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Self-Similar Solutions to the Hele-Shaw Problem with Surface Tension

Siddhant Agrawal, Neel Patel

TL;DR

This work addresses the dynamics of a single-phase Hele-Shaw interface with surface tension in the plane, focusing on interfaces that begin with a corner. The authors develop a conformal-coordinate framework to derive a third-order nonlocal self-similar equation dominated by the Hilbert transform, and they first analyze a linear approximation to understand the asymptotics. Using a weighted functional-analytic setup, they prove existence, decay, and regularity for the linear problem via a δ-regularized variational scheme, then extend to the full nonlinear equation through a contraction mapping for small corner perturbations, yielding a family of self-similar solutions that are smooth for $t>0$. The results provide explicit structural insight into corner dynamics under surface tension and establish a rigorous foundation for self-similar free-boundary behavior in Hele-Shaw-type problems.

Abstract

We consider the Hele-Shaw problem with surface tension in an infinite domain. We prove the existence of a family of self-similar solutions. At $t=0$, these solutions have a corner of angle $θ$ with $ 0 < |θ- π| \ll 1$, and for $t>0$, the solutions are smooth.

Self-Similar Solutions to the Hele-Shaw Problem with Surface Tension

TL;DR

This work addresses the dynamics of a single-phase Hele-Shaw interface with surface tension in the plane, focusing on interfaces that begin with a corner. The authors develop a conformal-coordinate framework to derive a third-order nonlocal self-similar equation dominated by the Hilbert transform, and they first analyze a linear approximation to understand the asymptotics. Using a weighted functional-analytic setup, they prove existence, decay, and regularity for the linear problem via a δ-regularized variational scheme, then extend to the full nonlinear equation through a contraction mapping for small corner perturbations, yielding a family of self-similar solutions that are smooth for . The results provide explicit structural insight into corner dynamics under surface tension and establish a rigorous foundation for self-similar free-boundary behavior in Hele-Shaw-type problems.

Abstract

We consider the Hele-Shaw problem with surface tension in an infinite domain. We prove the existence of a family of self-similar solutions. At , these solutions have a corner of angle with , and for , the solutions are smooth.

Paper Structure

This paper contains 13 sections, 27 theorems, 265 equations.

Key Result

Lemma 2.1

Let $1<p<\infty$ and let $F(z)$ be a holomorphic function in the lower half plane with $F(z) \to 0$ as $z\to \infty$. Then the following are equivalent:

Theorems & Definitions (49)

  • Lemma 2.1: Ti86
  • Theorem 3.1
  • Proposition 4.1
  • proof
  • Proposition 4.2
  • proof
  • Theorem 5.1
  • Theorem 5.2: Lax-Milgram
  • Lemma 5.3
  • proof
  • ...and 39 more