RST model for turbulent flow and heat transfer mechanism in an outward convex corrugated tube

• Reynolds stress transport model is used to simulate the complex flows.
• RST model for wavy-wall-bounded turbulent flow is validated by DNS results.
• Flow and heat transfer characteristics in an outward corrugated tube are studied.
• Significant heat transfer enhancement in outward corrugated tube flow is obtained.

The flow and heat transfer mechanism in an outward convex corrugated tube has been investigated through numerical simulations based on the Reynolds stress transport (RST) model. In this paper, the predictive capability and reliability of the RST model for turbulent flow in a tube with wavy wall is first examined. We perform a comparison between the results of RST modeling and the existing direct numerical simulation (DNS) by Maaß and Schumann (1996). The numerical results, including velocity and pressure coefficients for different profiles, between RST and DNS match well. On this basis, the RST model is considered to be more accurate than other Reynolds-averaged Navier–Stokes (RANS) models and is applied to research the detailed flow and heat transfer characteristics in corrugated tubes. Detailed predictions of mean velocity, mean temperature and anisotropic Reynolds stress at different profiles in one corrugation are carried out. It is found that the corrugation structure greatly increases the velocity fluctuation intensity. In the transverse direction the velocity fluctuation intensity is larger than that in the streamwise direction.