MODULE 3

Section 2:   

Pressure Drop and Friction Factor

Section 3:   

Hear Transfer Coefficient

Section 4: 

Convection With Phase Change

Viscosity forces (or shear stresses) occur in real flows due to the friction of fluid layers with different velocities. For the one-dimensional flow shown in figure 1, the velocity u is parallel to the wall and shear stresses occur in plans parallel to the wall.

Figure 1. Shear stress

The shear stress is estimated by Newton’s equation:

(3.3)

where

m is the dynamic viscosity 

and  

       is the velocity gradient.

The expression of the shear stress can also be presented in terms of the kinematics viscosity instead of the dynamic viscosity:

(3.4)

where r is the fluid density

 Previous page

 Next page

2/6