Link:http://output.to/sideway/default.asp?qno=100100005 Viscosity Fluid PropertiesViscosityViscosity or Dynamic Viscosity is used to describe the fluidity property or the internal resistance of a fluid to motion. From experimental observation, when a fluid flows over a solid surface, it comes to a complete stop at the surface and sticks on it. This is known as the no-slip condition and all liquids and gases satisfy this condition. When considering a hypothetical experiment in which fluid is located between the small gap of two parallel plates. By fixing the bottom plate at rest and moving the upper plate at a constant velocity, the fluid deforms continuously under the shear force. ![]()
Because of the no-slip condition, the fluid contacts with the bottom fixed plate
has a zero velocity, while the fluid contacts with the upper moving plate moves
with the same upper plate velocity. As
For steady laminar flow, the velocity profile of the flow varies linearly away
from the fixed plate, i.e.
For a small time increment
From experimental results, the rate of shearing strain
![]()
Fluids with shearing stress linearly proportion to the rate of shearing strain
that can be described by a simple constant are called Newtonian fluids,
![]()
The ratio of dynamic viscosity to density usually appears and is named as
kinematic viscosity, i.e.
|
Sideway BICK Blog 25/01 |