Rising bubbles in yield stress materials

We present an experimental investigation of bubbles rising in elasto-viscoplastic media. The effects of medium rheology and bubble size on the bubble velocity and shape are investigated. In addition, a discussion regarding the influence of the stress history on the bubble path is presented. Experimental tests are performed using yield stress materials which also present elastic behavior. Despite the difficulty in determining the relative importance of the different forces that are present in this flow, the results obtained illustrate the effect of yield stress, inertia, elasticity, and buoyancy on the dynamics and shape of the bubble. (C) 2017 The Society of Rheology.