APPROXIMATION AND ITS OPTIMAL ERROR ESTIMATE OF DISPLACEMENT OF TWO-PHASE INCOMPRESSIBLE FLOW BY MIXED FINITE ELEMENT AND A MODIFIED METHOD OF CHARACTERISTICS

Ⅰ. INTRODUCTIONThe displacement of one incompressible fluid by another in porous media has very important significance in engineering and production. In recent years Profs. J. Douglas, Jr., R. E. Ewing and Yuan Yirang and others proposed a kind of numerical simulation on the basis of combining mixed finite dement procedures with a modified method of characteristics