the pressure at any location reaches an absolute pressure equal to the saturated vapour pressure of the liquid

pressure becomes more than critical pressure

flow is increased

pressure is increased

comparing two identical equipments

designing models so that the result can be converted to prototypes

comparing similarity between design and actual equipment

hydraulic designs

ratio of inertial force to force due to viscosity

ratio of inertial force to force due to gravitation

ratio of inertial force to force due to surface tension

all the four ratios of inertial force to force due to viscosity, gravitation, sur-face tension, and elasticity