Stiffer alginate gels deposit more efficiently in microchannel flows
| Autor: | Smith, Barrett T, Hashmi, Sara M |
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| Rok vydání: | 2024 |
| Předmět: | |
| Druh dokumentu: | Working Paper |
| Popis: | The behavior of crosslinking polymer solutions as they transition from liquid-like to solid-like material in flow determines success or failure in several applications, from 3D printing to oil recovery in the earth's subsurface, to a wide variety of biological flows. Dilute polymer solutions flow easily, while concentrated polymers or crosslinked polymer gels can clog pores, nozzles, or channels. We have recently uncovered and described a third regime of flow dynamics in polymers that occurs when crosslinking happens during flow: persistent intermittency. When a dilute alginate solution meets calcium at a Y-shaped microfluidic junction, a persistent and regular pattern of gel deposition and ablation emerges when driven at a constant volumetric flow rate. Chemical concentrations and flow rate control both the deposition process and critical shear stress required to ablate the adhered gel. In this work, we provide an analytical framework to quantitatively describe the intermittent behavior as resulting from diffusively driven deposition in a high Peclet number flow, where convection dominates. Fitting the experimental data to the model allows estimation of the deposition efficiency and \textit{in situ} swelling ratios. Ablation occurs when applied shear stresses overcome either the adhesive energy of the gel or its yield stress. By correlating the results of the analytical analysis with bulk rheology measurements, we find that deposition efficiency increases with the stiffness of the gel formed in flow. Softer gels withstand higher shear stresses before ablation. Both deposition efficiency and gel stiffness increase in flow conditions nearing complete clogging. Comment: 32 pages, 6 figures |
| Databáze: | arXiv |
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