English

Real analytic solutions to the divergence equation

Analysis of PDEs 2026-02-26 v1

Abstract

In this paper, we develop a differential-topological method to yield explicit real analytic solutions vv to the divergence equation divRnv=fdiv_{\mathbb{R}^n} v = f on any annali A(R1,R2)={xRn:R1<x<R2}A(R_1 ,R_2) = \{ x \in \mathbb{R}^n : R_1 < |x| < R_2\}, with n2n \geq 2, and 0<R1<R2<0 < R_1 < R_2 < \infty. The prescribed source term ff is supposed to be real analytic on A(R1,R2)={xRn:R1xR2}\overline{A(R_1 , R_2)} = \{ x \in \mathbb{R}^n : R_1 \leq |x| \leq R_2\} satisfying the zero integral condition on A(R1,R2)A(R_1, R_2). The resulting solution vv is a real analytic vector field on A(R1,R2)\overline{A(R_1 , R_2)}, which vanishes on (A(R1,R2))\partial \big( A(R_1, R_2 ) \big ). The method which we develop here is different from the standard Bogovski approach and the Kapitanskii-Pileckas approach. The first main step our method is a clever differential-topological argument, which we develop under the inspiration and guidance of the standard proof of the cohomological statement Hcn(Rn)=RH_c^n \big ( \mathbb{R}^n\big ) = \mathbb{R} in Spviak book A Comprehensive Introduction to Differential Geometry, Vol I. This allows us to reduce the problem to that of solving a linear algebra problem.

Cite

@article{arxiv.2602.21925,
  title  = {Real analytic solutions to the divergence equation},
  author = {Chi Hin Chan and Jun-Shuo Chen and Cheng-Fang Su},
  journal= {arXiv preprint arXiv:2602.21925},
  year   = {2026}
}

Comments

26 pages

R2 v1 2026-07-01T10:52:03.465Z