express Fluid motion A property of time. Mathematics of continuity expression Is ρ 1u1A1=ρ 2u2A2=constant, where ρ, u, A are respectively Fluid density , speed and in pipe Cross-sectional area , subscript 1,2 indicates different section 。 The essence of continuity is that mass conservation 。 Let function f be defined in a U (x0). If lim f (x) x → x0=f (x0), it is called f Continuous at point x0
