Which flow has essentially constant velocity across the vessel and is found in large arteries?

Which flow has essentially constant velocity across the vessel and is found in large arteries?

• A. Plug flow
• B. Laminar flow
• C. Turbulent flow
• D. Disturbed flow

Answer: (A)

Flow across a vessel is described by the velocity profile across its cross-section. When the velocity is essentially the same at all points from wall to center, that is called plug flow. In large arteries, the diameter is big and the entering flow can move with little shear across the lumen, so the layers travel together rather than forming a steep gradient from center to wall. This flat, plug-like profile is why the flow is described as having essentially constant velocity across the vessel, especially during peak flow. In Doppler terms, plug flow gives a narrow spectral width because the velocities within the gate are nearly identical. In contrast, laminar flow has a parabolic profile with the fastest speed at the center and slower speeds toward the walls, producing a range of velocities within the sample volume. Turbulent flow is chaotic with many directions and a wide range of velocities, showing broad spectral broadening. Disturbed flow is irregular and transitional.

Flow across a vessel is described by the velocity profile across its cross-section. When the velocity is essentially the same at all points from wall to center, that is called plug flow. In large arteries, the diameter is big and the entering flow can move with little shear across the lumen, so the layers travel together rather than forming a steep gradient from center to wall. This flat, plug-like profile is why the flow is described as having essentially constant velocity across the vessel, especially during peak flow. In Doppler terms, plug flow gives a narrow spectral width because the velocities within the gate are nearly identical.

In contrast, laminar flow has a parabolic profile with the fastest speed at the center and slower speeds toward the walls, producing a range of velocities within the sample volume. Turbulent flow is chaotic with many directions and a wide range of velocities, showing broad spectral broadening. Disturbed flow is irregular and transitional.