Consider a two-dimensional fluid element, a square ABCD for simplicity. when the fluid flows this element is subject to various forces and as a result undergoes a complex motion and a possible deformation as indicated in Fig.4.5 and assumes a shape like A`B`C`D`. It appears that the complex deformation of the element can be split into four basic constituents -
Translation
Linear Deformation
Rotation
Angular Deformation
Figure 4.5: Deformation of A fluid Element
Figure 4.6 : Basic Deformation of A fluid Element
These elemental deformations have been sketched in
Fig.4.6 . Let us now consider each of these separately.
