Improvement in cooling using a sinusoidal wavy surface for a turbulent dual jet: a computational study

A jet is used in numerous industrial applications, such as cooling systems, environmental dischargers, small chip cooling, and automobile demister. The complex nature associated with a turbulent dual jet flowing over a sinusoidal wavy surface is computationally studied by using two-dimensional steady RANS equations. The offset ratio of 3 and the number of the cycle are kept at 7, and the Reynolds number is set to 15,000. The amplitude varies from 0.1 to 0.8. Four different low-Re turbulence models, namely, the shear-stress transport (SST) k-omega model, renormalisation group k-e model, realizable k-e model, and standard k-omega model, are used. Based on the experimental validation, the SST k-omega model is considered for the present computational study. It is found that the heat transfer is enhanced by 34.56% for the amplitude of 0.8 compared to a plane surface. A correlation is also developed for the average Nusselt number and the maximum pressure with amplitude. The local Nusselt number rises with amplitude close to the jet exit. The results also show that the location of the maximum pressure is shifted to the wall corner and the magnitude of the maximum pressure rises with the amplitude. The positions of the merge point, upper and lower vortex centres are obtained and compared with the reported results. The similarity profiles at the positions of crest and trough show the opposite trends. The outcomes of the present analysis can be used to improve design and applications of heating or cooling jets in automobile industries, material processing, electronics, metal, etc.