B. Rummler

collaborators

3 papers

math.AP2026

Explicit formulas for gradients and the divergence in n-dimensional spherical coordinates

Bernd Rummler, Gudrun Thäter

We use the Laplacian in n-dimensional spherical coordinates (n>1) to write the divergence of a vector field defined on radially symmetric domains in the context of vector calculus.…

math.AP2026

Exact Poincare Constants in n-dimensional Annuli

Bernd Rummler, Michael Ruzicka, Gudrun Thäter

We study $n$ -dimensional annuli for $n \in {2, \dots, N}$ with $N < \infty$ . We choose a non-dimensional setting such that for any fixed $n$ and given number $A > 0$ the…

math.AP2025

Natural convection in the horizontal annulus: critical Rayleigh number for the steady problem

Arianna Passerini, Bernd Rummler, Michael Ruzicka +1

For the 2D Oberbeck-Boussinesq system in an annulus we are looking for the critical Rayleigh number for which the (nonzero) basic flow loses stability. For this we consider the cor…