What are the highest and lowest Reynolds number flows that can be accurately computed by a given numerical method?
This question has a variety of answers, and, as with most technical issues, the variety of answers arises from the assumptions involved in giving the answer. For present purposes, the Reynolds number R is defined as R=LU/ν, where L and U are characteristic length and velocity scales for a flow, and ν is the kinematic viscosity of the fluid. It will be recalled that the non dimensional Reynolds number is a measure of the importance of inertia to viscosity effects. At high Reynolds numbers a flow may become turbulent, exhibiting qualitatively different behavior. Generally, the most important limit to consider is that of high Reynolds numbers. This is the limit where computations might be used to predict the breakdown of a laminar flow into turbulence, or the lift and drag of a body that is dependent on where boundary layers separate from its surface. In these or other types of flow processes in which it is critical to correctly simulate the relative effect of viscous stresses on the flow
