Chapter 7 : Similitude and Dimensional Analysis

Example 7.2 Page No : 192

	
#Initialization of variables
Dratio = 8.
mu = 0.0006
rho = 52/32.2
vm = 1.22*10**-5 	# lbs/ft**2
V = 45.             # velocity - fps
Fm = 0.8
	
#calculations
vp = round(mu/rho,7)
Vm = vm*V/(Dratio*vp)
Fratio = rho*V**2 /(1.94*Vm**2 *Dratio**2)
Fp = Fratio*Fm

#Results
print "velocity  =  %.2f fps"%(Vm)
print " Drag force  =  %d lb"%(Fp)

# note : The answer given in textbook for vp is wrong. Hence, the difference in answers

velocity  =  0.18 fps
 Drag force  =  617 lb

Example 7.3 Page No : 195

import math 
	
#Initialization of variables
L = 50.
Fm = 0.02 	#N
Vm = 1. 	#m/s
	
#calculations
Fp = L**3 *Fm 
Fp = Fp*0.2248
Vp = math.sqrt(L) *Vm
Vp = Vp*3.28
Hp = Fp*Vp/550
	
#Results
print "Required horsepower  =  %.1f hp"%(Hp)

Required horsepower  =  23.7 hp