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On fractional semilinear wave equations in non-cylindrical domains

Mauro Bonafini, Van Phu Cuong Le, Riccardo Molinarolo

TL;DR

This work studies the fractional semilinear wave equation $\ddot{u}+(-\Delta)^s u+\nabla W(u)=f$ in a time-dependent, non-cylindrical domain $\mathcal{O}$ with exterior Dirichlet conditions and evolving spatial domains $\{\Omega_t\}$. It develops two existence proofs under mild regularity and monotonicity assumptions: a constructive time-discretization scheme and a Lions-type penalty method, both accommodating nonlocal operators and vector-valued maps. The main results guarantee the existence of weak solutions and an energy inequality, with the energy $E(u(t))$ decreasing suitably under forcing. This extends prior cylindrical-domain results to non-cylindrical, time-evolving domains and provides robust variational methods for fractional hyperbolic problems.

Abstract

In this paper, we investigate a class of semilinear wave equations in non-cylindrical time-dependent domains, subject to exterior homogeneous Dirichlet conditions. Under mild regularity and monotonicity assumptions on the evolving spatial domains, we establish existence of weak solutions by two different methods: a constructive time-discretization scheme and a penalty approach. The analysis applies to nonlocal fractional Laplacians and potentials with Lipschitz continuous gradient, and to vector-valued maps.

On fractional semilinear wave equations in non-cylindrical domains

TL;DR

This work studies the fractional semilinear wave equation in a time-dependent, non-cylindrical domain with exterior Dirichlet conditions and evolving spatial domains . It develops two existence proofs under mild regularity and monotonicity assumptions: a constructive time-discretization scheme and a Lions-type penalty method, both accommodating nonlocal operators and vector-valued maps. The main results guarantee the existence of weak solutions and an energy inequality, with the energy decreasing suitably under forcing. This extends prior cylindrical-domain results to non-cylindrical, time-evolving domains and provides robust variational methods for fractional hyperbolic problems.

Abstract

In this paper, we investigate a class of semilinear wave equations in non-cylindrical time-dependent domains, subject to exterior homogeneous Dirichlet conditions. Under mild regularity and monotonicity assumptions on the evolving spatial domains, we establish existence of weak solutions by two different methods: a constructive time-discretization scheme and a penalty approach. The analysis applies to nonlocal fractional Laplacians and potentials with Lipschitz continuous gradient, and to vector-valued maps.
Paper Structure (6 sections, 2 theorems, 130 equations)

This paper contains 6 sections, 2 theorems, 130 equations.

Key Result

Theorem 5

There exists a weak solution $u$ to problem eq:u in the sense of Definition defweaksolu. Moreover, the following energy inequality holds:

Theorems & Definitions (10)

  • Remark 1
  • Remark 2
  • Definition 3: Weak solution
  • Definition 4
  • Theorem 5
  • proof : Proof of Theorem \ref{['thm main result']}
  • proof : Proof of Theorem \ref{['thm main result']}
  • Definition 6
  • Definition 7
  • Theorem 8