Abstract
We present a detailed study of the dynamics of soft liquid interfaces undergoing viscous stresses due to bulk flows generated by a momentum transfer from light to a turbid liquid. Using a continuous laser wave, light-induced flow is observed and analyzed through the deformability of very soft interfaces up to instability and jet formation. These dynamics are investigated experimentally and numerically below and above the interface instability threshold. Below instability, we show that the dynamics of the interface deformation at short timescales does not vary with the parameters of the laser excitation. We confirm that the mechanism responsible for the interface deformation is a nonlocal effect associated to the viscous stress induced by the bulk flow. Then, we characterize the jetting instability regarding the numerical velocity field within the jet, the jet radius and the fluid flow rate. A satisfying agreement is obtained when comparing quantitatively experimental results and numerical predictions. Our investigation illustrates how light can induce a bulk flow in a turbid liquid, such as a suspension, and how this flow can be used to deform an interface and produce well-controlled liquid jets.
1 More- Received 5 July 2019
- Accepted 28 January 2020
DOI:https://doi.org/10.1103/PhysRevFluids.5.024002
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