In a fluid piping system, which design change reduces flow resistance?

In a fluid piping system, which design change reduces flow resistance?

• A. A smoother interior surface reduces resistance
• B. More curves and elbows reduce resistance
• C. A larger pipe diameter increases resistance
• D. Higher viscosity reduces resistance

Answer: (A)

Flow resistance in a pipe is mainly due to friction between the fluid and the pipe walls. A smoother interior surface cuts down roughness, which reduces shear stress at the wall and lowers the friction factor. With less friction, the fluid can move more easily for the same pressure difference, so overall resistance is reduced. Curves and elbows create additional energy losses as the flow changes direction and stirs up turbulence, so they tend to increase resistance rather than lower it. Increasing pipe diameter generally lowers resistance by reducing flow velocity and friction, not increasing it. Higher viscosity makes it harder for the fluid to flow, increasing resistance instead of reducing it.

Flow resistance in a pipe is mainly due to friction between the fluid and the pipe walls. A smoother interior surface cuts down roughness, which reduces shear stress at the wall and lowers the friction factor. With less friction, the fluid can move more easily for the same pressure difference, so overall resistance is reduced.

Curves and elbows create additional energy losses as the flow changes direction and stirs up turbulence, so they tend to increase resistance rather than lower it. Increasing pipe diameter generally lowers resistance by reducing flow velocity and friction, not increasing it. Higher viscosity makes it harder for the fluid to flow, increasing resistance instead of reducing it.