The main objective of this work is to simulate the axisymmetric and flat sheet extrudate in the extrusion process. A series of extrudate swell measurements for HDPE melts are carried out using an optical micrometer attached to the capillary rheometer, in order to study the effect of different die characteristics, temperature (isothermal and non-isothermal), and flow rate on extrudate dimensions. The polymer extrudate swell phenomenon is studied to understand the effects of parameters such as past deformation history (memory effects), die design characteristics, viscoelastic characteristics and process conditions. Accurate prediction of extrudate swell is very crucial in applications such as blow molding, extrusion and fiber spinning. The integral K-BKZ constitutive model is used for a high molecular weight HDPE and the simulated swell results were further compared with experimental observations. It was found that the integral K-BKZ model predicts well the experimental measurements provided that reliable rheological data are available.