جستجوی مقالات مرتبط با کلیدواژه « rotating circular cylinder » در نشریات گروه « مکانیک »

In the current study, the non-Newtonian flow over a cylinder is simulated using the lattice Boltzmann method. Two-dimensional unsteady flow at Re=100 and Pr=20 for different non-Newtonian power-law indices (0.4≤n≤1.8) and rotational ratios (0≤β≤3) is investigated. The effects of dimensionless rotational ratio and the power–law index on the vorticity contour, isotherm contour, local Nusselt number, average Nusselt number, periodic average Nusselt number and periodic-surface average Nusselt number are studied in detail. The results show that the fluid behavior changes from Newtonian to shear-thickening, the isotherms contour become elongated and wide, while the change in the liquid behavior from Newtonian to shear-thinning shows the reverse influence on the isotherm patterns. As dimensionless rotational ratio increases, the fluid and the thermal fields become steady. This behavior occurs in both Newtonian and non-Newtonian fluids. It is found that the increment of the shear-thinning and shear thickening of the fluid leads to the increase and decrease of heat transfer rate of circular cylinder surface, respectively. Results also show that the heat transfer rate of circular cylinder surface decreases with increasing of dimensionless rotational ratio.

In this study, unsteady flow around a rotating circular cylinder is investigated using Large Eddy Simulation method. The rotation rate varies between 0 and 2. Variation of the mean drag and lift coefficients, and the wake structure for different Reynolds numbers are studied. It was found that by increasing the rotation rate, the mean drag coefficient decreases and the mean lift coefficient increases. Length of the vortices behind the cylinder is also increased by increasing the rotation rate and by growing of Reynolds number. The results are compared with the other numerical simulation results and are also compared with the published experimental results.

In this study, the characteristics of the wake around a rotating circular cylinder have been investigated experimentally. To this end, a cylinder with a circular cross-section of Plexiglas with the length of 400 mm and a diameter of 20 mm have been tested in the wind tunnel. Using existing methods, the characteristics of the wake and the drag coefficients of the model in different cases have been investigated. In order to measure mean velocity profile and turbulence intensity, hot-wire anemometry has been used. The experiments carried out on the rotating cylinder indicates that the rotation of the cylinder causes significant changes in mean velocity profile. The rotation of the cylinder causes increase in the velocity in the vortex and decrease in the velocity of the wake. The variations become more and more by increase in rotational speed. Also, the results show that by increasing the rotation speed, the turbulence intensity in the wake increases. It is found that by increasing the rotational speed, the parameters of drag coefficient and velocity defect reduce.