Volume flow is calculated as cross-sectional area times which velocity?

Volume flow is calculated as cross-sectional area times which velocity?

• A. Peak velocity
• B. Mean velocity
• C. Volume flow rate
• D. Minimum velocity

Answer: (B)

Volumetric flow is the amount of fluid passing through a cross-section per unit time, and it comes from averaging the velocity across the whole area. The total flow is the integral of v over the cross-section, Q = ∫_A v dA, which can be written as Q = A × v̄ when you use the mean (average) velocity v̄ across that area. Using the average velocity correctly accounts for how fast fluid moves at every point on the cross-section. If you used the peak velocity, you’d overestimate because not all parts of the cross-section move that fast; using the minimum would underestimate. The term “volume flow rate” is a rate, not a velocity. So the velocity to multiply by the area is the mean velocity across the cross-section.

Volumetric flow is the amount of fluid passing through a cross-section per unit time, and it comes from averaging the velocity across the whole area. The total flow is the integral of v over the cross-section, Q = ∫_A v dA, which can be written as Q = A × v̄ when you use the mean (average) velocity v̄ across that area. Using the average velocity correctly accounts for how fast fluid moves at every point on the cross-section.

If you used the peak velocity, you’d overestimate because not all parts of the cross-section move that fast; using the minimum would underestimate. The term “volume flow rate” is a rate, not a velocity. So the velocity to multiply by the area is the mean velocity across the cross-section.