Strain Rate Components

Strain Rate Components Consider a fluid element of original lengths dx, dy and dz along the coordinate axes x, y and z respectively. The rate of volumetric dilatation per unit original volume of the element can be written as      [ is a small interval of time] The left hand side of the Eq. (9.7) or (9.8) can be physically identified as the rate of volumetric dilatation per unit volume of a fluid element in motion which is obviously zero for an incompressible flow.