The twenty-seventh volume of the Thermophysics series is devoted to investigating heat transfer, hydrodynamics and flow mixing in gas-cooled fuel rod assemblies in longitudinal flow with a marked change in geometric characteristics of the cells along the assembly radius. The book presents data of the experimental and theoretical study of local heat transfer and hydrodynamics in assemblies of smooth and rough rods, spaced using honeycomb spacer grids. Alongside assemblies with spacer grids, consideration was given to assemblies with a wire winding. Extensive experimental data made it possible...