Production of polyester filament involves melt spinning into partially oriented yam (POY), followed by drawing to enhance the bulk and mechanical properties. The industrial demand of increasing productivity is generally met by increasing POY melt spinning speeds, which is limited by increasing polymer chain orientation (and reducing residual drawability) in the POY produced at higher spinning speeds. Modification of the quench geometry during melt spinning is claimed to allow reduction of air drag and polymer chain orientation, permitting an increase in productivity during melt spinning into POY. We present a simple way for modeling the quenching of molten filaments under the modified (axial) air flow. Numerical simulations of the melt spinning are developed to demonstrate the influence of the quench geometry modification as we compare the process with the conventional cross-flow quench and the modified axial quench. We find that increasing quench air flow reduces the polymer chain orientation, in contrast to the well known effect in cross-flow quench. (c) 2010 Wiley Periodicals, Inc. J Appl Polym Sci 116: 2541-2547, 2010