[P2-65] Bubble dynamics of foam flow around an obstacle
Foams are one of the rare examples of simple yield stress fluids. Formed of bubbles embedded in liquid they are often studied in the context of jamming [1]. Foam flow is interesting not only because the start-up requires a dynamical unjamming transition (yielding), but also due to novel technological applications related to forming technologies [2].
Here, we study a foam flow through a 2D Hele-Shaw shell with an obstacle, forming a constriction. For this purpose, we use bubble scale dynamics model (the Durian bubble model), which we extend with the appropriate descriptions for the boundary effects coming from the walls and the top and bottom plates. We observe a negative wake behind the obstacle, analogous to the one observed in gas bubble motion in a viscoelastic medium. There, the medium is succesfully described by an Oldroyd-B model. This suggests that in the present conditions, the foam acts as a typical viscoelastic fluid, rather than the expected elastoviscoplasticity [3]. We compare the simulations data against experiments, foam intruder experiments, where we find a similar flow pattern. We find a reasonable agreement in the flow dynamics and the overshoots between the experimental data and the bubble model. Finally, we identify a viscoelastic timescale, which determines the magnitude of the velocity overshoot.
[1] G. Katgert, B. P. Tighe, M. van Hecke, Soft Matter 9, 9739 (2013).
[2] A. M. Al-Qararah, T. Hjelt, A. Koponen, A. Harlin, J. A. Ketoja, Colloids Surf. A 467, 97 (2015).
[3] S. Bénito, C. -H. Bruneau, T. Colin, C. Gay, F. Molino, Eur. Phys. J. E 25, 225 (2008)
Here, we study a foam flow through a 2D Hele-Shaw shell with an obstacle, forming a constriction. For this purpose, we use bubble scale dynamics model (the Durian bubble model), which we extend with the appropriate descriptions for the boundary effects coming from the walls and the top and bottom plates. We observe a negative wake behind the obstacle, analogous to the one observed in gas bubble motion in a viscoelastic medium. There, the medium is succesfully described by an Oldroyd-B model. This suggests that in the present conditions, the foam acts as a typical viscoelastic fluid, rather than the expected elastoviscoplasticity [3]. We compare the simulations data against experiments, foam intruder experiments, where we find a similar flow pattern. We find a reasonable agreement in the flow dynamics and the overshoots between the experimental data and the bubble model. Finally, we identify a viscoelastic timescale, which determines the magnitude of the velocity overshoot.
[1] G. Katgert, B. P. Tighe, M. van Hecke, Soft Matter 9, 9739 (2013).
[2] A. M. Al-Qararah, T. Hjelt, A. Koponen, A. Harlin, J. A. Ketoja, Colloids Surf. A 467, 97 (2015).
[3] S. Bénito, C. -H. Bruneau, T. Colin, C. Gay, F. Molino, Eur. Phys. J. E 25, 225 (2008)