Fluid flow in an artificial model of a collecting lymphatic

Fluid flows in vascular networks are among the most effective way to transport matter and information for life. One striking example of swift and versatile transport is the lymphatic system in which lymph is transported across the whole body of mammals against intricate changes of pressures. In the collecting lymphatics, lymph is transported via vessel contractions combined with valve leaflets that ensure unidirectional transport. The nature of the active contractions, the multi-scale and multi-physics of the system make it challenging to model. Numerical simulations have brought many answers to these limitations. Yet, questions on the propagation of the vessel contractions along the lymphatic network remain difficult to answer.

Here, we study experimentally fluid transport in an upscaled model of a collecting lymphatic. We finely control the amplitude, the wavelength and the speed of the contraction wave, and the structure of the collecting lymphatic. Our results suggest that the presence of valve leaflets not only increases the flow rate, but also enables efficient transport for low speeds and for a limited number of actuation points. Overall, our work opens the way to systematic experimental studies of fluid transport in actuated channels.