0 U ud(u/l δa(y/δ)0 u=a+by+cy BC:y=0=0 Q0 y=8u≈U u。0 a=0.b= C 2yy0≤y≤6(x) Uδδ10 0 (1 ) u u dy U U   = −  y  ( ) x u(y) x 2 u a by cy = + + 2 2 0, , - U U a b c   = = = 2 2 u y y 2 U   = − 0 ( )  y x  y u = = 0 0 0 u y    y u U =   BC: 0 ( / ) ( / ) =   = y y U u U    =0   w = y y u  