<p>This paper is devoted to the study of the Dirichlet problem for the compressible magnetohydrodynamic system with density-dependent viscosities <InlineEquation ID="IEq1"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="21_2025_955_Article_IEq1.gif" Format="GIF" Height="20" Rendition="HTML" Resolution="72" Type="Linedraw" Width="162" /> </InlineMediaObject> <EquationSource Format="TEX">\(\mu =const&gt;0,\lambda =\rho ^\beta \)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>μ</mi> <mo>=</mo> <mi>c</mi> <mi>o</mi> <mi>n</mi> <mi>s</mi> <mi>t</mi> <mo>&gt;</mo> <mn>0</mn> <mo>,</mo> <mi>λ</mi> <mo>=</mo> <msup> <mi>ρ</mi> <mi>β</mi> </msup> </mrow> </math></EquationSource> </InlineEquation> which was first introduced by Vaigant-Kazhikhov [<CitationRef CitationID="CR18">18</CitationRef>] in 1995. By assuming the endpoint case <InlineEquation ID="IEq2"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="21_2025_955_Article_IEq2.gif" Format="GIF" Height="17" Rendition="HTML" Resolution="72" Type="Linedraw" Width="43" /> </InlineMediaObject> <EquationSource Format="TEX">\(\beta =1\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>β</mi> <mo>=</mo> <mn>1</mn> </mrow> </math></EquationSource> </InlineEquation> in the radially spherical symmetric setting, we establish the global existence to strong solution of the two-dimensional system for any large initial data. This also improves the previous work of Huang-Yan [<CitationRef CitationID="CR10">10</CitationRef>] where they proved the similar result for <InlineEquation ID="IEq3"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="21_2025_955_Article_IEq3.gif" Format="GIF" Height="17" Rendition="HTML" Resolution="72" Type="Linedraw" Width="44" /> </InlineMediaObject> <EquationSource Format="TEX">\(\beta &gt;1\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>β</mi> <mo>&gt;</mo> <mn>1</mn> </mrow> </math></EquationSource> </InlineEquation>. Our main idea is to utilize the geometric structure of a 2D spherically symmetric disc and the Sobolev critical embedding inequality of spherically symmetric functions in 2D domains, as well as a refined estimate of the upper bound of the density.</p>

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Global Large Strong Solutions of Radially Symmetric Compressible MHD Equations in 2D Discs

  • Xiangdi Huang,
  • Weili Meng,
  • Anchun Ni

摘要

This paper is devoted to the study of the Dirichlet problem for the compressible magnetohydrodynamic system with density-dependent viscosities \(\mu =const>0,\lambda =\rho ^\beta \) μ = c o n s t > 0 , λ = ρ β which was first introduced by Vaigant-Kazhikhov [18] in 1995. By assuming the endpoint case \(\beta =1\) β = 1 in the radially spherical symmetric setting, we establish the global existence to strong solution of the two-dimensional system for any large initial data. This also improves the previous work of Huang-Yan [10] where they proved the similar result for \(\beta >1\) β > 1 . Our main idea is to utilize the geometric structure of a 2D spherically symmetric disc and the Sobolev critical embedding inequality of spherically symmetric functions in 2D domains, as well as a refined estimate of the upper bound of the density.