A three-dimensional numerical model is used for a turbulent buoyant jet. The standard k-c model has been modified to focus on the buoyancy-production term. The usual and modified buoyancy production coefficients are used for comparisons with experimental data reported in the literature. Imported numerical results are obtained with the modified coefficient for the stack-exit velocities and temperatures. The effects of these parameters on flow characteristics are discussed. (C) 2000 Elsevier Science Ltd. All rights reserved.