“…In this field, several competitive methods have been developed, in particular one could mention the Eulerian-Lagrangian Localized Adjoint Method (ELLAM), see, e.g., [4], [17], [22], the characteristic Galerkin method ( [31]), the Lagrange-Galerkin method ( [43], [46]) as well as semi-Lagrangian ( [28], [45]) and Free-Lagrangian methods ( [13], [19]). While operating on the basis of the Lagrangian concept, this kind of schemes keeps the advantage of the presentation of the solution on a fixed Eulerian grid.…”