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The particle Reynolds number is important in determining the fall velocity of a particle. When the particle Reynolds number indicates laminar flow, Stokes' law can be used to calculate its fall velocity or settling velocity. When the particle Reynolds number indicates turbulent flow, a turbulent drag law must be constructed to model the ...
The main parameter characterizing transition is the Reynolds number. Transition is often described as a process proceeding through a series of stages. Transitional flow can refer to transition in either direction, that is laminar–turbulent transitional or turbulent–laminar transitional flow.
The dimensionless Reynolds number is an important parameter in the equations that describe whether fully developed flow conditions lead to laminar or turbulent flow. The Reynolds number is the ratio of the inertial force to the shearing force of the fluid: how fast the fluid is moving relative to how viscous it is, irrespective of the scale of ...
The chart plots Darcy–Weisbach friction factor against Reynolds number Re for a variety of relative roughnesses, the ratio of the mean height of roughness of the pipe to the pipe diameter or /. The Moody chart can be divided into two regimes of flow: laminar and turbulent .
Conceptually, the Reynolds number is the ratio between inertial forces and viscous forces. [6] Schlieren photograph showing the thermal convection plume rising from an ordinary candle in still air. The plume is initially laminar, but transition to turbulence occurs in the upper third of the image.
For turbulent flows near separation, 2.7. [17] The dividing line defining laminar-transitional and transitional-turbulent values is dependent on a number of factors so it is not always a definitive parameter for differentiating laminar, transitional, or turbulent boundary layers.
Dimensionless numbers (or characteristic numbers) have an important role in analyzing the behavior of fluids and their flow as well as in other transport phenomena. [1] They include the Reynolds and the Mach numbers, which describe as ratios the relative magnitude of fluid and physical system characteristics, such as density, viscosity, speed of sound, and flow speed.
In Poiseuille flow, for example, turbulence can first be sustained if the Reynolds number is larger than a critical value of about 2040; [25] moreover, the turbulence is generally interspersed with laminar flow until a larger Reynolds number of about 4000.