A computational fluid dynamics (CFD) code, based on direct numerical simulation (DNS) and method of lines (MOL) approach previously developed for the prediction of transient turbulent, incompressible, confined non-isothermal flows with constant wall temperature was applied to the prediction of turbulent flow and temperature fields in flows dominated by forced convection in circular tubes with strong heating. The code was parallelized in order to meet the high grid resolutions required by DNS of turbulent flows. Predictive accuracy of the code was assessed by validating its steady state predictions against measurements and numerical results available in the literature. Favorable comparisons obtained reveal that the code provides an efficient algorithm for DNS of non-isothermal turbulent flows. (c) 2005 Elsevier SAS. All rights reserved.