In the processing of short fiber reinforced composite materials, it is very important to predict and control the fiber orientation state during flow. In this study, a rheological analysis on the fiber suspensions in Newtonian media has been performed to get more about the behavior of fiber suspensions. To do this, the fiber-fiber interaction coefficient was considered as a function of orientation state and average interfiber spacing, where the modified Doi-Edwards approach was used to calculate the spacing. As an example, the axisymmetric extrudate swell problem was applied and the results were compared with those from a previous paper by authors. The numerical results for two-dimensional flow and three-dimensional orientation field gave good agreement with experimental results. Since the fiber-fiber interaction coefficient is an important parameter and depends strongly on fiber orientation state, for a semiconcentrated fiber suspension, a method that regards the fiber-fiber interaction coefficient as a function of interfiber spacing and fiber orientation state enables more realistic analysis.