Bubbly flows are essential in many industrial and environmental applications and several methodologies have been employed to investigate the complex phenomena involved. In the present book Direct Numerical Simulations of bubble swarms in channel flow configuration are reported and several cases are presented. The focus is on the mutual interaction between fluid turbulence and bubble dynamics and the impact on the heat transfer in the two-phase mixture. This analysis concerns flow visualizations and quantitative statistical data regarding the fluid as well as the bubbles which can now be used as reference data for model developing and validation.