iidydτ ) . (3.16) Here we used the inequality∫ R (ψ ϕy v )(τ) dy ≤ 1 2 ∫ R ϕ2y(τ) dy + C ∫ R ψ2(τ) dy, and Ii(i = 1, . . . , 5) are given by I1 = |ζyϕy|, I2 = ϕ4y + ϕ2y|ϕyy|, I3 = |V CD yy ϕyy|+ |V CD y V CD yy ϕy|+ |(V CD y )2ϕyy|+ |(V CD y )3ϕy|+ |R1ϕy|, I4 = |V CD y ψψy|+ |UCD y ψϕy|+ |ΘCD y ϕϕy|+ |V CD y (ζ + ϕ)ϕy|+ |UCD yy ϕϕy|+ |UCD y V CD y ϕϕy|, I5 = |V CD y ψyϕy|+ |V CD yy ϕ2y|+ |V CD y ϕyϕyy|+ |(V CD y )2ϕ2y|+ |V CD y ϕ3y|. Now we estimate each term on the right-hand side of (3.16). First, using Hölder inequality and Young inequality, it is easy to obtain∫ τ τ0 ∫ R I1dydτ ≤ 1 8 ∫ τ τ0 ∥ϕy∥2 dτ + C ∫ τ τ0 ∥ζy∥2 dτ. (3.17) By Hölder inequality, Sobolev inequality, Young inequality and (2.4), it holds that∫ τ τ0 ∫ R I2dydτ ≤ C ∫ τ τ0 ∥ϕy∥2L∞∥ϕy∥2 dτ + C ∫ τ τ0 ∥ϕy∥L∞∥ϕy∥∥ϕyy∥dτ ≤ C(η1 + η21) ∫ τ τ0 ∥ϕy∥2 dτ + Cη1 ∫ τ τ0 ∥ϕyy∥2 dτ. (3.18) Moreover, as (3.6) and (3.8), we have∫ τ τ0 ∫ R I3dydτ ≤ 1 8 ∫ τ τ0 ∥ϕyy∥2 dτ + ϵ ∫ τ τ0 ∥ϕy∥2 dτ + Cϵ1/2, (3.19) and ∫ τ τ0 ∫ R I4dydτ ≤ C ( ϵ1/2 + ϵ+ ϵ3/2 ) ∫ τ τ0 (∥ϕ∥2 + ∥ϕy∥2) dτ + C ( ϵ1/2 + ϵ ) ∫ τ τ0 ∥ψ∥2 dτ + Cϵ1/2 ∫ τ τ0 (∥ζ∥2 + ∥ψy∥2) dτ. (3.20) Finally, similar to (3.8) and (3.12), one obtains∫ τ τ0 ∫ R I5dydτ ≤ Cϵ1/2 ∫ τ τ0 ∥ψy∥2 dτ + C ( ϵ1/2 + ϵ+ ϵ1/2η1 ) ∫ τ τ0 ∥ϕy∥2 ,dτ + Cϵ1/2 ∫ τ τ0 ∥ϕyy∥2 dτ. (3.21) 10 J. CHEN, Y. LI, R. YIN EJDE-2025/74 Then substituting estimates (3.17)-(3.21) into (3.16) and noting that ϵ and η1 are suitably small, we have ∥ϕy(τ)∥2 + ∫ τ τ0 (∥ϕy∥2 + ∥ϕyy∥2)dτ ≤ C ( ∥ψ(τ)∥2 + ∫ τ τ0 (∥ψy∥2 + ∥ζy∥2)dτ + (ϵ1/2 + ϵ+ ϵ3/2) ∫ τ τ0 ∥ϕ∥2 dτ + ( ϵ1/2 + ϵ ) ∫ τ τ0 ∥ψ∥2 dτ + ϵ1/2 ∫ τ τ0 ∥ζ∥2 dτ + ϵ1/2 ) , which together with (3.14) and the small behavior of ϵ and η1 yields ∥(ϕ, ψ, ζ, ϕy)(τ)∥2 + ∫ τ τ0 ∥(ϕy, ψy, ζy, ϕyy)∥2 dτ ≤ C ( ϵ1/2 + ϵ+ ϵ3/2 + ϵ2 ) ∫ τ τ0 ∥(ϕ, ζ)∥2 dτ + C ( ϵ1/2 + ϵ ) ∫ τ τ0 ∥ψ∥2 dτ + C ( ϵ1/2 + ϵ3/2 ) . (3.22) Then we can conclude from (3.22) by using the classical Gronwall inequality for τ ∈ [τ0, τ2] and the smallness of ϵ, ∥(ϕ, ψ, ζ, ϕy)(τ)∥2 + ∫ τ τ0 ∥(ϕy, ψy, ζy, ϕyy)∥2 dτ ≤ Cϵ1/2, which is (3.4) in Lemma 3.1. This completes the proof. □ Next, we derive the derivative estimate. For this, let us multiply (1.13)2 by −ψyy and ∂y(1.13)3 by ζy ΘCD . We have(1 2 ψ2 y + RΘCD 2(V CD)2 ϕ2y + λ 2v5 ϕ2yy ) τ + ψ2 yy v + (UCD yy ψy v − ψτψy − ( PCD vy ϕ + PCD θy ζ ) ψy − UCD y V CD y ψy v2 − UCD yy ψy V CD + UCD y V CD y ψy (V CD)2 + λ (ψyy v2 ( 1 v ( 1 v )y)y + ψyyV CD yy v5 − 3ψyyv 2 y v6 + 10V CD y V CD yy ψy v6 − 15(V CD y )3ψy v7 − V CD yyy ψy v5 )) y = (Rθ v − RΘCD V CD + RΘCD (V CD)2 ϕ− R V CD ζ ) y ψyy + (( RΘCD (V CD)2 ) y ϕ− ( R V CD ) y ζ ) y ψy + 1 2 ( RΘCD (V CD)2 ) τ ϕ2y + R V CD ζyψyy + ψyϕyψyy v2 + ψyψyyV CD y v2 + ϕyψyyU CD y v2 + (UCD yy v − UCD y V CD y v2 ) y ψy − 5λ 2v6 ϕ2yy(ψy + UCD y ) − λ (5(ϕyϕyy + 2ϕyV CD yy + ϕyyV CD y ) v6 − 15(ϕ3y + 3ϕ2yV CD y + 3ϕy(V CD y )2) v7 ) ψyy + λ (10V CD y V CD yy v6 − 15(V CD y )3 v7 − V CD yyy v5 ) y ψy − (UCD yy V CD − UCD y V CD y (V CD)2 ) y ψy +R1ψyy, (3.23) and ( ζ2y 2ΘCD ) τ + ν vΘCD ζ2yy + ( Rθ vΘCD ψyζy − R v ψyζy − νζy ΘCD ( θy v )y + ν(ΘCD yy v −ΘCD y vy) v2ΘCD ζy − u2yζy vΘCD + (UCD y )2ζy vΘCD − λζyuy ΘCD (5v2y 2v6 − vyy v5 ) + λζyU CD y ΘCD (5(V CD y )2 2v6 − V CD yy v5 ) +R2 ζy ΘCD ) y = 1 2 ( 1 ΘCD ) τ ζ2y + ( 1 ΘCD ) y ψyζy (Rθ v − RΘCD V CD ) + 1 ΘCD ψyζyy (Rθ v − RΘCD V CD ) EJDE-2025/74 SHORT ZERO-VISCOSITY-CAPILLARITY LIMIT 11 − 1 ΘCD ψyζy (RΘCD V CD ) y − ζyU CD y ΘCD (Rθ v − RΘCD V CD ) y − (Rθ v − RΘCD V CD )ζyUCD yy ΘCD + ν ΘCD ζyy ζyϕy + ζyV CD y + ϕyΘ CD y v2 + ( ν 1 ΘCD ΘCD yy v −ΘCD y V CD y v2 ) y ζy − ν ( 1 ΘCD ) y ζy (ζyyv − ζyϕy)− (ζyV CD y + ϕyΘ CD y ) + (ΘCD yy v −ΘCD y V CD y ) v2 + ν ( 1 ΘCD ) y ζy ΘCD yy V CD −ΘCD y V CD y (V CD)2 − ( ν 1 ΘCD ΘCD yy V CD −ΘCD y V CD y (V CD)2 ) y ζy − (ψy + UCD y )2 v ( 1 ΘCD ) y ζy + (UCD y )2 V CD ( 1 ΘCD ) y ζy − ψ2 y + 2ψyU CD y vΘCD ζyy − λ(ψy + UCD y ) (5(ϕy + V CD y )2 2v6 − ϕyy + V CD yy v5 )( 1 ΘCD ) y ζy − ( (UCD y )2 V CDΘCD ) y ζy − λζyyψy ΘCD (5(ϕy + V CD y )2 2v6 − ϕyy + V CD yy v5 ) + λ ((5(V CD y )2 2v6 − V CD yy v5 )UCD y ΘCD ) y ζy − R V CD ψyyζy + ( (UCD y )2 vΘCD ) y ζy − λζyyU CD y ΘCD (5(ϕ2y + 2ϕyV CD y ) 2v6 − ϕyy v5 ) +R2 ( ζy ΘCD ) y . (3.24) Lemma 3.2. Suppose that the assumptions in Proposition 2.1 hold. Then it holds that sup τ0≤τ≤τ2 ∥(ϕy, ψy, ζy, ϕyy)(τ)∥2 + ∫ τ2 τ0 ∥(ψyy, ζyy)∥2 dτ ≤ C ( ϵ1/2 + ϵ ) ∫ τ2 τ0 ∥ϕyy∥2 dτ + C ( η21 + ϵ 1 4 + ϵ ) ∫ τ2 τ0 ∥ϕyyy∥2 dτ + Cϵ 2 3 . (3.25) Proof. Taking a suitable linear combination of (3.23)-(3.24) and integrating the resultant equation with respect to τ and y over [τ0, τ ]× R (τ ≤ τ2), we obtain ∥(ϕy, ψy, ζy, ϕyy)(τ)∥2 + ∫ τ τ0 ∥(ψyy, ζyy)∥2 dτ ≤ C 6∑ i=1 ∫ τ τ0 ∫ R Ji dydτ, (3.26) where J1 = |ϕϕyψyy|+ |ζζyψyy|+ |ζψyζyy|+ |ϕψyζyy|+ |ζyϕyζyy|+ |ϕyψyψyy| + |ψ2 yζyy|+ |ψyϕyyζyy|+ |ϕ3yψyy|+ |ψyϕ 2 yζyy|, J2 = |ϕyψy(Θ CD y + V CD y )|+ |ζyψy(V CD y +ΘCD y )|+ |ϕ2yUCD y |+ |ζ2yUCD y | + |ζyϕyUCD y |+ |ϕyψy(U CD y V CD y + UCD yy )|+ |ζ2yΘCD y V CD y | + |ζyϕy((ΘCD y )2 +ΘCD yy +ΘCD y V CD y + (UCD y )2)|+ |ψyζyU CD y ΘCD y | + |ϕyψy(V CD y V CD yy + (V CD y )3 + V CD yyy )|+ |ψyζyΘ CD y ((V CD y )2 + V CD yy )| + |ϕyζy(UCD y V CD y ΘCD y + UCD y (V CD y )2 + UCD y V CD yy )|, J3 = |ϕψy(V CD y ΘCD y +ΘCD yy + (V CD y )2 + V CD yy )|+ |ζψy((V CD y )2 + V CD yy )| + |(ϕ+ ζ)ζyU CD yy |+ |ϕψy(V CD y UCD yy + UCD yyy + (V CD y )2UCD y + V CD yy UCD y )| + |ϕζy(ΘCD y (ΘCD yy + V CD yy + (V CD y )2 + (UCD y )2) + (ΘCD y )2V CD y +ΘCD yyy +ΘCD yy V CD y + V CD y (UCD y )2 + UCD y UCD yy )|, J4 = |ϕyψyyU CD y |+ |ϕyψyy(V CD yy + (V CD y )2)|+ |ζyζyy(ΘCD y + V CD y )| + |ϕyζyyΘCD y |+ |ψyζyyU CD y |+ |ϕyyζyUCD y ΘCD y |+ |ζyyψy((V CD y )2 + V CD yy )| + |ϕyζyyUCD y V CD y |+ |ζyϕyyyV CD y |+ |ϕyyζyyUCD y |, 12 J. CHEN, Y. LI, R. YIN EJDE-2025/74 J5 = |ψy((V CD y )2V CD yy + (V CD yy )2 + V CD y V CD yyy + (V CD y )4 + V CD yyyy)|+ |R1ψyy| + |ζy(UCD y ((V CD y )2ΘCD y + V CD yy ΘCD y + (V CD y )3 + V CD y V CD yy + V CD yyy ) + UCD yy (V CD y )2 + UCD yy V CD yy )|+ |R2ζyy|+ |R2Θ CD y ζy|, J6 = |ϕ2yψyyV CD y |+ |ζ2yϕyΘCD y |+ |ψ2 yζyΘ CD y |+ |ϕ2yζyyUCD y |+ |ϕ2yζyUCD y ΘCD y | + |ϕ2yψyζyΘ CD y |+ |ψyϕyyζyΘ CD y |+ |ψyϕyζyV CD y ΘCD y |+ |ζyyψyϕyV CD y | + |(ζy + ϕy)ψyζyΘ CD y |. Now let us estimate each term on the right-hand side of (3.26). First, using Young inequality, Sobolev inequality (2.4) and (3.4), one obtains∫ τ τ0 ∫ R (|ζψyζyy|+ |ζyϕyζyy|) dydτ ≤ 1 24 ∫ τ τ0 ∫ R ζ2yy dydτ + C ∫ τ τ0 (∥ζ∥2L∞∥ψy∥2 + ∥ϕy∥2L∞∥ζy∥2) dτ ≤ 1 24 ∫ τ τ0 ∫ R ζ2yy dydτ + C ∫ τ τ0 (∥ζ∥∥ζy∥∥ψy∥2 + ∥ϕy∥∥ϕyy∥∥ζy∥2) dτ ≤ 1 24 ∫ τ τ0 ∫ R ζ2yy dydτ + C sup τ0≤τ≤τ ∥ζ∥∥ζy∥ ∫ τ τ0 ∥ψy∥2 dτ + C sup τ0≤τ≤τ ∥ϕy∥∥ϕyy∥ ∫ τ τ0 ∥ζy∥2 dτ ≤ 1 24 ∫ τ τ0 ∫ R ζ2yy dydτ + 1 16 sup τ0≤τ≤τ ∥ζy∥2 + C sup τ0≤τ≤τ ∥ζ∥2 ( ∫ τ τ0 ∥ψy∥2 dτ )2 + 1 48 sup τ0≤τ≤τ ∥ϕyy∥2 + C sup τ0≤τ≤τ ∥ϕy∥2 ( ∫ τ τ0 ∥ζy∥2 dτ )2 ≤ 1 24 ∫ τ τ0 ∫ R ζ2yy dydτ + 1 16 sup τ0≤τ≤τ ∥ζy∥2 + 1 48 sup τ0≤τ≤τ ∥ϕyy∥2 + Cϵ3/2, (3.27) and ∫ τ τ0 ∫ R (|ψ2 yζyy|+ |ψyϕyyζyy|) dydτ ≤ 1 24 ∫ τ τ0 ∫ R ζ2yy dydτ + C ∫ τ τ0 (∥ψy∥2L∞ + ∥ϕyy∥2L∞)∥ψy∥2 dτ ≤ 1 24 ∫ τ τ0 ∥ζyy∥2 dτ + C ∫ τ τ0 (∥ψy∥∥ψyy∥+ ∥ϕyy∥∥ϕyyy∥)∥ψy∥2 dτ ≤ 1 24 ∫ τ τ0 ∥ζyy∥2 dτ + 1 88 ∫ τ τ0 ∥ψyy∥2 dτ + C ∫ τ τ0 ∥ψy∥2∥ψy∥4 dτ + C ∫ τ τ0 (∥ϕyy∥2 + ∥ϕyyy∥2)∥ψy∥2 dτ ≤ 1 24 ∫ τ τ0 ∥ζyy∥2 dτ + 1 88 ∫ τ τ0 ∥ψyy∥2 dτ + C sup τ0≤τ≤τ ∥ψy∥2η21 ∫ τ τ0 ∥ψy∥2 dτ + C sup τ0≤τ≤τ ∥ϕyy∥2 ∫ τ τ0 ∥ψy∥2 dτ + C sup τ0≤τ≤τ ∥ψy∥2 ∫ τ τ0 ∥ϕyyy∥2 dτ ≤ 1 24 ∫ τ τ0 ∥ζyy∥2 dτ + 1 88 ∫ τ τ0 ∥ψyy∥2 dτ + Cη21ϵ 1/2 sup τ0≤τ≤τ ∥ψy∥2 + Cϵ1/2 sup τ0≤τ≤τ ∥ϕyy∥2 + Cη21 ∫ τ τ0 ∥ϕyyy∥2 dτ. EJDE-2025/74 SHORT ZERO-VISCOSITY-CAPILLARITY LIMIT 13 In the same way, we can deal with the remainder terms in ∫ τ τ0 ∫ R J1 dydτ . Then we have∫ τ τ0 ∫ R J1 dydτ ≤ 1 8 ∫ τ τ0 (∥ψyy∥2 + ∥ζyy∥2) dτ + Cη21 ∫ τ τ0 ∥ϕyyy∥2 dτ + (1 8 + Cη21ϵ 1/2 ) sup τ0≤τ≤τ ∥ϕy∥2 + 1 8 sup τ0≤τ≤τ ∥ζy∥2 + (1 8 + Cϵ1/2 ) sup τ0≤τ≤τ ∥ϕyy∥2 + Cη21ϵ 1/2 sup τ0≤τ≤τ ∥ψy∥2 + Cϵ3/2. (3.28) Next, employing (3.4) and using a similar process to (3.8), we have∫ τ τ0 ∫ R J2 dydτ ≤ C ( ϵ+ ϵ3/2 + ϵ2 + ϵ5/2 ) . (3.29) By (2.3), Hölder inequality, Sobolev inequality, Young inequality and (3.4), we obtain∫ τ τ0 ∫ R |V CD y ΘCD y ϕψy|dydτ ≤ C ∫ τ τ0 ∫ R |ϵe− 2c0y2 τ ϕψy|dydτ ≤ C ∫ τ τ0 ϵ∥ϕ∥∥ψy∥L4τ1/8 dτ ≤ C ∫ τ τ0 ϵ∥ϕ∥∥ψy∥1/4∥ψyy∥3/4τ1/8 dτ ≤ 1 24 ∫ τ τ0 ∥ψyy∥2 dτ + C ∫ τ τ0 ∥ϕ∥8/5∥ψy∥2/5ϵ8/5τ1/5 dτ ≤ 1 24 ∫ τ τ0 ∥ψyy∥2 dτ + C ∫ τ τ0 ∥ϕ∥2ϵ11/8τ5/24 dτ + C ∫ τ τ0 ∥ψy∥2ϵ5/2τ1/6 dτ ≤ 1 24 ∫ τ τ0 ∥ψyy∥2 dτ + C sup τ0≤τ≤τ ∥ϕ∥2ϵ 11 8 ϵ−29/24 + C sup τ0≤τ≤τ ∥ψy∥2ϵ5/2ϵ−7/6 ≤ 1 24 ∫ τ τ0 ∥ψyy∥2 dτ + Cϵ1/6 sup τ0≤τ≤τ ∥ϕ∥2 + Cϵ4/3 sup τ0≤τ≤τ ∥ψy∥2 ≤ 1 24 ∫ τ τ0 ∥ψyy∥2 dτ + Cϵ4/3 sup τ0≤τ≤τ ∥ψy∥2 + Cϵ2/3. We can similarly estimate the other terms in ∫ τ τ0 ∫ R J3 dydτ to obtain∫ τ τ0 ∫ R J3 dydτ ≤ 1 8 ∫ τ τ0 (∥ψyy∥2 + ∥ζyy∥2) dτ + Cϵ ∫ τ τ0 ∥ϕyy∥2 dτ + Cϵ17/6 sup τ0≤τ≤τ ∥ζy∥2 + C ( ϵ4/3 + ϵ13/3 ) sup τ0≤τ≤τ ∥ψy∥2 + Cϵ17/6 sup τ0≤τ≤τ ∥ϕy∥2 + C ( ϵ2/3 + ϵ 31 24 + ϵ23/12 + ϵ61/24 ) . (3.30) Moreover, utilizing (2.3), Hölder inequality, Sobolev inequality and Young inequality, one obtains∫ τ τ0 ∫ R |UCD y ϕyψyy|dydτ ≤ C ∫ τ τ0 ∫ R |ϵe−c0y 2/τϕyψyy|dydτ ≤ C ∫ τ τ0 ϵ∥ψyy∥∥ϕy∥L4τ1/8 dτ ≤ C ∫ τ τ0 ϵ∥ψyy∥∥ϕy∥1/4∥ϕyy∥3/4τ1/8 dτ ≤ 1 64 ∫ τ τ0 ∥ψyy∥2 dτ + Cϵ2 ∫ τ τ0 ∥ϕy∥1/2∥ϕyy∥3/2τ1/4 dτ 14 J. CHEN, Y. LI, R. YIN EJDE-2025/74 ≤ 1 64 ∫ τ τ0 ∥ψyy∥2 dτ + Cϵ ∫ τ τ0 ∥ϕyy∥2 dτ + C ∫ τ τ0 ϵ5∥ϕy∥2τ dτ ≤ 1 64 ∫ τ τ0 ∥ψyy∥2 dτ + Cϵ ∫ τ τ0 ∥ϕyy∥2 dτ + Cϵ3 sup τ0≤τ≤τ ∥ϕy∥2. Similarly, we estimate the other terms in ∫ τ τ0 ∫ R J4 dydτ to obtain∫ τ τ0 ∫ R J4 dydτ ≤ 1 8 ∫ τ τ0 (∥ψyy∥2 + ∥ζyy∥2) dτ + C(ϵ1/2 + ϵ) ∫ τ τ0 ∥ϕyy∥2 dτ + C(ϵ 1 4 + ϵ) ∫ τ τ0 ∥ϕyyy∥2 dτ + C ( ϵ1/2 + ϵ3 + ϵ7 ) sup τ0≤τ≤τ ∥ϕy∥2 + Cϵ6 sup τ0≤τ≤τ ∥ψy∥2 + Cϵ3 sup τ0≤τ≤τ ∥ϕyy∥2 + C ( ϵ+ ϵ2 + ϵ6 ) sup τ0≤τ≤τ ∥ζy∥2. (3.31) With (2.3), Hölder inequality and Young inequality in hand, we have∫ τ τ0 ∫ R (|(V CD y )2V CD yy ψy|+ |R1ψyy|) dydτ ≤ C ∫ τ τ0 ∫ R (|ϵ2e− 3c0y2 τ ψy|+ |ϵ3/2e−c0y 2/τψyy|) dydτ ≤ C ∫ τ τ0 ϵ2∥ψy∥τ1/4 dτ + 1 8 ∫ τ τ0 ∥ψyy∥2 dτ + Cϵ3 ∫ τ τ0 ∫ R e− 2c0y2 τ dydτ ≤ Cϵ2 sup τ0≤τ≤τ ∥ψy∥ ∫ τ τ0 τ1/4 dτ + 1 8 ∫ τ τ0 ∥ψyy∥2 dτ + Cϵ3 ∫ τ τ0 τ1/2 dτ ≤ Cϵ3/4 sup τ0≤τ≤τ ∥ψy∥+ 1 8 ∫ τ τ0 ∥ψyy∥2 dτ + Cϵ 3/2 ≤ 1 8 sup τ0≤τ≤τ ∥ψy∥2 + 1 8 ∫ τ τ0 ∥ψyy∥2 dτ + Cϵ3/2. Hence, we obtain∫ τ τ0 ∫ R J5 dydτ ≤ 1 8 ∫ τ τ0 (∥ψyy∥2 + ∥ζyy∥2) dτ + 1 8 sup τ0≤τ≤τ ∥ψy∥2 + 1 8 sup τ0≤τ≤τ ∥ζy∥2 + C(ϵ3/2 + ϵ5/2). (3.32) By (2.3), Hölder inequality, Sobolev inequality, Young inequality and (3.4), we have∫ τ τ0 ∫ R |UCD y ϕ2yζyy|dydτ ≤ C ∫ τ τ0 ∫ R ∣∣ϵe−c0y 2/τϕ2yζyy ∣∣dydτ ≤ Cϵ ∫ τ τ0 ∥ϕy∥2L∞∥ζyy∥τ1/4 dτ ≤ Cϵ ∫ τ τ0 ∥ϕy∥∥ϕyy∥∥ζyy∥τ1/4 dτ ≤ ϵ1/2 ∫ τ τ0 ∥ζyy∥2 dτ + Cϵ3/2 ∫ τ τ0 ∥ϕy∥2∥ϕyy∥2τ1/2 dτ ≤ ϵ1/2 ∫ τ τ0 ∥ζyy∥2 dτ + C sup τ0≤τ≤τ ∥ϕy∥2∥ϕyy∥2 ≤ ϵ1/2 ∫ τ τ0 ∥ζyy∥2 dτ + Cϵ1/2 sup τ0≤τ≤τ ∥ϕyy∥2. (3.33) EJDE-2025/74 SHORT ZERO-VISCOSITY-CAPILLARITY LIMIT 15 Noting e− nc0y2 τ ≤ 1, for n ∈ N+, similar to (3.28) and (3.33), one obtains∫ τ τ0 ∫ R J6 dydτ ≤ C ( ϵ1/2 + ϵ ) ∫ τ τ0 ∥ϕyy∥2 dτ + Cϵ1/2 ∫ τ τ0 ∥ζyy∥2 dτ + C ( ϵ+ ϵ2 ) + (1 8 + Cϵ1/2 ) ∫ τ τ0 ∥ψyy∥2 dτ + C ( ϵ1/2 + ϵ+ ϵ3/2 ) sup τ0≤τ≤τ ∥ϕyy∥2 + C ( ϵ1/2 + ϵ1/4η21 + ϵ ) sup τ0≤τ≤τ ∥ζy∥2 + C ( ϵ1/2 + ϵ+ ϵ3/2 ) sup τ0≤τ≤τ ∥ψy∥2. (3.34) Substituting these estimates (3.28)-(3.32) and (3.34) into (3.26) and noting that ϵ and η1 are suitably small that we can prove (3.25) for τ ∈ [τ0, τ2] in Lemma 3.2. This completes the proof. □ Finally, we deal with the estimations for ∫ τ τ0 ∥ϕyy∥2 dτ and ∫ τ τ0 ∥ϕyyy∥2 dτ . To this end, we multiply ∂y (1.13)2 by ϕyy v to have (ϕ2yy 2v2 − ψyϕyy v ) τ + λ v6 ϕ2yyy − 1 v ψ2 yy + Rθ v3 ϕ2yy − R v2 ζyyϕyy + (UCD yyy ϕy v2 − 2UCD yy V CD y ϕy v3 − UCD y V CD yy ϕy v3 + 2UCD y (V CD y )2ϕy v4 − UCD yyy ϕy vV CD + 2UCD yy V CD y ϕy v(V CD)2 + UCD y V CD yy ϕy v(V CD)2 − 2UCD y (V CD y )2ϕy v(V CD)3 + λ (ϕyy v2 ( 1 v ( 1 v ( 1 v )y)y)y + V CD yyy ϕyy v6 − 10V CD y V CD yy ϕyy v7 + 15(V CD y )3ϕyy v8 − V CD y V CD yyy ϕy v7 + 10(V CD y )2V CD yy ϕy v8 − 15(V CD y )4ϕy v9 ) + ψyψyy v − (Rθ v − RΘCD V CD ) y ϕyy v − Rθϕyϕyy v3 + Rζyϕyy v2 −R1 ϕyy v ) y = 1 2 ( 1 v2 ) τ ϕ2yy + (UCD yyy v2 − 2UCD yy V CD y v3 − UCD y V CD yy v3 + 2UCD y (V CD y )2 v4 ) y ϕy − ( UCD yyy vV CD − 2UCD yy V CD y v(V CD)2 − UCD y V CD yy v(V CD)2 + 2UCD y (V CD y )2 v(V CD)3 ) y ϕy + 2ϕyy(ϕy(ψyy + UCD yy ) + ψyyV CD y ) v3 + (ψy + UCD y )ϕ2yy + ψyϕyyV CD yy v3 − 2ψy(ϕy + V CD y )2ϕyy + 2UCD y (ϕ2y + 2ϕyV CD y )ϕyy v4 + λ (V CD yyy v6 − 10V CD y V CD yy v7 + 15(V CD y )3 v8 ) y ϕyy − λ (V CD y V CD yyy v7 − 10(V CD y )2V CD yy v8 + 15(V CD y )4 v9 ) y ϕy + λ v (10(V CD y + ϕy)ϕyy + 10ϕyV CD yy v6 − 15(ϕ3y + 3ϕ2yV CD y + 3ϕy(V CD y )2) v7 ) ϕyyy + λ v2 (ϕyyy + V CD yyy v5 − 10(ϕy + V CD y )(ϕyy + V CD yy ) v6 + 15(ϕy + V CD y )3 v7 ) ϕyϕyy − (1 v ) τ ψyϕyy + (1 v ) y ψyψyy + λV CD y v2 (ϕyyy v5 − 10(ϕyϕyy + ϕyV CD yy + ϕyy) v6 16 J. CHEN, Y. LI, R. YIN EJDE-2025/74 + 15(ϕ3y + 3ϕ2yV CD y + 3ϕy(V CD y )2) v7 ) ϕyy + R v2V CD ϕΘCD y ϕyyy − (Rθ v − RΘCD V CD ) y (1 v ) y ϕyy − ((Rθ v3 ) y ϕy − (R v2 ) y ζy ) ϕyy + R v3 ζϕyyyV CD y − RΘCD(v + V CD) v3(V CD)2 ϕϕyyyV CD y −R1 (ϕyy v ) y . (3.35) Lemma 3.3. Suppose that the assumptions in Proposition 2.1 hold. Then it holds that sup τ0≤τ≤τ2 ∥ϕyy(τ)∥2 + ∫ τ2 τ0 ∥(ϕyy, ϕyyy)∥2 dτ ≤ C sup τ0≤τ≤τ2 ∥(ϕy, ψy, ζy)(τ)∥2 + C ∫ τ2 τ0 ∥(ψyy, ζyy)∥2 dτ + Cϵ. (3.36) Proof. Integrating (3.35) with respect to τ and y over [τ0, τ ]× R (τ ≤ τ2), we have ∥ϕyy(τ)∥2 + ∫ τ τ0 ∥(ϕyy, ϕyyy)∥2 dτ ≤ C ( ∥ψy(τ)∥2 + ∫ τ τ0 ∥(ψyy, ζyy)∥2 dτ + 7∑ i=1 ∫ τ τ0 ∫ R Ki dydτ ) , (3.37) where K1 = |ϕyϕyyψyy|+ |ϕyϕyyϕyyy|+ |ϕ2yϕyy|+ |ϕyζyϕyy|+ |ϕyψyψyy| + |ϕ2yyψy|+ |ψ2 yϕyy|+ |ϕ3yϕyyy|+ |ψyϕ 2 yϕyy|+ |ϕ2yϕ2yy|+ |ϕ4yϕyy|, K2 = |ϕ2y(UCD yyy + UCD yy V CD y + UCD y V CD yy + UCD y (V CD y )2)| + |ϕ2y(V CD y V CD yyy + (V CD y )2V CD yy + (V CD y )4)|, K3 = |ϕϕy(V CD y (UCD yyy + UCD y V CD yy + UCD y (V CD y )2) + (V CD y )2UCD yy + UCD yyyy + UCD yy V CD yy + UCD y V CD yyy )|, K4 = |ψyψyyV CD y |+ |ψyϕyy(V CD yy + (V CD y )2)|+ |ϕyϕyy(UCD y V CD y + UCD yy )| + |ϕyϕyy(V CD yyy + V CD y V CD yy + (V CD y )3)|+ |ϕyϕyyy(V CD yy + (V CD y )2)| + |ϕyyϕyyyV CD y |+ |ψyϕyyU CD y |+ |ϕyϕyy(V CD y +ΘCD y )| + |ζyϕyyV CD y |+ |ϕyyψyyV CD y |+ |ϕ2yyUCD y |+ |ϕ2yy(V CD y )2| + |ϕyϕyyy(V CD y +ΘCD y )|+ |R1ϕyϕyy|, K5 = |ϕyy(V CD y V CD yyy + (V CD y )2V CD yy + (V CD y )4 + V CD yyyy + (V CD yy )2)| + |ϕy((V CD y )2V CD yyy + V CD y V CD yyyy + V CD yy V CD yyy + (V CD y )3V CD yy + V CD y (V CD yy )2 + (V CD y )5)|+ |R1ϕyyy|+ |R1V CD y ϕyy|, K6 = |ϕ2yϕyyyV CD y |+ |ϕyϕ2yyV CD y |+ |ϕ2yϕyy(V CD yy + (V CD y )2)| + |ϕ2yϕyyUCD y |+ |ψyϕyϕyyV CD y |+ |ϕ3yϕyyV CD y |, K7 = |ϕϕ2y(UCD yyy + UCD yy V CD y + UCD y V CD yy + UCD y (V CD y )2)|. Firstly, similar to (3.28)-(3.32) and (3.34), one obtains∫ τ τ0 ∫ R K1 dydτ ≤ 1 8 ∫ τ τ0 (∥ϕyy∥2 + ∥ψyy∥2 + ∥ϕyyy∥2) dτ + (1 8 + Cη41ϵ 1/2 ) sup τ0≤τ≤τ ∥ϕyy∥2 + Cη21ϵ 1/2 ( sup τ0≤τ≤τ ∥ϕy∥2 + sup τ0≤τ≤τ ∥ψy∥2 ) + Cϵ3/2, (3.38) EJDE-2025/74 SHORT ZERO-VISCOSITY-CAPILLARITY LIMIT 17∫ τ τ0 ∫ R K2 dydτ ≤ Cϵ5/2, (3.39)∫ τ τ0 ∫ R K3 dydτ ≤ 1 8 ∫ τ τ0 ∥ζyy∥2 dτ + C ( ϵ 17 6 + ϵ 35 6 ) sup τ0≤τ≤τ ∥ζy∥2 + C ( ϵ 31 24 + ϵ 61 24 ) , (3.40) ∫ τ τ0 ∫ R K4 dydτ ≤ 1 8 ∫ τ τ0 (∥ϕyy∥2 + ∥ψyy∥2 + ∥ζyy∥2 + ∥ϕyyy∥2) dτ + Cϵ2 sup τ0≤τ≤τ ∥ζy∥2 + C ( ϵ2 + ϵ6 + ϵ10 ) sup τ0≤τ≤τ ∥ϕy∥2 + C ( ϵ2 + ϵ6 ) ( sup τ0≤τ≤τ ∥ψy∥2 + sup τ0≤τ≤τ ∥ϕyy∥2), (3.41) ∫ τ τ0 ∫ R K5 dydτ ≤ 1 8 ∫ τ τ0 ∥ϕyyy∥2 dτ + 1 8 sup τ0≤τ≤τ ∥(ϕy, ϕyy)∥2 + C ( ϵ3/2 + ϵ5/2 ) , (3.42) ∫ τ τ0 ∫ R K6 dydτ ≤ C ( ϵ1/2 + ϵ+ ϵ1/2η1 ) ∫ τ τ0 ∥ϕyy∥2 dτ + Cϵ1/2 ∫ τ τ0 ∥ψyy∥2 dτ + Cϵ1/2 ∫ τ τ0 ∥ϕyyy∥2 dτ + C ( ϵ1/2 + ϵ ) sup τ0≤τ≤τ ∥ϕyy∥2 + C ( ϵ+ ϵ2 ) . (3.43) It follows from (2.3), Hölder inequality, Sobolev inequality, Young inequality and (3.4) that∫ τ τ0 ∫ R K7 dydτ ≤ C ∫ τ τ0 ∫ R ∣∣ϵ2(e−c0y 2/τ + e− 2c0y2 τ + e− 3c0y2 τ ) ϕϕ2y ∣∣dydτ ≤ Cϵ2 ∫ τ τ0 ∥ϕ∥τ1/4∥ϕy∥2L∞ dτ ≤ Cϵ2 ∫ τ τ0 ∥ϕ∥τ1/4∥ϕy∥∥ϕyy∥ dτ ≤ Cϵ2 ∫ τ τ0 ∥ϕyy∥2 dτ + Cϵ2 ∫ τ τ0 ∥ϕ∥2τ1/2∥ϕy∥2 dτ ≤ Cϵ2 ∫ τ τ0 ∥ϕyy∥2 dτ + Cϵ2 sup τ0≤τ≤τ ∥ϕ∥2 sup τ0≤τ≤τ ∥ϕy∥2ϵ− 3 2 ≤ Cϵ2 ∫ τ τ0 ∥ϕyy∥2 dτ + Cϵ3/2. (3.44) Substituting estimates (3.38)-(3.44) into (3.37) and noting that ϵ and η1 are suitably small, we can prove (3.36) for τ ∈ [τ0, τ2] in Lemma 3.3. This completes the proof. □ Acknowledgements. The research was supported in part by the National Natural Science Foun- dation of China (Grant No. 12171258). References [1] H. Cai, Z. Tan, Q.-J. Xu; Time periodic solutions of the non-isentropic compressible fluid models of Korteweg type, Kinetic and Related Models, 8(2015), 29-51. [2] F. Charve, B. Haspot; Existence of global strong solution and vanishing capillarity-viscosity limit in one dimension for the Korteweg system, SIMA J. Math. Anal., 45(2014), 469-494. [3] Z.-Z. Chen, L. He, H.-J. Zhao; Global smooth solutions to the nonisothermal compressible fluid models of Korteweg type with large initial data, Z. Angew. Math. Phys., 68(2017), 37 pp. [4] Z.-Z. Chen, M.-D. Sheng; Global stability of combination of a viscous contact wave with rarefaction waves for the compressible fluid models of Korteweg type, Nonlinearity, 32(2019), 395-444. [5] Z.-Z. Chen, Q.-H. Xiao; Nonlinear stability of viscous contact wave for the one-dimensional compressible fluid models of Korteweg type, Math. Meth. Appl. Sci., 36(2013), 2265-2279. 18 J. CHEN, Y. LI, R. YIN EJDE-2025/74 [6] Z.-Z. Chen, L.-J. Xiong, Y.-J. Meng; Convergence to the superposition of rarefaction waves and contact discontinuity for the 1-D compressible Navier-Stokes-Korteweg system, J. Math. Anal. Appl., 412(2014), 646- 663. [7] Z.-Z. Chen, H.-J. Zhao; Existence and nonlinear stability of stationary solutions to the full compressible Navier-Stokes-Korteweg system, J. Math. Pures Appl., 101(2014), 330-371. [8] J.-E. Dunn, J. Serrin; On the thermodynamics of interstital working, Arch. Rational Mech. Anal., 88(1985), 95-133. [9] B.-R. Gao, Y.-P. Li, R. Yin; Asymptotics toward rarefaction wave for an inflow problem of the full compressible Navier-Stokes-Korteweg equations, Prepint, 2023. [10] J. Goodman, Z. Xin; Viscous limits for piecewise snooth solutions to systems of conservation laws, Arch. Ration. Mech. Anal., 121(1992), 235-265. [11] B. Haspot; Existence of strong solutions for nonisothermal Korteweg system, Annales Mathématiques Blaise Pascal, 16(2009), 431-481. [12] H. Hattori, D. Li; The existence of global solutions to a fluid dynamic model for materials for Korteweg type, J. Partial Differ. Equ., 9(1996), 323-342. [13] M. Heida, J. Málek; On compressible Korteweg fluid-like materials, Internat. J. Engrg. Sci., 48(2010), 1313- 1324. [14] D. Hoff, T.-P. Liu; The inviscid limit for the Navier-Stokes equations of compressible, isentropic flow with shock data, Indiana Univ. Math. J., 38(1989), 861-915. [15] X.-F. Hou, H.-Y. Peng, C.-J. Zhu; Global well-posedness of the 3D non-isothermal compressible fluid model of Korteweg type, Nonlinear Anal.: Real World Applications, 43(2018), 18-53. [16] X.-F. Hou, L. Yao, C.-J. Zhu; Vanishing capillarity limit of the compressible non-estropic Navier-Stokes- Korteweg system to the Navier-Stokes equations, J. Math. Anal. Appl., 448(2017), 421-446. [17] D.-J. Korteweg; Sur la forme que prennent les équations des mouvement des fluids si l’on tient comple des forces capillaries par des variations de densité, Arch. Neerl. Sci. Exactes Nat. Ser. II, 6(1901), 1-24. [18] M. Kotschote; Strong well-posedness for a Korteweg type for the dynamics of a compressible non-isothermal fluid, J. Math. Fluid Mech., 12(2010), 473-483. [19] M. Kotschote; Dynamics of compressible non-isothermal fluids of non-Newtonian Korteweg type, SIAM J. Math. Anal., 44(2012), 74-101. [20] M. Kotschote; Existence and time-asymptotics of global strong solutions to dynamic Korteweg models, Indiana Univ. Math. J., 63(2014), 21-51. [21] P.-D. Lax; Hyperbolic systems of conservation laws, II, Comm. Pure Appl. Math., 10(1957), 537-566. [22] Y.-P. Li, Z. Luo; Zero-capillarity-viscosity limit to rarefaction waves for the one-dimensional compressible Navier-Stokes-Korteweg equations, Math. Meth. Appl. Sci., 39(2016), 5513-5528. [23] Y.-P. Li, P.-C. Zhu; Zero-viscosity-capillarity limit to rarefaction wave with vacuum for the compressible Navier-Stokes-Korteweg equations, J. Math. Phy., 61(2020), 111501. [24] Y.-P. Li, Q.-W. Wu; Stationary solutions to the one-dimensional full compressible Navier-Stokes-Korteweg equations in the half line, J. Differential Equations, 261(2023), 5949-5991. [25] S.-X. Ma; Zero dissipation limit to strong contact discontinuity for the 1-D compressible Navier-Stokes equa- tions, J. Differential Equations, 248(2010), 95-110. [26] Y.-J. Qian, R. Yin, Y.-P. Li; Asymptotic behavior of solutions to the full compressible Navier-Stokes-Korteweg equation in the half space, Appl. Math. Letters, 137(2023), 108499. [27] J.-D. Van der Waals; Thermodynamische Theorie der Kapillarität unter Voraussetzung stetiger Dichteänderung, Z. Phys. Chem., 13(1894), 657-725. [28] W.-J. Wang, L. Yao; Vanishing viscosity limit to rarefaction waves for the full compressible fluid models of Korteweg type, Comm. Pure Appl. Anal., 13(2004), 2331-2350. [29] R. Yin, Y.-P. Li; Zero-viscosity-capillarity limit to the planar rarefaction wave for the 2D compressible Navier- Stokes-Korteweg equations, Nonlinear Anal.: Real World Applications, 68(2022), 103685. [30] R. Yin, Y.-P. Li, Y.-J. Qian; Zero-viscosity-capillarity limit towards rarefaction wave for the full Navier- Stokes-Korteweg system of compressible fluids, Math. Methods App. Sci., 46(2023), 9485-9507. [31] X. Zhang, Z. Tan; Decay estimates of the non-isentropic compressible fluid models of Korteweg type in R3, Comm. Math. Sci., 12(2014), 1437-1456. Jiaxue Chen School of Mathematics and statistics, Nantong University, Nantong 226019, China Email address: jxchen2025@163.com Yeping Li School of Mathematics and statistics, Nantong University, Nantong 226019, China Email address: ypleemei@aliyun.com Rong Yin (corresponding author) School of Mathematics and statistics, Nantong University, Nantong 226019, China Email address: yin.r@ntu.edu.cn 1. Introduction 2. Reformulation of the Problem and Proof of Theorem 1.1 3. A priori estimate Acknowledgements References