Drag coefficient

About: Drag coefficient is a research topic. Over the lifetime, 14471 publications have been published within this topic receiving 303196 citations. The topic is also known as: drag factor.

CFD Simulation of Inlet Design Effect on Deoiling Hydrocyclone Separation Efficiency

Abstract: An Eulerian-Eulerian three-dimensional CFD model was developed to study the effect of different inlet designs on deoiling hydrocyclone separation efficiency. Reynolds averaged Navier Stokes and continuity equations were applied to solve steady turbulent flow through the cyclone with the Reynolds stress model. In addition, the modified drag correlation for liquid-liquid emulsion with respect to the Reynolds number range and viscosity ratio of two phases was used and the simulation results were compared with those predicted by the Schiller-Naumann correlation. Pressure profile, tangential and axial velocities and separation efficiency of the deoiling hydrocyclone were calculated for four different inlet designs and compared with the standard design. The simulation results for the standard design demonstrate an acceptable agreement with reported experimental data. The results show that all new four inlet designs offer higher efficiencies compared to the standard design. The difference between the efficiency of the LLHC, of the new inlets and the standard design can be improved by increasing the inlet velocity. Furthermore, the simulations show that the separation efficiency can be improved by about 10 % when using a helical form of inlet.

Variation of the Sectional Drag Coefficient of a Group of Buildings with Packing Density

Abstract: Reynolds-averaged Navier–Stokes (RANS) simulations of turbulent flow over groups of buildings with different packing densities are reported. The results for a selected packing density are compared with direct numerical simulations (DNS) previously validated against wind-tunnel data. The present study is focused on average properties of the flow, especially on the drag coefficients, and is a first attempt to provide information on these parameters (their values are not generally known) for a range of packing densities, for a given staggered arrangement of cubes using RANS methods. However, some of the limitations of RANS have come to light. Hence, it is recommended that such simulations are ‘calibrated’ against experimental or DNS data, as is done here.

The drag coefficient for a spherical bubble in a uniform streaming flow

Abstract: The drag coefficient CD=48/R for a spherical bubble in a uniform streaming flow at high Reynolds number, which was first obtained via a dissipation method by Levich [Zh. Eksp. Teor. Fiz. 19, 18 (1949)], is rederived here by direct integration of the normal stress over the bubble surface. The present study also shows that the drag coefficient up to O(R−1) depends only on the O(1) vorticity distribution right on the bubble surface, and is independent of the vorticity distribution in the fluid. Therefore the drag coefficient up to O(R−1) is completely determined by the irrotational flow solution, which is perfectly consistent with the dissipation method.