Effect of particle size on modulating turbulent intensity

Turbulence modulation is an important physical phenomenon in solid-liquid two-phase flows, including two co-effects of wake enhancement and resistance dissipation. This physical phenomenon is usually modelled in an integrated way by adding two corresponding source terms to the turbulent kinetic energy (TKE) transport equation. However, this modelling strategy may easily cause the problem of explicit interference between the two co-effects, while the influencing factors of turbulence modulation are also not fully reflected, affecting the prediction accuracy of turbulence intensity. A new composite modelling strategy for turbulence modulation in dilute solid-liquid two-phase flows is proposed in this article. In the Euler-Euler framework, the two co-effects of turbulence modulation are modelled in a separate way to avoid the explicit interference. The resistance dissipation term is independently added to the TKE transport equation as a TKE change rate, while the wake enhancement term is independently added to the eddy viscosity as a TKE increment. On this basis, the appropriate mathematical expressions are determined, the influencing factors of the two effects are considered individually to reflect the dynamic characteristics of particles as fully as possible, and the empirical coefficients are calibrated for the condition of dilute solid-liquid two-phase flows to improve the applicability to the flow medium. Four typical flow cases are tested, and it is demonstrated that the new composite modelling strategy can better reflect the modulation of particles on the TKE of liquids, thereby providing higher-precision simulation results without significant increase in computational cost for dilute solid-liquid two-phase flows.