MIXED FINITE ELEMENTS METHODS TRANSITIONAL WAVES MODELING AND SIMULATION OF MULTI-SCALE PHENOMENA THREE-PHASE FLOW CENTRAL SCHEMES FOR HYPERBOLIC CONSERVATION LAWS RIEMANN PROBLEM SECONDARY RECOVERY HETEROGENEOUS POROUS MEDIA HETEROGENEITY FLOW IN POROUS MEDIA RANDOM POROUS MEDIA DEGENERATE PARABOLIC SYSTEM NUMERICAL METHODS FOR PDES FLUID DYNAMICS