ANS:C - distortion

1. Irregularities in the Flow Path: Distortion can occur when the flow encounters irregularities or obstacles in its path. These irregularities can cause the flow to deviate from its intended path and lead to changes in velocity, pressure, and flow pattern.
2. Changes in Geometry: Alterations in the geometry of the flow path, such as sudden expansions or contractions, bends, or changes in cross-sectional area, can cause distortion in the flow. These changes can disrupt the smoothness and uniformity of the flow, leading to variations in velocity and pressure.
3. Turbulence: Turbulence is a form of fluid flow characterized by chaotic, irregular motion and the formation of eddies and vortices. Turbulence can cause significant distortion in the flow pattern, leading to fluctuations in velocity and pressure throughout the flow field.
4. Rotational Flow: Rotational flow, where the fluid particles rotate as they move through the flow field, can also introduce distortion. While rotational flow patterns are often observed in certain fluid systems (such as vortex flows), they can disrupt the uniformity of the flow and cause variations in flow properties.