Large Eddy Simulation of turbulent fluid mixing in double-tee junctions

Abstract

Double-Tee junctions serve as building blocks of pipe network systems and fluid mixing occurring in them is complex due to excessive eddying of flow. In this paper a LES model with pure advection was used on a double-Tee junction turbulent mixing phenomena problem. This kind of approach does not require the turbulent Schmidt number which is problem specific and needs to be calibrated with experimental data. When applying the LES-WALE turbulence model in conjunction with the pure advection transport of a scalar quantity on the double-Tee mixing problem it is achieved that the resolved turbulent flow field accurately transports the scalar when compared to experimental data from literature. This approach enables accurate mixing predictions in double-Tee junctions for the purpose of correcting simpler 1D numerical mixing models without the need of obtaining new experimental data since no turbulent Schmidt number calibration is needed. The approach can be applied to biological or chemical agent transport in a fluid and the model was tested and shown to be valid for a Reynolds number range of 20,000–400,000 on three different types of double-Tee junction configurations and five double-Tee distances with a constant inlet and outlet pipe diameter.

Keywords

• LES-WALE
• Large Eddy Simulation
• Turbulent mixing model
• Double-Tee junctions
• Schmidt number
• Pure advection