A considerable amount of work has been done in the past to improve the solution methodology using the two-fluid model in the near-wall region. This includes the works of Larrateguy et al. [1], and Moraga et al. [2], based on a multi-scale bubble-center averaging technique. However one shortcoming is that the primitive variables must be recovered from the bubble-center averaged variables. This makes it difficult to implement it in a commercial CFD code. The current research focuses on an engineering approach to overcome this issue. A multi-scale near-wall averaging technique is proposed which separates the effects of bubble dynamics from its geometry in this region.
In addition, the averaged volume fraction profile makes the CFD approach consistent with the modified logarithmic law of Marie et al. [3]. A step function volume fraction distribution was assumed in the near-wall region while developing the theory. However, the volume fraction prediction obtained from CFD calculations is not uniform in this region. The proposed near-wall averaging technique resolves this issue and makes the CFD implementation of the modified wall function approach consistent with the theory of Marie et al. [3].
