view:41896 Last Update: 2021-9-11
Introducing the Sliding-Wall Concept for Heat Transfer Augmentation: the Case of Flow over Square Cylinder at Incidence
The “sliding-wall concept” has been introduced for the case of convective heat transfer past a square cylinder with an angle of incidence. Based on this concept, all walls of the cylinder tangentially move at a constant speed. This idea is denominated by the “sliding-wall concept”, which can be constructed using a strip that is rolled around the body and moves at a constant speed. The finite-volume method is employed to numerically solve the governing equations using the OpenFOAM codes. Two critical wall velocities are computed, and it is found that the flow field is transient at velocities less than the first critical speed, and the separated vortices completely vanish beyond the second critical speed. It is obtained that by increasing the wall velocity up to 22 times the upstream velocity, a high mean Nusselt number of 40, and a mean lift coefficient of −40 can be achieved. It is found that at velocities greater than the second critical wall velocity, a part of the fluid that is affected by the hot body is confined to the areas near the cylinder. This flow pattern is called the “hotspot motion”. It is expected that the new observed trends can be extended to flows over other bluff bodies.