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arXiv 2307.01992math.AP
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一维两相流模型的整体存在性与最优时间衰减率

Global existence and optimal time decay rate to one-dimensional two-phase flow model

Xushan Huang, Yi Wang

AI总结:

针对由Euler方程与Navier-Stokes方程通过松弛曳力耦合的一维两相流模型,证明了小H¹数据下强解的整体存在性与常平衡态稳定性,推导了最优时间衰减率,解决了一维基本解收敛慢的问题。

摘要:

我们研究了一维(1D)两相流模型解的整体存在性与最优时间衰减率,该模型由可压缩Euler方程与可压缩Navier-Stokes方程通过动量方程上的松弛曳力耦合而成(Euler-Navier-Stokes系统)。首先,我们利用标准连续性论证证明了可压缩Euler-Navier-Stokes系统一维Cauchy问题强解的整体存在性及常平衡态的稳定性,条件为小H¹数据(其二阶导数可任意大)。随后,我们推导了该系统向常平衡态收敛的最优时间衰减率。与多维情形相比,一维情形下基本解收敛速度更慢,直接谱方法难以得到最优衰减率;为此,我们先对高阶导数进行非最优时间加权能量估计,再基于这些估计通过谱分析法完成先验假设并得到最优衰减率。此外,由于两相流耦合曳力项的非守恒形式与衰减率不足,我们在谱分析中需本质性地使用动量变量(m=ρu, M=nω)而非速度变量(u, ω),以完全抵消这些非守恒且时间衰减不足的曳力项。

英文摘要:

We investigate the global existence and optimal time decay rate of solution to the one-dimensional (1D) two-phase flow described by compressible Euler equations coupled with compressible Navier-Stokes equations through the relaxation drag force on the momentum equations (Euler-Navier-Stokes system). First, we prove the global existence of a strong solution and the stability of the constant equilibrium state to 1D Cauchy problem of compressible Euler-Navier-Stokes system by using the standard continuity argument for small $H^{1}$ data while its second order derivative can be large. Then we derive the optimal time decay rate to the constant equilibrium state. Compared with the multi-dimensional case, it is much harder to get the optimal time decay rate by the direct spectrum method due to a slower convergence rate of the fundamental solution in the 1D case. To overcome this main difficulty, we need to first carry out time-weighted energy estimates (not optimal) for higher order derivatives, and based on these time-weighted estimates, we can close a priori assumptions and get the optimal time decay rate by spectral analysis method. Moreover, due to the non-conserved form and insufficient decay rate of the coupled drag force terms between the two-phase flows, we essentially need to use momentum variables $(m= ρu, M=nω)$, rather than velocity variables $(u, ω)$ in the spectrum analysis, to fully cancel out those non-conserved and insufficient time decay drag force terms.

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