Flow Problems with a Free Surface

We investigate a number of flow problems involving fluids with a free surface such as evaporation-driven flows as well as spreading and phase transition of droplets and impinging jets. The impact and spreading of liquid droplets on a smooth solid substrate has a wide range of applications in nature and industry. Examples include ink-jet printing, rain drop dynamics, fuel combustion, spray cooling, coating, and many others. We study the dynamics of impact and spreading of Newtonian and non-Newtonian droplets on solid surfaces with different wetting properties.
Evaporation of a polymer solution is widely used in many industrial processes such as solvent-casting, microneedle fabrication, ink-jet printing, adhesive bonding and also painting and coating purposes. The microfluidics involved during this evaporation process can affect the shape and properties of the final dry film. Different flow phenomena including evaporation-driven convective transport and Marangoni flow are involved in thin-film evaporation of polymer solutions. Optical measurement techniques such as micro particle image velocimetry (PIV) and micro laser induced fluorescence (LIF) are being used to measure the evaporation induced velocity field and polymer concentration field over time.

  • X. Liu, N.J. Balmforth, B. Stoeber, S.I. Green, “Impingement of a circular liquid jet on a moving wall”, Physical Review Fluids, vol. 8, no. 9, art. 094101, 2023.
  • A. Rostami, B. Stoeber, S.I. Green, “Experimental Investigation of Substrate Roughness Effects on High-Acceleration Film Splitting”, Experiments in Fluids, vol. 63, no. 11, art. 176, 2022.
  • X. Liu, S.I. Green, B. Stoeber, N.J. Balmforth, “Flow of a Shallow Film over a Moving Surface”, Physics of Fluids, vol. 34, no. 8, art. 083602, 2022.
  • H. Rahmani, B. Stoeber, N. Balmforth, S.I. Green, “Lubricated rolling over a pool”, Journal of Fluid Mechanics, vol. 934, art. A5, 2022.
  • M. Jalaal, B. Stoeber, N.J. Balmforth, “Spreading of viscoplastic droplets,” Journal of Fluid Mechanics, vol. 914, A21, 2021.
  • M. Jalaal, C. Seyfert, B. Stoeber, N.J.C. Balmforth, “Gel-Controlled Droplet Spreading,” Journal of Fluid Mechanics, vol. 837, pp. 115-128. 2018.
  • V. Bazargan, B. Stoeber, “Effect of substrate conductivity on the evaporation of small sessile droplets,” Physical Review E, vol. 94, no. 3, art. no. 033103, 2016.
  • M. Jalaal, N. Balmforth, and B. Stoeber,” Slip of Spreading Viscoplastic Droplets,” Langmuir, vol. 31, no. 44, pp. 12071-5, 2015.