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arXiv 2004.09781math.AP
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具有Maxwell-Stefan扩散的理想气体混合物的广义解理论

A theory of generalised solutions for ideal gas mixtures with Maxwell-Stefan diffusion

Pierre-Etienne Druet

摘要:

在Giovangigli对多组分流动数学的开创性工作之后,人们多次尝试为描述流体混合物动力学的偏微分方程引入全局弱解。虽然由于Chen和Jüngel(等温情况)或Marion和Temam的结果,具有恒定密度的不可压缩情况被充分地阐明,但是对于气体混合物的弱解理论及其相应的混合抛物-双曲型方程,仍然存在一些未解决的问题。例如,Mucha、Pokorny和Zatorska通过Bresch-Desjardins技术和防止真空的压力正则化,证明了稳定双曲分量的可能性。德赖尔、德鲁埃、加维斯基和古尔克的结果避免了机械前稳定化,但在稀极限下,昂萨格矩阵在某些子空间上一致为正的数学假设导致无限扩散速度,这与扩散通量的麦克斯韦-斯特凡形式不相容。本文证明了具有自然扩散的等温理想可压缩混合方程整体弱解的存在性。主要的新工具是一个渐近条件施加在低压的二进制麦克斯韦-斯特凡扩散系数,这可能会补偿极端行为的弱解在稀薄制度。

英文摘要:

After the pioneering work by Giovangigli on mathematics of multicomponent flows, several attempts were made to introduce global weak solutions for the PDEs describing the dynamics of fluid mixtures. While the incompressible case with constant density was enlighted well enough due to results by Chen and Jüngel (isothermal case), or Marion and Temam, some open questions remain for the weak solution theory of gas mixtures with their corresponding equations of mixed parabolic-hyperbolic type. For instance, Mucha, Pokorny and Zatorska showed the possibility to stabilise the hyperbolic component by means of the Bresch-Desjardins technique and a regularisation of pressure preventing vacuum. The result by Dreyer, Druet, Gajewski and Guhlke avoids ex machina stabilisations, but the mathematical assumption that the Onsager matrix is uniformly positive on certain subspaces leads, in the dilute limit, to infinite diffusion velocities which are not compatible with the Maxwell-Stefan form of diffusion fluxes. In this paper, we prove the existence of global weak solutions for isothermal and ideal compressible mixtures with natural diffusion. The main new tool is an asymptotic condition imposed at low pressure on the binary Maxwell-Stefan diffusivities, which compensates possibly extreme behaviour of weak solutions in the rarefied regime.

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