A liquid initially fills the inside of a vertical tube of length L and inside diameter D. The tube is capped at both ends. Then the caps are suddenly removed, and the liquid flows out of the bottom of the tube as a continuous stream until the tube is nearly empty. Assume that the flow inside the tube is laminar and that the force of the surrounding air on the stream is negligible. Gravity provides the driving force for the flow. What forces provide resistance to flow? List the parameters you think affect the rate of flow of the liquid from the tube. Give the dimensions of each parameter.
The Attempt at a Solution
Gravity (L/t^2), Tube diameter (L), liquid density (m/L^3), liquid viscosity (m/L*t),
The forces the provide resistance to flow are inertia and viscosity(friction).
My questions to viewers: Does viscosity take care of friction at the boundary layer? Does the velocity depend on the tube length? I did not include it because it was not included in a similar example problem.