What is Reynolds?

The term "Reynolds" is most commonly associated with Osborne Reynolds, a physicist and engineer. Without further context, it likely refers to the Reynolds number, a dimensionless quantity used in fluid mechanics to predict flow patterns in different fluid flow situations. It is the ratio of inertial forces to viscous forces and consequently quantifies the relative importance of these two types of forces for given flow conditions. It is commonly used to determine whether a flow will be laminar or turbulent. Reynolds also contributed to lubrication theory.