Page 70 - ebook fluid mechanics_finalize

FLUID MECHANICS

•
m =   A v

A1 v1 A2 v2

in out

• •
m 1 = m 2 , Units kg/s

 A v =  A v
1 1 1 2 2 2

Example 4.2

Oil flows through a pipe at a velocity of 1.6 m/s. The diameter of the pipe is 8 cm.

Calculate discharge and mass flow rate of oil. Take into consideration soil = 0.85.

Solution to Example 4.2

Q = A 1 v
1
1

 ( 08.0 ) 2
= ( ) 6.1 8= . 042 10 − 3 m 3 s /
4

•
m = 
Q

0= . 85 (1000 )( 042.8  10 − 3 )

6= . 836 kg s /

A very simple way to measure the rate at which water is flowing along the pipe is by

catching all the water that is coming out of the pipe in a bucket over a fixed time period.
We can obtain the rate of accumulation of mass by measuring the weight of the water in

the bucket and dividing this by the time taken to collect this water. This is known as the

mass flow rate.

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