határfelületen

Határfelületen is a term used in Hungarian to refer to something that lies on or is defined on the boundary surface of a region or domain. In mathematics, for a domain Ω ⊂ R^n with boundary ∂Ω, határfelületen refers to the points on ∂Ω. Many problems involve conditions prescribed on this boundary, known as boundary conditions.

In the context of partial differential equations, határfelületen conditions include Dirichlet conditions (u|∂Ω = g), Neumann conditions (∂u/∂n|∂Ω = h), and Robin conditions (αu + β ∂u/∂n = r) imposed on the boundary. The concept of traces describes how a function defined inside Ω may have a meaningful restriction to ∂Ω, despite potential irregularities in the interior.

In physics and engineering, határfelületen denotes interfaces between different media or solid boundaries where physical fields are constrained. Examples include the no-slip boundary condition for viscous fluids (velocity vanishes on a solid boundary) or specified electric potential on a conductor’s surface.

Geometrically, a manifold with boundary has a boundary ∂M consisting of boundary points, where tangent and normal structures differ from interior points. Surface integrals and theorems such as Gauss’s and Stokes’ connect integrals over Ω to integrals over its boundary, i.e., over határfelületen, highlighting the boundary’s central role in analysis and geometry.