Solution Found!
Reconsider Prob. 2–87. If the viscosity of the oil above
Chapter 2, Problem 82P(choose chapter or problem)
Problem 82P
Reconsider Prob. 2–87. If the viscosity of the oil above the moving plate is 4 times that of the oil below the plate, determine the distance of the plate from the bottom surface (h2) that will minimize the force needed to pull the plate between the two oils at constant velocity.
Questions & Answers
QUESTION:
Problem 82P
Reconsider Prob. 2–87. If the viscosity of the oil above the moving plate is 4 times that of the oil below the plate, determine the distance of the plate from the bottom surface (h2) that will minimize the force needed to pull the plate between the two oils at constant velocity.
ANSWER:
Solution 82P
To solve this question, we shall have to consider the shear force equation …..(1), where
is the coefficient of viscosity,
is the contact area between the plate and the fluid and
is the velocity gradient.
Step 1
Given,
Velocity gradient for the upper surface
For the upper surface, the shear force is
For the lower surface, the velocity gradient
For the lower surface, the shear force is
Total shear force