Two immiscible, incompressible, viscous fluids having same densities but different viscosities are contained between two infinite horizontal parallel plates, 2 m apart as shown below. The bottom plate is fixed and the upper plate moves to the right with a constant velocity of 3 m/s. With the assumptions of Newtonian fluid, steady, and fully developed laminar flow with zero pressure gradient in all directions, the momentum equations simplify to

                                                         d²u /dy² = 0

If the dynamic viscosity of the lower fluid, μ2, is twice that of the upper fluid, μ1, then the velocity at the interface (round off to two decimal places) is _______ m/s.