Fluid accelerates over a convex surface due to a reduction in cross-sectional area, which necessitates an increase in velocity to maintain flow rate. Once the fluid passes the obstruction, it decelerates back to its original velocity. The concept of flow attachment explains that as the area increases after the convex shape, the fluid tends to follow the contour of the surface. This behavior is influenced by the fluid's desire to fill any voids created by moving objects, resulting in a "sticking" effect. Understanding these dynamics is crucial for analyzing fluid behavior in various applications.