Those fluids that have no resistance to shear stress are called ideal fluids. The applied shear stress keeps the plate in motion and, when the plate velocity is steady, this shear stress is in equilibrium with the frictional and drag forces within the fluid.Īll fluids, except superfluids (those with a complete absence of viscosity), contain some factor that pose a resistance to shear stress. The applied force per unit area of the plate is called the shear stress. Imagine a fluid between two flat plates one plate is stationary and the other is being moved by a force at a constant velocity parallel to the first plate.
Thus, it can be described as a measure of fluid friction. It is commonly described as a resistance to pouring of a liquid, such as the viscosity different grades of automobile oil. The viscosity of a fluid is an internal measure of its resistance to continuous deformation caused by sliding or shearing forces.
