Revisiting RANS turbulence modelling for bubble-induced turbulence: Effects of surfactants

Recent experiments of dispersed bubbly flow (Ma et al., 2023) show that contamination of the carrier phase plays a considerable role in bubble-induced turbulence (BIT): although the bubbles rise slower with adding surfactants, the BIT increases. This trend, however, cannot be reproduced by any current BIT models in the framework of Euler-Euler Reynolds-averaged Navier-Stokes two-equation turbulence model, including the model proposed by Ma et al. (2017). The present work revisits this widely used model (Ma et al., 2017) as a representative, which considers the BIT with an additional source term in the k - and E (or w ) - equation, respectively. We have systematically investigated the reason why such a BIT model is unable to capture the BIT modulation caused by different degrees of contamination and discuss the new possibility for the prefactor in the source term of the E -equation that may improve the results.