Constructal ducts with wrinkled entrances

This paper reports an increase in the heat transfer rate density by using wrinkled entrance regions in ducts with laminar flow. The heat transfer rate density is increased by taking advantage of the presence of relative isothermal fluid in the entrance regions. In order to stimulate a more complete thermal interaction between walls and fluid, the square entrances are wrinkled on the perimeter, at the one-third and the two-third positions. The new structure has two degrees of freedom. The fluid flow through the ducts is forced by the imposed pressure difference along the duct. Numerical simulations document the effects of the dimensionless pressure drop on the optimized configurations, and show a 15% enhancement in heat transfer rate density.