It has been shown that

in general.

For Newtonian fluid (water, air, glycerin, etc): . For liquids, viscosity increases with temperature. For gases, viscosity decreases with temperature.

For Non-Newtonian fluid: . Examples are sugar solution and polymers. Therefore, General expression for shear stress

where, m is the flow consistency and n is the flow behaviour index.

• Also known as power–Law model
• also known as apparent viscosity