When rational functions meet virtual elements: The lightning Virtual Element Method

TL;DR

The paper introduces a lightning Virtual Element Method that computes basis functions explicitly using rational functions, simplifying error analysis and enabling direct point-wise solution access, with efficient parallel implementation.

Contribution

It presents a novel lightning VEM that eliminates stabilization by explicitly computing basis functions with rational approximations, improving analysis and solution accessibility.

Findings

Simplifies a priori error analysis for VEM.

Allows direct point-wise solution evaluation.

Maintains computational efficiency with parallelizable basis construction.

Abstract

We propose a lightning Virtual Element Method that eliminates the stabilisation term by actually computing the virtual component of the local VEM basis functions using a lightning approximation. In particular, the lightning VEM approximates the virtual part of the basis functions using rational functions with poles clustered exponentially close to the corners of each element of the polygonal tessellation. This results in two great advantages. First, the mathematical analysis of a priori error estimates is much easier and essentially identical to the one for any other non-conforming Galerkin discretisation. Second, the fact that the lightning VEM truly computes the basis functions allows the user to access the point-wise value of the numerical solution without needing any reconstruction techniques. The cost of the local construction of the VEM basis is the implementation price that one has to pay for the advantages of the lightning VEM method, but the embarrassingly parallelizable nature of this operation will ultimately result in a cost-efficient scheme almost comparable to standard VEM and FEM.