Abstract
In the approximate solution of boundary value problems for partial differential equations, difference methods are widely used. Grid approximations are most simply constructed when dividing the calculated area into rectangular cells. Usually the grid nodes coincide with the vertices of the cells. In addition to such nodal approximations, grids with nodes in the centers of cells are also used. It is convenient to formulate boundary value problems in terms of invariant operators of vector (tensor) analysis, which are compared with the corresponding grid analogues. The paper builds analogues of gradient and divergence operators on non-standard rectangular grids, the nodes of which consist of both the vertices of the calculated cells and their centers. The proposed approach is illustrated by approximations of the boundary value problem for the stationary two-dimensional convection-diffusion equation. The key features of the construction of approximations for vector problems with orientation to applied problems of solid mechanics are noted.