The Dirichlet problem for Poisson’s equation in a right-isosceles triangle
- 1Departamento de Engenharia Mecânica, Faculdade de Tecnologia, Universidade de Brasília
Abstract
We derive an explicit series representation for the Dirichlet problem for Poisson’s equation in a right-isosceles triangle. Linearity is used to decompose the boundary data into three harmonic subproblems, each carrying the prescribed values on a single side, and a fourth Poisson subproblem with homogeneous Dirichlet conditions. The two leg-driven harmonic fields admit simple sine-hyperbolic expansions in the original coordinates, while the hypotenuse-driven field is obtained after a 45∘ rotation and scaling that maps the domain to a symmetric triangle. The remaining forced problem is treated by an eigenfunction expansion of the Dirichlet Laplacian, with coefficients obtained by orthogonal projection. The resulting formula provides a convenient analytic benchmark for assessing numerical solvers on polygonal domains.
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BibTeX
@article{feijo2026dirichlet,
title = {{The Dirichlet problem for Poisson’s equation in a right-isosceles triangle}},
author = {Juliana Zago Dias Feijó and Vinícius Coutinho da Silva and André von Borries Lopes},
journal = {Boundary Value Problems},
year = {2026},
month = oct,
doi = {10.1186/s13661-026-02344-3},
url = {https://doi.org/10.1186/s13661-026-02344-3},
note = {CC BY},
}
RIS
TY - JOUR
TI - The Dirichlet problem for Poisson’s equation in a right-isosceles triangle
AU - Juliana Zago Dias Feijó
AU - Vinícius Coutinho da Silva
AU - André von Borries Lopes
PY - 2026
DA - 2026/10/25
JO - Boundary Value Problems
DO - 10.1186/s13661-026-02344-3
UR - https://doi.org/10.1186/s13661-026-02344-3
AB - We derive an explicit series representation for the Dirichlet problem for Poisson’s equation in a right-isosceles triangle. Linearity is used to decompose the boundary data into three harmonic subproblems, each carrying the prescribed values on a single side, and a fourth Poisson subproblem with homogeneous Dirichlet conditions. The two leg-driven harmonic fields admit simple sine-hyperbolic expansions in the original coordinates, while the hypotenuse-driven field is obtained after a 45∘ rotation and scaling that maps the domain to a symmetric triangle. The remaining forced problem is treated by an eigenfunction expansion of the Dirichlet Laplacian, with coefficients obtained by orthogonal projection. The resulting formula provides a convenient analytic benchmark for assessing numerical solvers on polygonal domains.
SN - 1687-2770
SN - 1687-2762
ER -