shear stress between two parallel plates

[warickwrx]

Hi

When calculating the shear stress between two parallel plates which are moving in the same direction at different velocities with a fluid sandwiched in between is it advisable to subtract the two velocities namely ( V1 -V2 ), and assume the one bottom plate as now stationary with the resultant velocity as now only being the total for the top. The reason I ask is that one would think the shear stress in the liquid between the plates is less if both moving in the same direction. So hypothetical if a top plate moves at 2 m/s and bottom at 1m/s then new velocity is 1m/s for top with the bottom stationary.

thanks

 

[Compositepro]

Yes, of course. Only the relative velocity between the plates is of importance.

 

[hydtools]

Where is the input force applied? Is one plate driving the other through the shear strength of the fluid sandwiched between the two? Or does each plate have independent driving force?

Ted

 

[Compositepro]

It does not matter how the force is applied.