In this article, on the basis of two-level discretizations and multiscale finite element method, two kinds of finite element algorithms for steady Navier-Stokes problem are presented and discussed. The main technique ...In this article, on the basis of two-level discretizations and multiscale finite element method, two kinds of finite element algorithms for steady Navier-Stokes problem are presented and discussed. The main technique is first to use a standard finite element discretization on a coarse mesh to approximate low frequencies, then to apply the simple and Newton scheme to linearize discretizations on a fine grid. At this process, multiscale finite element method as a stabilized method deals with the lowest equal-order finite element pairs not satisfying the inf-sup condition. Under the uniqueness condition, error analyses for both algorithms are given. Numerical results are reported to demonstrate the effectiveness of the simple and Newton scheme.展开更多
This paper is concerned with the global well-posedness of the solution to the compressible Navier-Stokes/Allen-Cahn system and its sharp interface limit in one-dimensional space.For the perturbations with small energy...This paper is concerned with the global well-posedness of the solution to the compressible Navier-Stokes/Allen-Cahn system and its sharp interface limit in one-dimensional space.For the perturbations with small energy but possibly large oscillations of rarefaction wave solutions near phase separation,and where the strength of the initial phase field could be arbitrarily large,we prove that the solution of the Cauchy problem exists for all time,and converges to the centered rarefaction wave solution of the corresponding standard two-phase Euler equation as the viscosity and the thickness of the interface tend to zero.The proof is mainly based on a scaling argument and a basic energy method.展开更多
This paper is concerned with the Navier-Stokes/Allen-Cahn system,which is used to model the dynamics of immiscible two-phase flows.We consider a 1D free boundary problem and assume that the viscosity coefficient depen...This paper is concerned with the Navier-Stokes/Allen-Cahn system,which is used to model the dynamics of immiscible two-phase flows.We consider a 1D free boundary problem and assume that the viscosity coefficient depends on the density in the form ofη(ρ)=ρ^(α).The existence of unique global H^(2m)-solutions(m∈N)to the free boundary problem is proven for when 0<α<1/4.Furthermore,we obtain the global C^(∞)-solutions if the initial data is smooth.展开更多
In this paper,we study the one-dimensional motion of viscous gas near a vacuum,with the gas connecting to a vacuum state with a jump in density.The interface behavior,the pointwise decay rates of the density function ...In this paper,we study the one-dimensional motion of viscous gas near a vacuum,with the gas connecting to a vacuum state with a jump in density.The interface behavior,the pointwise decay rates of the density function and the expanding rates of the interface are obtained with the viscosity coefficientμ(ρ)=ρ^(α)for any 0<α<1;this includes the timeweighted boundedness from below and above.The smoothness of the solution is discussed.Moreover,we construct a class of self-similar classical solutions which exhibit some interesting properties,such as optimal estimates.The present paper extends the results in[Luo T,Xin Z P,Yang T.SIAM J Math Anal,2000,31(6):1175-1191]to the jump boundary conditions case with density-dependent viscosity.展开更多
本论文对Navier-Stokes方程非阻尼极限进行了研究,即对带有阻尼项的Navier-Stokes方程解的极限行为进行研究。证明了在相同初值条件下,带有不同阻尼项的Navier-Stokes方程的解u均收敛到Navier-Stokes方程的解v。In this paper, the unda...本论文对Navier-Stokes方程非阻尼极限进行了研究,即对带有阻尼项的Navier-Stokes方程解的极限行为进行研究。证明了在相同初值条件下,带有不同阻尼项的Navier-Stokes方程的解u均收敛到Navier-Stokes方程的解v。In this paper, the undamped limit of Navier-Stokes equation is studied, that is, the limit behavior of the solution of Navier-Stokes equation with damped term is studied. It is proved that the solutions of Navier-Stokes equations with different damping terms converge to the solutions of Navier-Stokes equations under the same initial value conditions.展开更多
通过在分数阶拉普拉斯耗散的正则化效应和 Coriolis 力的色散效应之间建立新的平衡,我们证明了三维广义 Navier-Stokes-Coriolis 方程组柯西问题在 Besov 空间中的整体适定性。特别地,当旋转速度足够快时,允许初速度任意大。By striking...通过在分数阶拉普拉斯耗散的正则化效应和 Coriolis 力的色散效应之间建立新的平衡,我们证明了三维广义 Navier-Stokes-Coriolis 方程组柯西问题在 Besov 空间中的整体适定性。特别地,当旋转速度足够快时,允许初速度任意大。By striking new balances between the regularizing effects of the fractional Lapla-cian dissipation and the dispersive effects of Coriolis force, we prove the global well-posedness of Cauchy problem for the three-dimensional generalized Navier-Stokes-Coriolis equations in Besov spaces. Particularly, it is shown that initial velocity can bearbitrarily large provided that the speed of rotation is sufficiently high.展开更多
This article gives a general model using specific periodic special functions, that is, degenerate elliptic Weierstrass P functions composed with the LambertW function, whose presence in the governing equations through...This article gives a general model using specific periodic special functions, that is, degenerate elliptic Weierstrass P functions composed with the LambertW function, whose presence in the governing equations through the forcing terms simplify the periodic Navier Stokes equations (PNS) at the centers of arbitrary r balls of the 3-Torus. The continuity equation is satisfied together with spatially periodic boundary conditions. The yicomponent forcing terms consist of a function F as part of its expression that is arbitrarily small in an r ball where it is associated with a singular forcing expression both for inviscid and viscous cases. As a result, a significant simplification occurs with a v3(vifor all velocity components) only governing PDE resulting. The extension of three restricted subspaces in each of the principal directions in the Cartesian plane is shown as the Cartesian product ℋ=Jx,t×Jy,t×Jz,t. On each of these subspaces vi,i=1,2,3is continuous and there exists a linear independent subspace associated with the argument of the W function. Here the 3-Torus is built up from each compact segment of length 2R on each of the axes on the 3 principal directions x, y, and z. The form of the scaled velocities for non zero scaled δis related to the definition of the W function such that e−W(ξ)=W(ξ)ξwhere ξdepends on t and proportional to δ→0for infinite time t. The ratio Wξis equal to 1, making the limit δ→0finite and well defined. Considering r balls where the function F=(x−ai)2+(y−bi)2+(z−ci)2−ηset equal to −1e+rwhere r>0. is such that the forcing is singular at every distance r of centres of cubes each containing an r-ball. At the centre of the balls, the forcing is infinite. The main idea is that a system of singular initial value problems with infinite forcing is to be solved for where the velocities are shown to be locally Hölder continuous. It is proven that the limit of these singular problems shifts the finite time blowup time ti∗for first and higher derivatives to t=∞thereby indicating that there is no finite time blowup. Results in the literature can provide a systematic approach to study both large space and time behaviour for singular solutions to the Navier Stokes equations. Among the references, it has been shown that mathematical tools can be applied to study the asymptotic properties of solutions.展开更多
近些年,带有多项式阻尼项的Navier-Stokes方程被推导且得到研究,并且得出了很多重要结论。本文证明了带有指数阻尼项α(eβ| u |2−1)u(α>0,β>0)的三维Navier-Stokes方程在有界区域上整体吸引子的存在性。In recent years, the N...近些年,带有多项式阻尼项的Navier-Stokes方程被推导且得到研究,并且得出了很多重要结论。本文证明了带有指数阻尼项α(eβ| u |2−1)u(α>0,β>0)的三维Navier-Stokes方程在有界区域上整体吸引子的存在性。In recent years, the Navier-Stokes equations with polynomial damping have been derived and studied, and many important conclusions have been drawn. In this paper, we show that the three-dimensional Navier-Stokes equations with exponential damping α(eβ| u |2−1)u(α>0,β>0)have global attractors in the bounded domain.展开更多
文摘In this article, on the basis of two-level discretizations and multiscale finite element method, two kinds of finite element algorithms for steady Navier-Stokes problem are presented and discussed. The main technique is first to use a standard finite element discretization on a coarse mesh to approximate low frequencies, then to apply the simple and Newton scheme to linearize discretizations on a fine grid. At this process, multiscale finite element method as a stabilized method deals with the lowest equal-order finite element pairs not satisfying the inf-sup condition. Under the uniqueness condition, error analyses for both algorithms are given. Numerical results are reported to demonstrate the effectiveness of the simple and Newton scheme.
基金supported by the National Natural Science Foundation of China(12361044)supported by the National Natural Science Foundation of China(12171024,11971217,11971020)supported by the Academic and Technical Leaders Training Plan of Jiangxi Province(20212BCJ23027)。
文摘This paper is concerned with the global well-posedness of the solution to the compressible Navier-Stokes/Allen-Cahn system and its sharp interface limit in one-dimensional space.For the perturbations with small energy but possibly large oscillations of rarefaction wave solutions near phase separation,and where the strength of the initial phase field could be arbitrarily large,we prove that the solution of the Cauchy problem exists for all time,and converges to the centered rarefaction wave solution of the corresponding standard two-phase Euler equation as the viscosity and the thickness of the interface tend to zero.The proof is mainly based on a scaling argument and a basic energy method.
基金supported by the Key Project of the NSFC(12131010)the NSFC(11771155,12271032)+1 种基金the NSF of Guangdong Province(2021A1515010249,2021A1515010303)supported by the NSFC(11971179,12371205)。
文摘This paper is concerned with the Navier-Stokes/Allen-Cahn system,which is used to model the dynamics of immiscible two-phase flows.We consider a 1D free boundary problem and assume that the viscosity coefficient depends on the density in the form ofη(ρ)=ρ^(α).The existence of unique global H^(2m)-solutions(m∈N)to the free boundary problem is proven for when 0<α<1/4.Furthermore,we obtain the global C^(∞)-solutions if the initial data is smooth.
基金supported by the NSFC(11931013)the GXNSF(2022GXNSFDA035078)。
文摘In this paper,we study the one-dimensional motion of viscous gas near a vacuum,with the gas connecting to a vacuum state with a jump in density.The interface behavior,the pointwise decay rates of the density function and the expanding rates of the interface are obtained with the viscosity coefficientμ(ρ)=ρ^(α)for any 0<α<1;this includes the timeweighted boundedness from below and above.The smoothness of the solution is discussed.Moreover,we construct a class of self-similar classical solutions which exhibit some interesting properties,such as optimal estimates.The present paper extends the results in[Luo T,Xin Z P,Yang T.SIAM J Math Anal,2000,31(6):1175-1191]to the jump boundary conditions case with density-dependent viscosity.
文摘本论文对Navier-Stokes方程非阻尼极限进行了研究,即对带有阻尼项的Navier-Stokes方程解的极限行为进行研究。证明了在相同初值条件下,带有不同阻尼项的Navier-Stokes方程的解u均收敛到Navier-Stokes方程的解v。In this paper, the undamped limit of Navier-Stokes equation is studied, that is, the limit behavior of the solution of Navier-Stokes equation with damped term is studied. It is proved that the solutions of Navier-Stokes equations with different damping terms converge to the solutions of Navier-Stokes equations under the same initial value conditions.
文摘通过在分数阶拉普拉斯耗散的正则化效应和 Coriolis 力的色散效应之间建立新的平衡,我们证明了三维广义 Navier-Stokes-Coriolis 方程组柯西问题在 Besov 空间中的整体适定性。特别地,当旋转速度足够快时,允许初速度任意大。By striking new balances between the regularizing effects of the fractional Lapla-cian dissipation and the dispersive effects of Coriolis force, we prove the global well-posedness of Cauchy problem for the three-dimensional generalized Navier-Stokes-Coriolis equations in Besov spaces. Particularly, it is shown that initial velocity can bearbitrarily large provided that the speed of rotation is sufficiently high.
文摘This article gives a general model using specific periodic special functions, that is, degenerate elliptic Weierstrass P functions composed with the LambertW function, whose presence in the governing equations through the forcing terms simplify the periodic Navier Stokes equations (PNS) at the centers of arbitrary r balls of the 3-Torus. The continuity equation is satisfied together with spatially periodic boundary conditions. The yicomponent forcing terms consist of a function F as part of its expression that is arbitrarily small in an r ball where it is associated with a singular forcing expression both for inviscid and viscous cases. As a result, a significant simplification occurs with a v3(vifor all velocity components) only governing PDE resulting. The extension of three restricted subspaces in each of the principal directions in the Cartesian plane is shown as the Cartesian product ℋ=Jx,t×Jy,t×Jz,t. On each of these subspaces vi,i=1,2,3is continuous and there exists a linear independent subspace associated with the argument of the W function. Here the 3-Torus is built up from each compact segment of length 2R on each of the axes on the 3 principal directions x, y, and z. The form of the scaled velocities for non zero scaled δis related to the definition of the W function such that e−W(ξ)=W(ξ)ξwhere ξdepends on t and proportional to δ→0for infinite time t. The ratio Wξis equal to 1, making the limit δ→0finite and well defined. Considering r balls where the function F=(x−ai)2+(y−bi)2+(z−ci)2−ηset equal to −1e+rwhere r>0. is such that the forcing is singular at every distance r of centres of cubes each containing an r-ball. At the centre of the balls, the forcing is infinite. The main idea is that a system of singular initial value problems with infinite forcing is to be solved for where the velocities are shown to be locally Hölder continuous. It is proven that the limit of these singular problems shifts the finite time blowup time ti∗for first and higher derivatives to t=∞thereby indicating that there is no finite time blowup. Results in the literature can provide a systematic approach to study both large space and time behaviour for singular solutions to the Navier Stokes equations. Among the references, it has been shown that mathematical tools can be applied to study the asymptotic properties of solutions.
文摘近些年,带有多项式阻尼项的Navier-Stokes方程被推导且得到研究,并且得出了很多重要结论。本文证明了带有指数阻尼项α(eβ| u |2−1)u(α>0,β>0)的三维Navier-Stokes方程在有界区域上整体吸引子的存在性。In recent years, the Navier-Stokes equations with polynomial damping have been derived and studied, and many important conclusions have been drawn. In this paper, we show that the three-dimensional Navier-Stokes equations with exponential damping α(eβ| u |2−1)u(α>0,β>0)have global attractors in the bounded domain.
