Minor losses in fluid systems refer to pressure decreases due to which of the following?

Minor losses in fluid systems are specifically associated with disruptions in the flow due to fittings and components within the piping system that do not maintain a constant flow area. This includes elements such as valves, tees, elbows, and other connections that introduce additional resistance to flow. As fluid navigates these bends or changes, turbulence increases, leading to localized energy losses manifested as pressure drops, which are categorized as minor losses.

Understanding minor losses is crucial in fluid mechanics because, although they may seem small compared to major losses (like those from straight pipe lengths), they can significantly impact the overall efficiency and performance of a fluid system. They are typically calculated using loss coefficients that quantify the amount of energy lost due to these fittings, highlighting their influence on overall system behavior.

The other options focus on factors that either do not pertain to the concept of minor losses or describe conditions that contribute to major losses rather than minor losses within a fluid system. For instance, fully developed turbulence in straight pipes maintains flow characteristics that do not introduce significant localized losses, thus differentiating those scenarios from the concerns addressed by minor loss calculations.