The pneumatic conveying dryer has been in general use for drying or expanding cut tobacco in the cigarette industry because of high heat-transfer efficiency. So it is an important matter to clarify the phenomenon of heat / mass transfer of cut tobacco in the pneumatic conveying dryer. Since the heat / mass transfer is influenced by the fluid dynamics of cut tobacco in the dryer, it should be a first step to clarify the fluid dynamics in the dryer. The Authors have tried to develop a numerical fluid simulation method for the fluid dynamics of cut tobacco in the pneumatic conveying dryer in order to predict the fluid dynamics, instead of an actual test in dryer. This numerical method is based on the gas-solid two-phase flow modeling that incorporates both gas phase (air with water vapor) and solid phase (cut tobacco). We also tried to solve the problems with consideration of actual shape of cut tobacco because the shape of cut tobacco is not spherical or uniform. Therefore using this method, we can realistically predict a momentum history of each cut tobacco in the pneumatic conveying dryer.