A physical model was proposed to describe granular material drying in a semi-circular impinging stream dryer, and the multi-phase flow characteristics as well as the heat and mass transfer were numerically investigated. Specially, the influence of various factors (inlet air temperature, mass flow-rate ratio, initial moisture content etc.) on drying process was inspected. The results indicate that constant drying rate period does not exist in a semi-circular impinging stream dryer. Appropriate curvature radius, flow-rate ratio, air velocity and higher inlet air temperature should be chosen for improving the drying performance, and decreasing the energy consumption and operation cost. The numerical predictions were compared with the available experimental results, and they are in quite good agreement with each other. (C) 2003 Elsevier Science Ltd. All rights reserved.