Abstract: The spectral method, ie. Galerkin method and the pseudo-spectral method wereused to solve the diffusion equation of the distribution function in configurational space for amultibead-rod model and N-S equation respectively. The properties of the coherent structure ina plane mixing layer with rigid-rodlike polymer additives and the most probable orientations ofthe multibead rods were obtained simultaneously. The results indicate that adding polymer tothe Newtonian fluid will make flows have stronger vorticity...