In this study, fluid flow driven by a combination of electromagnetic force, buoyancy force, are drag force, and surface tension gradient is numerically analyzed for a partially or fully penetrated weld pool in stationary gas tungsten are welding (GTAW). Irregular shape of the weld pool and the moving liquid-solid interface is handled by a boundary-fitted-coordinates technique. Surface tension on the top and the bottom free surfaces of the weld pool is found to play a critical role in determining the flow pattern in the weld pool. The calculated GTA weld bead geometry compares favorably with experimental results. (C) 2000 Elsevier Science Ltd. All rights reserved.