Investigation on influences of bubble location and momentum transfer direction on liquid turbulence modification for the dilute bubbly flow

It is very significant for the effective design and operation of bubbly equipments to understand deeply the liquid turbulence modulation mechanism by bubbles. In the present paper, detailed investigations on modulation of bubbles on the liquid turbulence, for the dilute bubbly flow with a low liquid-phase Reynolds number, were carried out with the developed Euler-Lagrange numerical method when bubbles always stayed in different turbulence layers for the horizontal and vertical channels, respectively. The velocity field of the liquid phase was solved with direct numerical simulation (DNS), and the bubble motion was followed with Newtonian motion equations. The present studies show that the liquid-phase turbulence modulation is tightly related to the bubble location and the momentum transfer direction between bubbles and liquid (i. e., the gravity direction); it should be noted that when bubbles are located in the turbulence buffer layer, the opposite phenomena happen to the liquid turbulence modulation by bubbles for the horizontal and vertical channels.