# Chapter 8 :Viscosity and Viscous Flow¶

## Example 8.1 Page No : 157¶

In [1]:
import math

#initialisation of variables
v= 10.01 	#poise velocity
g= 32.2 	#ft/sec**2
d= 30.48 	#cm
w= 453.6 	#gm

#CALCULATIONS
M= round(v*d/w,3)
F= M/g

#RESULTS
print  'Pound in unit of mass = %.3f lb/ft sec absolute units'%(M)
print  ' Pound in unit of force = %.4f slugs/ft sec'%(F)
Pound in unit of mass = 0.673 lb/ft sec absolute units
Pound in unit of force = 0.0209 slugs/ft sec

## Example 8.2 Page No : 157¶

In [2]:
import math

#initialisation of variables
W= 20.   	#tons/hr oil
l= 1000. 	#ft long
w= 57.   	#lb/ft**3 weighs
kv= 0.0205 	#ft**2/sec kinematic viscisity
d= 6.    	#in diameter
g= 32.2 	#ft/sec**2

#CALCULATIONS
Q= W*2240/(3600*w)
A= math.pi*(d/12)**2/4
v= Q/A
R= v*(d/12)/kv
n= w*kv/g
P= 32*v*n*l/((d/12)**2*w)
HP= P*2240*W/(3600*500)

#RESULTS
print  'Reynolds number = %.1f '%(R)
print  ' H.P required = %.2f hp'%(HP)

#The answer is a bit different due to rounding off error in textbook
Reynolds number = 27.1
H.P required = 2.26 hp

## Example 8.4 Page No : 159¶

In [3]:
import math

#initialisation of variables
n= 0.0067 	#poise
l= 10. 	#ft length
w= 62. 	#lb/ft**3 density
d= 1. 	#in
Q= 2. 	#ft**2/sec
sm= 13.57
k1= 0.003
k2= 0.0725
r= 0.3
g= 32.2 	#ft/sec**2

#CALCULATIONS
n1= n*30.48/453.6
v= Q*4/(60*math.pi*(d/12)**2)
RN= v*(d/12)*w/n1
f= k1+(k2/RN**r)
hf= 4*f*l*v**2/(2*g*(d/12))
hl= hf*12/sm

#RESULTS
print  'Head lost in inches of mercury = %.2f in'%(hl)
Head lost in inches of mercury = 1.37 in

## Example 8.5 Page No : 160¶

In [1]:
import math

#initialisation of variables
n= 0.91 	#poise
g= 32.2 	#ft/sec
N= 300. 	#r.p.m
t= 0.01 	#in
r1= 0.25 	#ft
r2= 1./6 	#ft

#CALCULATIONS
n1= n*30.48/(454*g)
A= N*2*math.pi/60
t1= t/12
hp= math.pi*A**2*n1*(r1**4-r2**4)/(t1*1100)

#RESULTS
print  'Horse Power lost = %.4f '%(hp)
Horse Power lost = 0.0201

## Example 8.6 Page No : 162¶

In [5]:
import math

#initialisation of variables
vw= 0.3 	#ft/sec
dw= 1.  	#in
da= 12. 	#in
ww= 62.3 	#lb/ft**3
wa= 0.075 	#lb/ft**3
nw= 0.01 	#poise
na= 0.00018 	#poise

#CALCULATIONS
va= vw*dw*ww*na/(nw*da*wa)

#RESULTS
print  'critical velocity of air = %.3f ft/sec'%(va)
critical velocity of air = 0.374 ft/sec

## Example 8.7 Page No : 162¶

In [6]:
import math

#initialisation of variables
dm= 0.75 	#in
dt= 0.25 	#in
dP= 10.4 	#lb/in**2
rd= 0.84
w= 62.4 	#lb/ft**3
g= 32.2 	#ft/sec**2

#CALCULATIONS
v1= math.sqrt(dP*144*g/(rd*w*((dm/dt)**4-1)))
Q= math.pi*dm**2*v1*60*w/(4*144*10)

#RESULTS
print  'Discharge rate = %.1f gal.min'%(Q)
Discharge rate = 3.9 gal.min