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arXiv 2508.08090math.AP
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粘性两相流的拟不可压 Navier--Stokes/Cahn--Hilliard 模型的弱解与不可压缩极限

Weak solutions and incompressible limit of a quasi-incompressible Navier--Stokes/Cahn--Hilliard model for viscous two-phase flows

Mingwen Fei, Xiang Fei, Daozhi Han, Yadong Liu

AI总结:

本文研究了拟不可压 Navier--Stokes/Cahn--Hilliard 系统在三维周期域中全局弱解的存在性,并利用相对熵方法证明了当密度差趋于零时该模型收敛到模型 H 的不可压缩极限。

摘要:

我们研究了一个拟不可压 Navier--Stokes/Cahn--Hilliard 耦合系统,该系统描述了两种宏观上不混溶的不可压缩粘性流体在微小界面区域内发生部分混合并存在长程相互作用时的运动。我们考虑了质量平均速度下密度不匹配的情形,此时速度场不再无散度,且压力进入化学势方程。我们首先证明了该模型在三维周期域中全局弱解的存在性,其中采用了隐式时间离散以及对近似系统的不动点论证。特别地,通过利用毛细管力的部分阻尼效应,我们获得了序参数的一个新的正则性估计。随后,利用相对熵方法,我们建立了不可压缩极限——当密度差趋于零时,拟不可压两相模型收敛到模型 H。由于压力缺乏正则性,对实现该不可压缩极限至关重要的是一些关于压力的非标准的、关于密度差一致的控制,这些控制由动量方程的结构和序参数改进的正则性推导得出。

英文摘要:

We study a quasi-incompressible Navier--Stokes/Cahn--Hilliard coupled system which describes the motion of two macroscopically immiscible incompressible viscous fluids with partial mixing in a small interfacial region and long-range interactions. The case of unmatched densities with mass-averaged velocity is considered so that the velocity field is no longer divergence-free, and the pressure enters the equation of the chemical potential. We first prove the existence of global weak solutions to the model in a three-dimensional periodic domain, for which the implicit time discretization together with a fixed-point argument to the approximate system is employed. In particular, we obtain a new regularity estimate of the order parameter by exploiting the partial damping effect of the capillary force. Then utilizing the relative entropy method, we establish the incompressible limit -- the quasi-incompressible two-phase model converges to model H as the density difference tends to zero. Crucial to the passage of the incompressible limit, due to the lack of regularity of the pressure, are some non-standard uniform-in-density difference controls of the pressure, which are derived from the structure of the momentum equations and the improved regularity of the order parameter.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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