Chapter 2 : Properties of Fluids

Example 2.1 Page No : 9

In [2]:
			
# Variables :
V = 10.;			#in m**3
W = 80.;			#in kN
g = 9.81;			#gravity accelerat
w_water = 9.81;			#specific weight of water

# Calculations and Results
w = W/V;			#specific weight in kN/m**3
print "Specific weight of liquid in kN/m**3 : ",w

mass_density = w*1000/g;			#kg/m**3
print "Mass density of liquid in kg/m**3 : %.2f"%mass_density

specific_gravity = w/w_water;			#unitless
print "Specific gravity : %.3f"%specific_gravity

Specific weight of liquid in kN/m**3 :  8.0
Mass density of liquid in kg/m**3 : 815.49
Specific gravity : 0.815

Example 2.2 Page No : 11

In [3]:
			
# Variables :
p1 = 750.;			#N/cm**2
p2 = 1400.;			#N/cm**2
dvBYV = -0.150;			#in %

# Calculations
dp = p2-p1;			#in N/cm**2
dp = dp*10**4;			#in N/m**2
K = -dp/(dvBYV/100);			#N/m**2

# Results
print "Bulk modulus(N/m**2) : %.2e"%K

Bulk modulus(N/m**2) : 4.33e+09

Example 2.3 Page No : 11

In [5]:
			
# Variables :
Kwater = 2.10*10**6;			#kN/m**2
Kair = 140.;			#kN/m**2
dvBYV = -1.;			#in %

# Calculations and Results
#For Water : 
dp = -Kwater*dvBYV/100;			#kN/m**2
print "Increase of pressure in water in kN/m**2 : %d"%dp

#For Air : 
dp = -Kair*dvBYV/100;			#kN/m**2
print "Increase of pressure in air in kN/m**2",dp

Increase of pressure in water in kN/m**2 : 21000
Increase of pressure in air in kN/m**2 1.4

Example 2.4 Page No : 14

In [6]:
			
# Variables :
A = 0.2;			#m**2
dy = 0.02/100;			#m
du = 20./100;			#cm/s
mu = 0.001;			#Ns/m**2

# Calculations and Results
tau = mu*du/dy;			#in N/m**2
F = tau*A;			#N
print "Force required in N : ",F
Power = F*du;			#Watts
print "Power required in W : ",Power

Force required in N :  0.2
Power required in W :  0.04

Example 2.5 Page No : 16

In [7]:
# Variables :
mu = 0.1;			#Ns/m**2
Sp_gravity_liquid = 2.1;
mass_density_water = 1000.;			#in kg/m**3

# Calculations
rho = Sp_gravity_liquid*mass_density_water;			#kg/m**3
v = mu/rho;			#m**2/sec

# Results
print "Kinematic viscosity of liquid in m**2/sec : %.3e"%v

Kinematic viscosity of liquid in m**2/sec : 4.762e-05

Example 2.6 Page No : 18

In [8]:
import math 
			
# Variables :
d = 2.;							#in mm
d = d/1000;						#in m
sigma_water = 0.073;			#N/m
sigma_mercury = 0.510;			#N/m

# Calculations and Results
#Water-glass contact
w1 = 9.81;			#kN/m**3(specific weight of water)
w1 = w1*10**3;			#N/m**3
theta = 0;			#in degree
h = 4*sigma_water*math.cos(math.radians(theta))/w1/d;			#in mm
print "capillary rise for water glass contact in mm : %.2f"%(h*1000)

#Mercury-glass contact
w2 = 13.6*9.81;			#kN/m**3(specific weight of mercury)
w2 = w2*10**3;			#N/m**3
theta = 130;			#in degree
h = 4*sigma_mercury*math.cos(math.radians(theta))/w2/d;			#in mm
print "capillary rise for mercury glass contact in mm: %.3f"%(h*1000)

capillary rise for water glass contact in mm : 14.88
capillary rise for mercury glass contact in mm: -4.914

Example 2.7 Page No : 20

In [9]:
			
# Variables :
d = 6.;			#in mm
d = d/1000;			#in m
sigma = 0.0755;			#N/m

# Calculations
#At equillibrium : p*math.pi*r**2 = sigma*2*math.pi*r
r = d/2;			#in m
p = 2*sigma/r;			#N/m**2

# Results
print "Intensity of pressure in N/m**2 or Pascals : %.1f"%p

Intensity of pressure in N/m**2 or Pascals : 50.3