4) What is the Reynolds number- Give an equation but also an explanati.docx
- 1. 4) What is the Reynolds number? Give an equation but also an explanation of what is being compared. Give two situations where the Reynolds number is used Solution The Reynolds number (Re) is a dimensionless number related to fluid mechanics. It is among the most important attributes used for summarizing the forces acting on a fluid and, based on its value, the turbulence or lack of turbulence of a fluid is determined. The designation is named for Osborne Reynolds, who made many pioneering studies in fluid mechanics in the late 19th and early 20th centuries. The variations in the quantity are laid out on the X-axis of the Moody Chart, one of the more useful graphs in fluid mechanics. More specifically, the Reynolds number is defined as the ratio of inertial forces, which contribute to turbulence, to viscous forces, which act against turbulence, within a fluid. Put another way, the number describes how likely flow is to be laminar or turbulent for a given set of physical conditions. Laminar, or smooth, flow indicates that everything in the flow of a fluid is moving in the same direction and these internal flows do not affect one another. Turbulent flow, on the other hand, indicates that disruptions or eddies are created within the main flow. The most common example of laminar and turbulent flow can be found at a sink. When the water is first turned on and is not flowing very fast, it is clear. Most of the internal flows of the water do not interact with one another and move in the same direction; this is laminar flow and indicates a low Reynolds number. As the amount and speed of the water increases, it turns white. The internal flows begin to collide with one another in a turbulent flow, introducing air into the water stream. Another example of the concept is to imagine an object moving through a fluid. The faster the object moves, the denser the liquid, and the more time the object moves, the more likely the fluid flow is to be turbulent. The more viscous or sticky a fluid is, the greater the chance the fluid