SIMULATION OF VISCOELASTIC FLOWS USING BROWNIAN CONFIGURATION FIELDS

In this paper we present a new approach for calculating viscoelastic f lows. The polymer stress is not determined from a closed-form constitu tive equation, but from a microscopic model. In this description, we r eplace the collection of individual polymer molecules by an ensemble o f configuration fields, representing the internal degrees of freedom o f the polymers. Similar to the motion of real molecules, these configu ration fields are convected and deformed by the flow and are subjected to Brownian motion. We incorporated this field description in a finit e element calculation. An important advantage of our approach is that the difficulties associated with particle tracking of individual molec ules are circumvented. In order to validate our approach and to demons trate its robustness, we present the results for the start-up of plana r flow of an Oldroyd-B fluid past a cylinder between two parallel plat es. The results are very promising. We find excellent agreement betwee n the results of the configuration field formulation and those obtaine d using a closed-form constitutive equation. Moreover, the microscopic method appears to be more robust than the conventional macroscopic te chnique. (C) 1997 Elsevier Science B.V.