Unsteady numerical simulations of the single-phase turbulent mixing between two channels connected by a narrow gap

Highlights: → Simulate the flow and turbulent mixing in geometries containing a narrow gap. → Unsteady numerical simulation with modify explicit algebraic Reynolds stress model. → The characteristics of the flow pulsation was correctly predicted. → The calculation results of turbulent mixing agrees well with the experiment. - Abstract: This paper focuses on the unsteady numerical simulation of the turbulent flow in two types of geometry containing a narrow gap with the explicit algebraic Reynolds stress model. The model was first validated through the comparison of simulation results inside a rectangular channel containing a cylinder and the corresponding experimental data. The structures of the oscillation were correctly reproduced. Simulation of turbulent mixing between circular channels connected by a narrow gap was carried out with the validated model. Because of the influence of the strong anisotropic turbulent flow in the gap region, the mixing rate was dramatically enhanced by the cyclic and almost periodic flow pulsation. The calculation results of the turbulent mixing rate showed good agreement with the experiment and the maximum error was less than 15%.