{
  "id": "1508.00141",
  "version": "v1",
  "published": "2015-08-01T16:07:01.000Z",
  "updated": "2015-08-01T16:07:01.000Z",
  "title": "Effects of viscoelasticity on droplet dynamics and break-up in microfluidic T-Junctions: a lattice Boltzmann study",
  "authors": [
    "Anupam Gupta",
    "Mauro Sbragaglia"
  ],
  "comment": "16 pages, 14 figures",
  "categories": [
    "physics.flu-dyn",
    "cond-mat.soft"
  ],
  "abstract": "The effects of viscoelasticity on the dynamics and break-up of fluid threads in microfluidic T-junctions are investigated using numerical simulations of dilute polymer solutions at changing the Capillary number ($\\mbox {Ca}$), i.e. at changing the balance between the viscous forces and the surface tension at the interface, up to $\\mbox{Ca} \\approx 3 \\times 10^{-2}$. A Navier-Stokes (NS) description of the solvent based on the lattice Boltzmann models (LBM) is here coupled to constitutive equations for finite extensible non-linear elastic dumbbells with the closure proposed by Peterlin (FENE-P model). We present the results of three-dimensional simulations in a range of $\\mbox{Ca}$ which is broad enough to characterize all the three characteristic mechanisms of breakup in the confined T-junction, i.e. ${\\it squeezing}$, ${\\it dripping}$ and ${\\it jetting}$ regimes. The various model parameters of the FENE-P constitutive equations, including the polymer relaxation time $\\tau_P$ and the finite extensibility parameter $L^2$, are changed to provide quantitative details on how the dynamics and break-up properties are affected by viscoelasticity. We will analyze cases with ${\\it Droplet ~Viscoelasticity}$ (DV), where viscoelastic properties are confined in the dispersed (d) phase, as well as cases with ${\\it Matrix ~Viscoelasticity}$ (MV), where viscoelastic properties are confined in the continuous (c) phase. Moderate flow-rate ratios $Q \\approx {\\cal O}(1)$ of the two phases are considered in the present study. Overall, we find that the effects are more pronounced in the case with MV, as the flow driving the break-up process upstream of the emerging thread can be sensibly perturbed by the polymer stresses.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2015-08-01T16:07:01.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "lattice boltzmann study",
      "microfluidic t-junctions",
      "droplet dynamics",
      "viscoelasticity",
      "viscoelastic properties"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 16,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}