“…Firth and Meyer [31] conducted an experimental study of the Stanton number and pressure drop performances of four different types of artificially roughened walls. They showed the statistical data for square transverse ribbed, helically ribbed, trapezoidal transverse ribbed, and three-dimensional walls for comparison, as shown in Hosni et al [33] presented the effect of truncated cone roughness elements on the local St and f and compared the experimental data with previously reported results obtained in the same test facility under similar flow conditions. Wu and Cooper [34] explored the heat transfer and pressure drop of an SAC with hemispherical indentations as roughness elements on a heated plate.…”