Chapter 9 : Viscous Flow

Example 9.1 Page No : 307

In [1]:
import math 
		
#initialisation of variables
sg = 0.7
v = 0.05 		#poise
g = 32.2 		#ft/sec**2
w = 62.4 		#lbs/ft**3
		
#CALCULATIONS
u = v*30.5/(g*453.6)
v1 = v/sg
d = w*v1/g
v = u/d
		
#RESULTS
print  'viscocity = %.6f slug/t sec '%(u)
print  ' kinematic viscocity = %.4f cm**2/ sec '%(v1)
print  ' kinematic viscocity = %.6f ft**2/ sec '%(v)

# rounding off error

viscocity = 0.000104 slug/t sec 
 kinematic viscocity = 0.0714 cm**2/ sec 
 kinematic viscocity = 0.000754 ft**2/ sec

Example 9.2 Page No : 308

In [2]:
import math 
		
#initialisation of variables
d = 0.5 		#in
V = 1.   		#ft/sec
l = 200. 		#ft
T = 5. 	    	#degrees
g = 32.2 		#f/sec**2
		
#CALCULATIONS
i = 0.04*V**2*12*4/(g*d)
gf = i*l
		
#RESULTS
print  'loss of head = %.1f ft '%(gf)

loss of head = 23.9 ft

Example 9.3 Page No : 309

In [2]:
import math 
		
#initialisation of variables
g = 32.2 		#ft/sec**2
T = 25. 		#C
dp =8.   		#lbs/in**2
t = 0.005 		#in
w = 3.   		#in
l = 1. 	    	#ft
		
#CALCULATIONS
ut = (0.0179*30.5/(g*453.6))/(1+0.03368*T+0.000221*T**2)
Ql = dp*144*(t/12)**3*3600*6.24/(12*ut*4)
		
#RESULTS
print  'Discharge = %.2f gallons per hour '%(Ql)


#ANSWER GIVEN IN THE TEXTBOOK IS WRONG

Discharge = 2.07 gallons per hour

Example 9.4 Page No : 310

In [4]:
import math 
		
#initialisation of variables
v = 1.25 		#poise
d = 3. 		#in
l = 6. 		#in
t = 0.002 		#in
w = 40. 		#R.P.M
g = 32.2 		#ft/sec**2
		
#CALCULATIONS
u = v*30.5/(453.6*g)
T = u*math.pi**2*(d/12)**3*w*(l/12)/(120*t/12)
hp = T*2*math.pi*w/33000
		
#RESULTS
print  'Horse-power lost in velocit = %.4f '%(hp)

Horse-power lost in velocit = 0.0031

Example 9.5 Page No : 312

In [5]:
import math 
		
#initialisation of variables
w = 750. 		#R.P.M
t = 0.02 		#in
r1 = 9. 		#in
r2 = 5. 		#in
u = 0.003 		#slug/ft sec
		
#CALCULATIONS
T =  u*math.pi*(2*math.pi*w/60)*((r1/24)**4-(r2/24)**4)*2*math.pi*w/(2*t/12*33000)
		
#RESULTS
print  'horse power required to overcome = %.1f hp'%(T)

horse power required to overcome = 0.6 hp