When a solution having a linear concentration gradient along the gravitational direction is heated from a vertical wall and cooled from an opposing vertical wall, multilayered roll cells separated by near-horiwntal sharp interfaces are observed. This paper presents a finite-element computational scheme to simulate this phenomenon. Computations were carried out for Pr = 6, Le = 100, A = 8, N = 2 or S, and Ra = I04or 105. In the numerical simulation, two roll cells appeared, one just below the top free surface and one just above the bottom plane. Subsequently, one or several roll cells appeared between them, and finally they converged to a single roll cell.