Effect of the turbulent contribution of the interfacial momentum transfer on the bubbles dynamics and void fraction distribution in vertical bubbly jets

A new formulation of the interfacial momentum transfer in two-fluid model for bubbly flows is presented and implemented in a CFD code. The main feature of the interfacial momentum closure lies in an explicit formulation of the turbulent contribution of the added mass force. The two-fluid model with the proposed closure of the momentum interfacial transfer is used to predict vertical bubbly jets. The numerical results show that the turbulent contribution of the added mass force greatly affects the dynamics of the bubbles and the gas distribution. The turbulent contribution of the added mass force has two components: a non-linear turbulent term and a convective acceleration associated to the drift velocity. Each of these turbulent terms can oppose the gravity effect. The simultaneous effects of the two turbulent terms provide an explanation to the deceleration of the bubbles as well as the negative relative velocity reported in the experimental data obtained in vertical bubbly jets. The improvements of the slip velocity prediction appear to have a great effect on the prediction of the lateral void fraction distribution. (C) 2019 Elsevier Ltd. All rights reserved.