The area-velocity relation is primarily applicable to incompressible flow, meaning it assumes constant density, which does not hold true for real gases. The continuity equation is also limited to incompressible fluids, making it unsuitable for gases where density varies. The discussion highlights that the relation is derived under isentropic flow assumptions, raising concerns about its accuracy for experimental applications. Mach number (M) is introduced as a key variable in understanding the equation's context. Overall, while the area-velocity relation can provide useful insights, its limitations for compressible flow must be acknowledged.
