We introduce the nonconforming Virtual Element Method (VEM) for the approximation of second order elliptic problems. We present the construction of the new element in two and three dimensions, highlighting the main differences with the conforming VEM and the classical nonconforming finite element methods. We provide the error analysis and establish the equivalence with a family of mimetic finite difference methods. Numerical experiments verify the theory and validate the performance of the proposed method.

We develop and analyse a new family of virtual element methods on unstructured polygonal meshes for the diffusion problem in primal form, which uses arbitrarily regular discrete spaces V_h ⊂ C^α, α ∈ ℕ. The degrees of freedom are (a) solution and derivative values of various degrees at suitable nodes and (b) solution moments inside polygons. The convergence of the method is proved theoretically and an optimal error estimate is derived. Numerical experiments confirm the convergence rate that is expected from the theory.