non-Newtonian fluid
A non-Newtonian fluid is one that does not obey Newton's viscosity law, which states that viscosity should remain constant regardless of stress. When non-Newtonian fluids are forced, their viscosity can change from liquid to solid. When shaken, ketchup, for example, gets runnier, making it a non-Newtonian fluid.
Many salt solutions and molten polymers, as well as many everyday items as custard,[1] toothpaste, starch suspensions, corn starch, paint, blood, melted butter, and shampoo, are non-Newtonian fluids.
Most non-Newtonian fluids' viscosity (the progressive deformation caused by shear or tensile stresses) is determined by shear rate or shear rate history. However, some non-Newtonian fluids with shear-independent viscosity show normal stress differences or other non-Newtonian characteristics. In a Newtonian fluid, the relationship between shear stress and shear rate is linear, passing through the origin, with the coefficient of viscosity as the proportionality constant. The relationship between shear stress and shear rate in a non-Newtonian fluid is different. The viscosity of the fluid might potentially change over time. As a result, a constant coefficient.