UNIVERSITY OF MAURITIUS

FACULTY OF ENGINEERING

FIRST SEMESTER EXAMINATIONS

NOVEMBER/DECEMBER 2012

PROGRAMME BEng (Hons) Civil Engineering (Full-Time) BEng (Hons) Civil Engineering (Part-Time)

MODULE NAME Fluid Mechanics II/ Fluid Mechanics III

DATE Monday 10 December 2012

MODULE CODE CIVE 3220(5)/ CIVE 3104

TIME 13:30 15:30 Hrs DURATION 2 hours

NO. OF QUESTIONS SET

6 NO. OF QUESTIONS TO BE ATTEMPTED

5

INSTRUCTIONS TO CANDIDATES Answer Any Five (5) Questions

Page 1 of 3

FLUID MECHANICS II/ FLUID MECHANICS II CIVE 3220(5)/CIVE 3104

Answer Any Five (5) Questions Question 1 (a) With the help of outline diagrams, explain the formation of temporary and

permanent springs. [5 marks]

(b) Explain how the hydrological data collection is influenced by the accuracy of the

water balance calculations, with reference to appropriate examples. [8 marks]

(c) Daily rainfall is collected at 12 stations and the average daily rainfall is estimated

by both the thiessen polygon method and the method of isoheyts. How do these two methods compare with regards to accuracy?

[7 marks]

Question 2

(a) The flow rate of a river is estimated by the current meter gauging method.

Explain how the process behind this method enables a relatively accurate estimation of flow. State 2 measures that should be taken to ensure better estimates of flow rate.

[10 marks]

(b) Discuss 5 factors you would consider when selecting an appropriate site to set up a river gauging station.

[5 marks]

(c) A rating curve has been derived for a particular river gauging station. Heavy rainfall damaged the river channel at the station, justify the validity of this rating curve, after this rainfall event.

[5 marks]

Page 2 of 3

FLUID MECHANICS II/ FLUID MECHANICS II CIVE 3220(5)/CIVE 3104

Question 3 (a) Describe the procedures behind the measurements of the following: Infiltration

rate and Evaporation rate. [6 marks]

(b) Five observation wells were used to map the groundwater flow directions within

a region, as follows: OW No.

Eastings Northings Depth to groundwater level

(m)

Surface elevation of

OW (m) 1 2 10 23 215 2 5 9 12 235 3 4 2 56 612 4 6 5 89 504 5 1 3 35 401

Illustrate the groundwater flow direction.

[10 marks]

(c) Explain how the map in part (b) can be used as a decision making tool, while considering possible allocation of a permit for groundwater abstraction for a wet textile industry.

[4 marks]

Question 4 (a) A flow rate of 50m3/s of water flows in a rectangular channel 8m wide with a

depth of 0.5m. Show that a hydraulic jump is likely to occur. [5marks]

(b) Calculate the depth after the jump and the head loss.

[10 marks]

(c) Show by applying Newtons Laws that when a hydraulic jump occurs in a rectangular channel, the depth after the jump is:

h2= h1 [ {(1+8Fr12)} - 1] / 2 [5 marks]

Page 3 of 3

FLUID MECHANICS II/ FLUID MECHANICS II CIVE 3220(5)/CIVE 3104

Question 5 (a) A rectangular channel is 1.2m wide and narrows to 0.6m in a venturiflume. The

depth of entrance and throat are 0.6m and 0.55m respectively. Calculate the flow rate given that Cd = 0.88.

[10marks]

(b) A slightly rough brick-lined trapezoidal channel (n = 0.017) carrying a discharge of Q = 25 m3/sec is to have a longitudinal slope of S0 = 0.0004. Derive the proportions of an efficient trapezoidal channel section having a side slope of 1.5 horizontal: 1 vertical.

[10 marks]

Question 6 (a) A rectangular channel is 3.2m wide and must carry 5m3/s of water with the

minimum specific head. Calculate the depth of flow and mean velocity? [7 marks]

(b) If the channel in (a), must carry flow at constant depth, calculate the slope of the

bed, taking Mannings constant as 0.022. Assuming same flow depth as in (a). [8 marks]

(c) Illustrate the flow profiles of mild slope and steep slope channels.

[5 marks]

END OF QUESTION PAPER

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