Three-dimensional flow structures in X-shaped junctions: effect of the Reynolds number and crossing angle

GOMBA J. M.; AURADOU H.; CORREA, P. G.; CACHILE M.; MAC INTYRE J. R.; HULIN J. P.

PHYSICS OF FLUIDS

AMER INST PHYSICS

Lugar: New York; Año: 2019 vol. 31

1070-6631

We study numerically the three-dimensional (3D) dynamics of two facing flows in anX-shaped junction of two circular channels crossing at an angle . The distributionof the fluids in the junction and in the outlet channels is determined as a function of and the Reynolds number Re. Our goal is to describe the different flow regimes inthe junction and their dependence on and Re. We also explore to which extent 2Dsimulations are able to describe the flow within a 3D geometry. In the 3D case, atlarge Re0s (& 50) and 0s (& 60), axial vorticity (i.e. parallel to the outlet axis) ofmagnitude increasing both with and Re develops in the outlet channels a structurethat cannot be reproduced by 2D numerical simulations. At lower angles ( . 60),instead, a mean vorticity component perpendicular to the junction plane is present:both its magnitude and the number of the corresponding vortices (i.e. recirculationzones) increase as decreases. These vortices appear in both 2D and 3D simulations,but at different threshold values of and Re. At very low Re0s (. 5) and 0s ( 15),the flow structure in 3D simulations is nearly two-dimensional but its quantitativecharacteristics differ from 2D simulations. As Re increases, this two-dimensionalitydisappears, while vortices due to flow separation appear in the outlet channels.