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1. 1
King Saud University ChE 312
College of Engineering Tutorial # 3
Chemical Engineering Dept. First semester 1430
Momentum Transfer
1. The distance the tow parallel plates in figure 1 is 0.00914 m and the lower
plate is being pulled at a relative velocity of 0.366 m/s greater than the top
plate. The fluid used is soybean oil with a viscosity 410-2
Pa*s at 303 K.
a) Calculate the shear stress t and the shear rate using English units.
b) Repeat a) using SI units.
c) If glycerol at 293 K having a viscosity of 1.069 kg/m*s is used instead
of soybean oil, what relative velocity in m/s is needed using the same
distance between plates so that the same shear stress is obtained as in
part a)? Also, what is the new shear rate?
Figure 1
2. Using figure 1, the lower plate is being pulled at a relative velocity of 0.40
m/s greater than the top plate. The fluid used is water at 24°C.
a) How far apart should the tow plates be placed so that the shear stress t
is 0.30 N/m2
? Calculate the shear stress.
b) If oil with a viscosity of 2.010-2
Pa*s is used instead at the same plate
spacing and velocity as in part a), what are the shear stress and shear
rate?
3. Determine whether the following liquid is Newtonian or not?
Shear rate s-1
10 20 50 100 200 400 600 1000 2000
Shear stress
(N/m2
) 10-4
2.2 3.1 4.4 5.8 7.4 9.8 11.1 13.9 17.0
Dvz
z
y
Dy
F

2. 2
4. Whole milk at 293 K having a density of 1030 kg/m3
and viscosity of 2.12
cp is flowing at the rate of 0.605 kg/s in a glass pipe having a diameter of
63.5 mm.
a) Calculate the Reynolds number. Is this flow turbulent or laminar?.
b) Calculate the flow rate needed in m3
/s for a Reynolds number of 2100
and velocity in m/s.
5. An oil is being pumped inside a 10.0-mm-diameter pipe at a Reynolds
number of 2100. The oil density is 855 kg/m3
and the viscosity is 2.110-2
Pa*s.
a) What is the velocity in the pipe?
b) It is desired to maintain the same Reynolds number of 2100 and the
same velocity as in part a) using a second fluid with a density of 925
kg/m3 and a viscosity of 1.510-2
Pa*s. What pipe diameter should be
used?