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991.
992.
Zuoshunhua Shi 《Journal of Differential Equations》2018,264(3):1550-1580
In this paper, we mainly study the existence of self-similar solutions of stationary Navier–Stokes equations for dimension . For , if the external force is axisymmetric, scaling invariant, continuous away from the origin and small enough on the sphere , we shall prove that there exists a family of axisymmetric self-similar solutions which can be arbitrarily large in the class . Moreover, for axisymmetric external forces without swirl, corresponding to this family, the momentum flux of the flow along the symmetry axis can take any real number. However, there are no regular () axisymmetric self-similar solutions provided that the external force is a large multiple of some scaling invariant axisymmetric F which cannot be driven by a potential. In the case of dimension 4, there always exists at least one self-similar solution to the stationary Navier–Stokes equations with any scaling invariant external force in . 相似文献
993.
Haibo Cui Haiyan Yin Jinshun Zhang Changjiang Zhu 《Journal of Differential Equations》2018,264(7):4564-4602
In this paper, we are concerned with the asymptotic behavior of solutions to the system of Euler equations with time-depending damping, in particular, include the constant coefficient damping. We rigorously prove that the solutions time-asymptotically converge to the diffusion wave whose profile is self-similar solution to the corresponding parabolic equation, which justifies Darcy's law. Compared with previous results about Euler equations with constant coefficient damping obtained by Hsiao and Liu (1992) [2], and Nishihara (1996) [9], we obtain a general result when the initial perturbation belongs to the same space, i.e. . Our proof is based on the classical energy method. 相似文献
994.
We develop the rough path counterpart of Itô stochastic integration and differential equations driven by general semimartingales. This significantly enlarges the classes of (Itô/forward) stochastic differential equations treatable with pathwise methods. A number of applications are discussed. 相似文献
995.
996.
Kevin E.M. Church Robert Smith? 《Journal of Mathematical Analysis and Applications》2018,457(1):616-644
The time-scale tolerance for linear ordinary impulsive differential equations is introduced. How large the time-scale tolerance is directly reflects the degree to which the qualitative dynamics of the linear impulsive system can be affected by replacing the impulse effect with a continuous (as opposed to discontinuous, impulsive) perturbation, producing what is known as an impulse extension equation. Theoretical properties related to the existence of the time-scale tolerance are given for periodic systems, as are algorithms to compute them. Some methods are presented for general, aperiodic systems. Additionally, sufficient conditions for the convergence of solutions of impulse extension equations to the solutions of their associated impulsive differential equation are proven. Counterexamples are provided. 相似文献
997.
We study the initial-boundary value problem for the one dimensional EulerBoltzmann equation with reflection boundary condition. For initial data with small total variation, we use a modified Glimm scheme to construct the global approximate solutions(U_(△t,d), I_(△t,d)) and prove that there is a subsequence of the approximate solutions which is convergent to the global solution. 相似文献
998.
Simulation of Viscous Flows Around a Moving Airfoil by Field Velocity Method with Viscous Flux Correction 下载免费PDF全文
Ning Gu Zhiliang Lu & Tongqing Guo 《advances in applied mathematics and mechanics.》2012,4(3):294-310
Based on the field velocity method, a novel approach for simulating unsteady
pitching and plunging motion of an airfoil is presented in this paper. Responses
to pitching and plunging motions of the airfoil are simulated under different
conditions. The obtained results are compared with those of moving grid
method and good agreement is achieved. In the conventional field velocity method,
the Euler solver is usually used to simulate the movement of the airfoil. However,
when viscous effect is considered, unsteady Navier-Stokes equations have to be
solved and the viscous flux correction must be taken into account. In this work, the
viscous flux correction is introduced into the conventional field velocity method
when non-uniform grid speed distribution is occurred. Numerical experiments for
the flow around NACA0012 airfoil showed that the proposed approach can well
simulate viscous moving boundary flow problems. 相似文献
999.
针对在Z型管道中传输的高能量密度激光束受到的气体热效应问题,采用光波标量衍射方程计算光传输、N-S方程计算管道内流场,仿真计算了以不同的速度沿管道轴向吹入对激光能量无吸收的气体时,由于气流扰动对出射光束远场光斑质量的影响。结果表明,在采用纵向吹气减小气体热效应对光束传输的影响时,应尽可能采用大气量、低流速的方案,既有利于排空管道中的杂质气体,减小气体热效应,又有利于减小管道中流场密度分布的不均匀性,从而保证出射光束的质量。 相似文献
1000.
刘玉记 《数学年刊A辑(中文版)》2018,39(3):309-330
将具有脉冲的分数阶Bagley-Torvik微分方程边值问题巧妙地转化为积分方程,定义加权Banach空间及全连续算子,运用不动点定理获得该边值问题解的存在性定理.举例说明了定理的应用.最后提出有趣的研究问题. 相似文献