A Particle-Center-Averaged Two-Fluid Model for Wall-Bounded Bubbly Flows

The accurate prediction of void fraction profiles near solid walls using the two-fluid model is still an unresolved issue. These profiles result from the combination of two factors: a) forces acting on the bubbles, and, b) geometric constraints imposed by their shape. We propose herein a two-fluid model that involves a particle-center-averaging procedure for the disperse phase, and a reinterpretation and postprocessing of the results obtained. This center-averaged approach averages the disperse phase (bubbles) based on a particle center indicator function, while using the standard phase indicator averaging for the continuous phase (liquid). The solution fields obtained are then postprocessed to introduce the geometry of the bubbles in order to recover the values that should be representative of measured fields. The key idea here is to separate the geometric aspect from the dynamic aspect of the problem into two independent, successive steps. The new model may be easily incorporated into existing two-fluid model codes. Results obtained with the new model showing agreement with experimental data (Moursali et al, 1995) are also presented.Copyright © 2002 by ASME