The paper deals with the accuracy of a nonconforming finite element methods for the well-known equation with the homogeneous Dirichlet conditions on the boundary of – a union of several rectangles.
On nonquasiuniform rectangular grids, the so called ACM’s nonconforming finite elements are considered. The main aim is to study the convergence under the usual assumption that but without such widely used restriction as a quasiuniform structure of the grid. The authors give an estimate of the type in a grid norm. They also present numerical examples for the grids of type and .
In places the presentation is rather strange – for example, the authors call the equation “biharmonic” and write that “the domain is the union of rectangles”.