How do friction losses through a pipe relate to the pipe’s diameter?

Friction losses in a pipe are influenced significantly by the pipe's diameter. When considering fluid dynamics, larger diameter pipes generally result in lower friction losses. This is because a larger diameter allows for a greater cross-sectional area for the fluid to flow, reducing the velocity required to maintain the same flow rate. According to the principles outlined in the Darcy-Weisbach equation and the Poiseuille equation, friction loss is inversely related to the diameter of the pipe—meaning the larger the diameter, the lower the friction loss will be.

In larger pipes, the increased space allows for smoother flow and less contact between the fluid and the pipe walls, which reduces turbulence and thereby decreases the energy loss due to friction. Consequently, as the diameter of the pipe increases, the amount of energy lost to friction during water distribution decreases, making the correct choice about the relationship between pipe diameter and friction losses evident.