Numerical simulation of three-way drag reduction based on shear thinning model
In order to study the drag reduction effect of adding surfactants on local components of heating pipelines,a three-way component model is selected,and CFD software is used to simulate the flow of pure water and CTAC/NaSal solution in the pipe under varying Reynolds numbers.The reliability of the Carreau-Bird model is verified by grid independence and comparison of drag reduction laws.The laws of drag reduction rate,flow velocity distribution,and changes in turbulent kinetic energy are emphatically analyzed,and the Ω criterion and Q criterion are used to further analyze the changes in the three-way vortex structure.The results demonstrate that,in comparison with a straight pipe,adding a CTAC solution in the tee results in a smaller drag reduction effect.Still,the maximum drag reduction rate is reached at a small Reynolds number.The addition of CTAC solution increases the flow velocity in the main pipe and alters the flow velocity distribution with the tee,leading to a reduction in the low-speed flow area and an increase in the high-speed flow area.This promotes laminar fluidization of the turbulent flow at the outlet.Simultaneously,it diminishes vorticity near the wall while augmenting vorticity in the central region of the vortex.
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