ENG 103 Fluid Mechanics Mid-Term Exam

Section I. Concept Problems [25%]

1. [5 points] Explain the difference between the no-slip boundary condition and the slip boundary condition.

2. [5 points] If we change the size (radius) of a mercury barometer tube, will the height of the mercury in the tube be different? Justify your answer.

3. [5 points] Define the center of pressure in hydrostatic problems.

4. [5 points] What is the difference between the absolute velocity and the relative velocity? In which situation do we use the relative velocity in the control volume analysis?

5. [5 points] Write down the definition of Newtonian fluids.

Section II. Equation Problems [75%]

Problem 1. [25%] If the pressure in container A is 200 kPa, compute the pressure in container B in kPa. 

Problem 2. [25%] Water at 20°C flows through a 5-cm diameter pipe that has a 180° vertical bend. The total length of pipe between flanges 1 and 2 is 75 cm. When the weight flow rate is 230 N/s, p1=165 kPa (absolute pressure), and p2=134 kPa (absolute pressure). Neglecting pipe weight, determine the force, Fx and FY, that the flanges must withstand for this flow. Note that the weight flow rate is mass flow rate times the gravitational acceleration. x and y coordinates are pointing to the right and downward, respectively. Do not neglect the fluid weight. 

Problem 3. [25%] When the pump draws 220 m3/h of water at 20°C from the reservoir, the total friction head loss is 5m. The flow discharges through a nozzle to the atmosphere. Estimate the pump power in kW delivered to the water.