Experimental and numerical investigation of flow structure in a cylindrical corrugated channel

In this paper, details of the flow characteristics in a duct with circular corrugated channel mounted on walls were investigated both experimentally and numerically. In this research, in order to study the flow behaviors of corrugated ducts, the Particle Image Velocimetry (PIV) technique was used for obtaining extensive information. From this point of view, present experimental work, using the PIV method has been provided significant data about flow in corrugated channels. The aspect ratio of the investigated channel, a/R is selected as 1. The flow characteristics are studied as a function of four different Reynolds numbers, such as Re=2000, 3000, 4000 and 5000. Generally, the target of this comprehensive work is to investigate the flow characteristics and hydrodynamics in the circular corrugated channels in terms of instantaneous and time-averaged flow data such as velocity, streamline, turbulent kinetic energy, Reynolds shear stress and vorticity in the measurement plane. The findings have suggested that the corrugated channel have helped to improve both transporting energy and momentum transfer; hence, heat transfer rate was enhanced. The turbulence occurred in the corrugated channel with the aid of a sharp corner is the dominant factor for developing the entrainment between wake and core flows. Furthermore, in the presence of both negative pressure gradient and kinetic energy along the direction of flow, the vortices are readily mounded in cavity zones. Fluid flow can explain the phenomena of augmentations in heat transfer conveniently. At low Reynolds numbers, available cavities can cause increments in both heat transfer area and flow turbulence. On the contrary, at high Reynolds numbers, the secondary flow enables agitating hot and cold fluids in cavities besides enhanced turbulence in ribs region. In the separated shear layer zone, the entity of large coherent vortices and cyclical processes like discontinuous subtraction of the recirculation region into the core flow zone are demonstrated by instantaneous flow properties. The experimental measurements have been performed in the side view plane of a model which has the same geometry have been validated by computations. The comparative data have been showed that the distribution of velocity profile changed periodically and indicated good agreement between simulations and experimental results.