Heat transfer surfaces are often artificially roughened to enhance heat transfer. Repeated ribs are sometimes used for this purpose. Based on an extensive database, Ravigururajan and Bergles...

Heat transfer surfaces are often artificially roughened to enhance heat transfer. Repeated ribs are sometimes used for this purpose. Based on an extensive database, Ravigururajan and Bergles (1996) proposed the following correlations for the roughness types depicted in Figure P7.20, which is recommended by Manglik (2003):