Role of transverse dimples in thermal-hydraulic performance of dimpled enhanced tubes

Rizwan Sabir, Muhammad Mahabat Khan, Muhammad Imran*, Nadeem Ahmed Sheikh, M. Irfan

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


This study numerically investigates the effects of transverse dimples in thermal and hydraulic performance improvement of Teardrop, Ellipsoidal-0o and Ellipsoidal-45o dimpled tubes under constant surface heat flux (q′′ = 10kW/m2) for turbulent Reynolds numbers (5000 ≤ Re ≤ 40,000). The number of dimples in the transverse direction (Star) are varied from 4 to 8 while maintaining the tube length to pitch (spacing between successive dimples) of 10 for each tube configuration. It is observed from Performance Evaluation Criteria (PEC) that Ellipsoidal-45o-Star 6 dimpled tube (Tube 7), as compared to the smooth tube, enhances the performance by 88.2% at Re = 5000 however, it reduces to 23.9% at Re = 20,000 and becomes negligible at Re = 40,000. The Ellipsoidal-45o dimples generate a non-symmetric wake and create a flow path between downstream dimples. As Star increases the flow momentum increases and a swirl flow pattern is generated and consequently enhances fluid-dimple interaction at low turbulent Re. On the contrary, Teardrop-Star 6 (Tube 2) and Ellipsoidal-0o-Star 6 (Tube 5) perform better at 20000 ≤ Re ≤ 40,000. Tube 5 produces distinct flow streams and enhances the fluid-surfaces interactions at higher Re. Therefore, it is recommended for high turbulent Re.

Original languageEnglish
Article number106435
Number of pages12
JournalInternational Communications in Heat and Mass Transfer
Early online date11 Oct 2022
Publication statusPublished - Dec 2022


  • Dimple tube
  • Fluid flow
  • Friction factor
  • Heat transfer augmentation
  • Star


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