This thesis aimed the numerical analysis of fluid field and mass transfer for turbulent flow in a 90°. The RNG version of k –? model was used for turbulence modeling. At first the continuity and momentum equations were solved for turbulent flow through a 3-D bend and flow field was obtained in different stations of the bend. Also, for validation of the results the predicted velocity profiles at 30°, 75° and the exit of the elbow stations were compared with the experimental data and showed good agreement. Then, by solving the component mass continuity equation for the naphthalene-air system, the mass transfer coefficient in the bend and the ratio of it to the mass transfer coefficient for fully developed flow in a straight pipe (Sh/Sh p ) in different stations of the bend were obtained. For all these cases the maximum of (Sh/Sh p ) was observed at a distance about one diameter downstream of the elbow and changes between 1.26 to 1.46. Also a correlation for predicting the maximum mass transfer coefficient was developed. This correlation is a function of Reynolds number, Schmidt number and curvature ratio and shows that only the curvature ratio has the significant effect on maximum of this ratio. These results showed that Sh/Sh p decreases about 20 percent as curvature ratio increases from 1.5 to 2.5. Results that obtained from numerical solution were in good agreement with the mass transfer coefficient obtained from the friction factor and by using the Chilton-Colborn analogy. Finally the numerical analysis results were compared with the experimental data for a naphthalene-air system and showed good agreement.
