Most of the added mass closure relations for two-phase modeling are numerically obtained from simulations involving single bubble or precise networks of bubbles. Their applicability to systems with high void fraction is therefore questionable. In this presentation, we will present a semi-analytical model using solid harmonics to resolve the potential flow around a cloud of bubbles and around a bubble in the vicinity of an infinite wall. We will show that our model proposes some relations for added mass with regards to the void fraction and wall proximity. We will also compare our model to previously published relations and unify some discrepancies between them.