A method for the numerical solution of differential problems with partial derivatives, particularly for Laplacian fields, is proposed. It consists in the discretisation of the Laplacian equation by means of a curvilinear grid with orthogonal grid lines. The procedure for the determination of the equations in the grid points and for the introduction of Neumann's or Dirichlet's boundary conditions in 2-dimensional or 3-dimensional (with rotation symmetry) Laplacian problems is described for this method. The properties of the systems made up of such equations are also described, especially with regard to the iterative methods for their solution.