Local resistance in a fluid power system typically occurs at which points?

Local resistance in a fluid power system is primarily caused by the disruptions in flow at specific points such as bends, valves, or expansions. These components alter the uniform flow of the fluid, leading to a decrease in velocity and an increase in pressure drop, which contributes to the overall resistance experienced by the fluid.

When fluid flows through bends, for instance, it experiences a change in direction, which can cause turbulence and energy losses. Similarly, valves, which are designed to control flow, create abrupt changes in pressure and velocity as they open and close, further contributing to local resistance. Expansions in the system can also create areas where the fluid decelerates, leading to energy loss as the fluid adjusts to the new diameter.

In contrast, while fluid heating can affect viscosity, and the entrance of the system can create some initial loss due to entrance effects, these do not represent local resistance in the same way as the interactions at bends, valves, or expansions. Straight pipes create a more consistent flow without the significant disruptions that cause local resistance, thus making them less relevant when discussing local points of resistance.