Fluid Flow

Problems

Explain why blood corpuscles tend to flow down the center of blood vessels and not along the edges. (Do not ignore viscosity.)

A 15 cm radius air duct is used to replenish the air of a room 10 m × 6.0 m × 3.0 m every 10 minutes. Determine the following quantities inside the duct (assuming there are no significant changes in the density of the air entering or exiting the duct)…
1. the volume flow rate in m³/s?
2. the mass flow rate in kg/s?
3. the speed of the air in m/s?
If the wind blows at 25 m/s over a house, what is the net force on an 8×20 m roof?
Water at a pressure of 3.3 atm at street level flows into an office building at a speed of 0.50 m/s through a pipe 5.0 cm in diameter. The pipe tapers down to 2.5 cm diameter by the top floor, 25 m above. Calculate the flow velocity and pressure in this pipe on the top floor.
Blood exits the heart at 30 cm/s. By the time it reaches the capillaries, it's slowed to 1 mm/s.
1. If the cross sectional area of the aorta is 3 cm², what is the total cross sectional area of the capillaries?
2. If the cross sectional area of the superior and inferior vena cavas is 18 cm², what is the speed of the blood returning to the heart?
A hypodermic syringe filled with normal saline solution has an inner barrel diameter of 10.4 mm and an inner needle diameter of 0.260 mm.
1. How fast does the saline solution exit the needle orifice if the plunger moves at 1 mm/s?
2. What pressure at the plunger head is needed to overcome an intravenous pressure of 1.9 kPa (14 torr)?
3. What minimum force should be applied to the thumb rest?