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The container (layer I and layer V) are acted on by viscous frictional forces between theįluid and the inner surface of the container’s wall. If the fluid in the container has nonzero viscosity, then the layers in contact with the walls of The fluid is modeled asįlowing continuously without any such starting or stopping points. Such points would involve changes to the velocity of the flow. This is done to avoid the need to consider points at which flow starts or stops, as Parallel to the flow direction, no such boundaries are shown perpendicular to the flowĭirection. Instead, turbulence occurs when a critical Reynolds number (Re) is exceeded.It is important to appreciate that although we can now see definite boundaries to the flow

Therefore, as blood flow velocity increases in a blood vessel or across a heart valve, there is not a gradual increase in turbulence. Turbulence does not begin to occur until the velocity of flow becomes high enough that the flow lamina break apart. Turbulence increases the energy required to drive blood flow because turbulence increases the loss of energy in the form of friction, which generates heat. When this occurs, blood does not flow linearly and smoothly in adjacent layers, but instead the flow can be described as being chaotic.The Turbulent flow also occurs in large arteries at branch points, in diseased and narrowed (stenotic) arteries (see figure below). However, under conditions of high flow, particularly in the ascending aorta, laminar flow can be disrupted and become turbulent. Generally in the body, blood flow is laminar. One practical implication of parabolic, laminar flow is that when flow velocity is measured using a Doppler flowmeter, the velocity value represents the average velocity of a cross-section of the vessel, not the maximal velocity found in the center of the flow stream. This occurs in long, straight blood vessels, under steady flow conditions. The flow profile is parabolic once laminar flow is fully developed. The lowest velocity (V=0) is found along the vessel wall. The highest velocity (Vmax) is found in the center of the vessel. It is characterized by concentric layers of blood moving in parallel down the length of a blood vessel. Laminar flow is the normal condition for blood flow throughout most of the circulatory system. In turbulent flow should be greater than 4000 Application of laminar and turbulent flow Flow in blood vessel Laminar flow So that the reynolds number in laminar flow should be less than 2000 also we should know the reynolds number The flow is primarily determined by reynolds number: This ratio is called the Reynolds number. The flow regime depends mainly on the ratio of inertial forces to viscous forces in the fluid. Other plumes behave similarly in below figure The flow regime in the first case is said to be laminar, characterized by smooth streamlines and highly ordered motion, and turbulent in the second case, where it is characterized by velocity fluctuations and highly disordered motion. If you have been around smokers, you probably noticed that the cigarette smoke rises in a smooth plume for the first few centimeters and then starts fluctuating randomly in all directions as it continues its rise. The streak-line also fluctuates randomly with time.so where considerable mixing occurs, velocities are high. When the fluid is moving faster, get an irregular streak-line which blurs and spreads the dye out. This flow situation is called laminar flow so Where the fluid moves slowly in layers in a pipe, without much mixing among the layers. When the fluid is moving slowest, get a well-defined streak-line. 3 Application of laminar and turbulent flow.