Meaning
Physical movement of matter that does not follow the constant viscosity relationship described by Newton. In non-newtonian fluid flow, the resistance to deformation changes according to the magnitude of the applied shear rate. Many industrial materials including paints and biological fluids exhibit this behavior.
The study of these patterns allows for the precise sizing of pumps and mixers.
Viscosity Change
Thinning or thickening occurs as the internal structure of the substance rearranges under stress. During non-newtonian fluid flow, the apparent viscosity might drop by several orders of magnitude as speed increases. This property is exploited to make coatings that spread easily when brushed but stay thick when at rest.
Stress Response
Elasticity and time dependency introduce complexity into the transport equations. Some examples of non-newtonian fluid flow show memory where the current state depends on the history of deformation. This requires specialized numerical solvers to predict behavior in complex geometries.
Processing Limit
Flow instabilities arise when the shear rates exceed the structural integrity of the fluid. Managing non-newtonian fluid flow in a factory environment prevents the clogging of nozzles and the overheating of drive motors. Careful control of temperature and concentration keeps the material within the desired flow regime.
If the shear becomes too intense, the fluid may undergo a phase transition or a permanent breakdown of its molecular components. This breakdown leads to a loss of performance in the final product and increases the rate of equipment wear. The characterization of these fluids determines the viability of a manufacturing process.
