Two immiscible, incompressible, viscous fluids with the same densities but different viscosities are contained between two infinite horizontal parallel plates 2 m apart, split into two equal 1 m layers. The bottom plate is fixed; the upper plate moves at a constant 3 m/s. Assuming steady, fully-developed laminar flow with zero pressure gradient, if the dynamic viscosity of the lower fluid μ2 is twice that of the upper fluid μ1, the velocity at the interface (round off to two decimal places) is ___ m/s.