In this paper, the generalized vector composite formulas are proved by the mapping method of complex function, and a necessary and sufficient condition that can be used easily is proved too.

The seepage of CFRD joints is studied by using finite element calculation and complex variable function. The analytical equations of seepage quantity and gradient are deduced.

Haskind discussed the non-steady motions of small curved planing plate by using the theory of complex functions, and obtained the general expression of hydrodynamic forces.