Lowshear

Lowshear, often written as low shear in the literature, refers to conditions in which the rate of shear is small. In rheology and fluid mechanics, low shear describes a regime where deformation occurs at a low rate, so viscous resistance approaches the zero-shear value. It is typically contrasted with high-shear or shear-thinning regimes where viscosity depends strongly on the shear rate.

In many non-Newtonian fluids, viscosity changes with shear rate; at low shear, liquids often approach a Newtonian plateau and are described by the zero-shear viscosity. Measuring this value requires careful experimentation at very low shear rates and often extrapolation, since instrumentation limits or time-dependent structure (thixotropy) can affect readings near zero.

Lowshear is relevant in engineering and processing contexts. It is invoked in discussions of low-shear mixing, pumping, or extrusion to preserve delicate structures in emulsions, foams, polymers, and foods. In lubrication science, startup flows or narrow-gap configurations can exhibit low-shear behavior where the velocity gradient is small, influencing film formation and friction.

In biology and physiology, low shear stress environments influence how cells sense mechanical forces. Endothelial cells and other cell types respond to shear, with low-shear conditions associated with distinct signaling pathways and cellular behaviors. In meteorology, low wind shear describes small vertical changes in wind speed and direction, which can affect storm organization and development.

See also: zero-shear viscosity, shear rate, rheology, wind shear.