Two-Phase Heat Conductors with a Surface of the Constant Flow Property

Lorenzo Cavallina, Rolando Magnanini, Shigeru Sakaguchi

Research output: Contribution to journalArticlepeer-review

7 Citations (Scopus)


We consider a two-phase heat conductor in RN with N≥ 2 consisting of a core and a shell with different constant conductivities. We study the role played by radial symmetry for overdetermined problems of elliptic and parabolic type. First of all, with the aid of the implicit function theorem, we give a counterexample to radial symmetry for some two-phase elliptic overdetermined boundary value problems of Serrin type. Afterwards, we consider the following setting for a two-phase parabolic overdetermined problem. We suppose that, initially, the conductor has temperature 0 and, at all times, its boundary is kept at temperature 1. A hypersurface in the domain has the constant flow property if at every of its points the heat flux across surface only depends on time. It is shown that the structure of the conductor must be spherical, if either there is a surface of the constant flow property in the shell near the boundary or a connected component of the boundary of the heat conductor is a surface of the constant flow property. Also, by assuming that the medium outside the conductor has a possibly different conductivity, we consider a Cauchy problem in which the conductor has initial inside temperature 0 and outside temperature 1. We then show that a quite similar symmetry result holds true.

Original languageEnglish
Pages (from-to)312-345
Number of pages34
JournalJournal of Geometric Analysis
Issue number1
Publication statusPublished - 2021 Jan


  • Cauchy problem
  • Constant flow property
  • Diffusion equation
  • Heat equation
  • Initial-boundary value problem
  • Overdetermined problem
  • Symmetry
  • Transmission condition
  • Two-phase heat conductor

ASJC Scopus subject areas

  • Geometry and Topology


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