A delayed detached eddy simulation model with low Reynolds number correction for transitional swirling flow in a multi-inlet vortex nanoprecipitation reactor

Abstract

The objective of the presented work is to verify a delayed detached eddy simulation (DDES) model for simulating transitional swirling flow in a micro-scale multi-inlet vortex reactor (MIVR). The DDES model is a k-w based turbulence model with a low Reynolds number correction applied to the standard k-w model such that the Reynolds-averaged Navier-Stokes (RANS) component of the DDES model is able to account for low Reynolds number flow. By limiting the dissipation rate in the k-equation, the large-eddy simulation (LES) part of the DDES model behaves similarly to a one-equation sub-grid model. The turbulent Reynolds number is redefined to represent both modeled and resolved turbulence level so that underestimation of the RANS length scale in the LES range can be reduced. Applying the DDES model to simulate both laminar and transitional flow in the micro-scale MIVR produces an accurate prediction of mean velocity and turbulent intensity compared with experimental data. It is demonstrated that the proposed DDES model is capable of simulating transitional flow in the complex geometry of the micro-scale MIVR. These simulation results also help to understand the flow and mixing patterns in the micro-scale MIVR and provide guidances to optimize the reactor for the application of producing functional nanoparticles.

Simulation of Continuous Phase Flow in Small‐Scale Vortex Devices: Model Applicability Assessment

“…Hence, using accurate models is critical for predicting the anisotropy and non-equilibrium effects. To date, the issues of CFD-based numerical simulation remain in the flow simulation process, including: (i) because of the complexity [12,13] it is necessary to determine the vortex flow characteristics and patterns; moreover, the global flow information is difficult to be measured precisely due to its small size (body diameter is around 6-100 mm); (ii) compared to large-scale vortex reactor/separators, extra lateral and normal divergence usually occurs, causing an increasing difficulty in numerical simulation [14]; (iii) for most investigations, however, the effect of transitional flow usually does not take into account in the simulation [15][16][17]; (iv) for SVR/Ss with variable designs and operating parameters, the generalizability of the numerical models has not been comprehensively evaluated based on techno-economic performances.…”