In laminar flows, velocity gradients are sufficiently mild so that the fluid can dynamically adjust to imposed shear stresses through molecular (viscous) forces. When imposed shear forces are too great for the fluid to adjust through molecular processes, the fluid is “torn” into largely coherent regions (turbulent eddies), which can rotate much like fluid “roller bearings” and thus relieve the shear forces caused by the imposed velocity differences. These turbulent eddies, in turn, undergo a chaotic sequence of events in which they are reduced in scale, until eventually a dimension is reached below which the laminar or molecular processes are sufficient to control the fluid response to the imposed shear forces.
KeywordsTurbulent Kinetic Energy Reynolds Stress Eddy Viscosity Reynolds Equation Turbulent Eddy
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