Question 2 of 4 · Fluid Properties and Flow Regimes · Intermediate · About 19 min
Viscous load on a translating wiper
A rectangular inspection wiper slides horizontally at over a stationary flat support. A layer of Newtonian liquid with dynamic viscosity separates the surfaces. The single wetted face has area . Neglect edge effects and assume linear Couette flow. Find the shear-stress magnitude, the resisting force and the mechanical power required to maintain constant wiper speed.

Given
Relative plate speed: 0.55 m/s
Film thickness: 1.8 mm
Dynamic viscosity: 0.42 Pa·s
Single wetted area: 0.28 m²
Find
Shear stress
Resisting force
Mechanical input power
Assumptions
Steady fully developed linear Newtonian shear.
No pressure-driven contribution or edge friction.
Worked solution
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