Abstract: A numerical investigation of surface heat transfer
characteristics of turbulent air flows in different parallel plate
grooved channels is performed using CFD code. The results are
obtained for Reynolds number ranging from 10,000 to 30,000 and for
arc-shaped and rectangular grooved channels. The influence of
different geometric parameters of dimples as well as the number of
them and the geometric and thermophysical properties of channel
walls are studied. It is found that there exists an optimum value for
depth of dimples in which the largest wall heat flux can be achieved.
Also, the results show a critical value for the ratio of wall thermal
conductivity to the one of fluid in which the dependence of wall heat
flux to this ratio almost vanishes. In most cases examined, heat
transfer enhancement is larger for arc-shaped grooved channels than
rectangular ones.
Abstract: Turbulent forced convection flow in a 2-dimensional channel over periodic grooves is numerically investigated. Finite volume method is used to study the effect of turbulence model. The range of Reynolds number varied from 10000 to 30000 for the ribheight to channel-height ratio (B/H) of 2. The downstream wall is heated by a uniform heat flux while the upstream wall is insulated. The investigation is analyzed with different types of nanoparticles such as SiO2, Al2O3, and ZnO, with water as a base fluid are used. The volume fraction is varied from 1% to 4% and the nanoparticle diameter is utilized between 20nm to 50nm. The results revealed 114% heat transfer enhancement compared to the water in a grooved channel by using SiO2 nanoparticle with volume fraction and nanoparticle diameter of 4% and 20nm respectively.
Abstract: In this work, we perform numerical simulation of fluid
mixing in a floor-grooved micro-channel with wavy sidewalls which
may impose perturbation on the helical flow induced by the slanted
grooves on the channel floor. The perturbation is caused by separation
vortices in the recesses of the wavy-walled channel as the Reynolds
number is large enough. The results show that the effects of the wavy
sidewalls of the present micromixer on the enhancement of fluid
mixing increase with the increase of Reynolds number. The degree of
mixing increases with the increase of the corrugation angle, until the
angle is greater than 45 degrees. Besides, the pumping pressure of the
micromixer increases with the increase of the corrugation angle
monotonically. Therefore, we would suggest setting the corrugation
angle of the wavy sidewalls to be 45 degrees.