“…u(x, 0) = u 0 (x) on Ω, (6) where Ω T = Ω × (0, T ) and n is the unit outward normal to ∂Ω. This problem can be proposed as a mathematical model for the single-phase miscible displacement of one incompressible fluid by another in a porous medium [1,2,4,10,13].…”