Abstract: A numerical method to solve the diffusion equation in configuration space for the distribution function of dumbbell models is described and the rheo-logical propcrli.cs of several models are calctilaled by using the method. This method is combined with the boundary clement method for solving the conservation equations in fluid dynamics in general cases. It is possible to use a molecular model which has no relevant constitutive equation to lake the place of the constitutive equation in continuum mechanics fo...