(Received March 23, 1976)
The motion of viscoelastic fluids between two rollers placed horizontally side by side are theoretically studied by use of the Maxwell model. A normal steady even flow pattern is obtained below a certain critical condition, beyond which ripples first appear. It is shown that the condition depends on the relaxation time of the fluid. Under another condition, a regular striped pattern appears instead of the normal even flow. The relation between the distance between peaks of the stripe and the relaxation time is theoretically obtained and is compared with our experimental results.