According to Poiseuille's equation, what will happen to flow if pressure difference increases?

• A. Flow will increase
• B. Flow will stagnate
• C. Flow will become pulsatile
• D. Flow velocity will decrease

Answer: (A)

Poiseuille’s law shows that the amount of fluid that flows through a long, straight pipe in a given time (the flow rate) is directly driven by the pressure difference across the ends of the pipe. The relationship is Q = (π ΔP r^4) / (8 μ L). So, if the pressure difference increases while the radius, fluid viscosity, and pipe length stay the same, more fluid is pushed through per unit time, meaning the flow rate rises in proportion to ΔP. Since flow velocity v = Q / A (where A is the cross-sectional area), the velocity also increases for a constant pipe radius. Poiseuille’s equation describes steady, laminar flow, so phenomena like pulsatile flow would require time-varying pressures or other conditions not captured by this formula.