Mixing behavior in a confined jet with disparate viscosity and implications for complex reactions

Gokul Pathikonda, Mustafa Usta, Michael C. Ahmad, Irfan Khan, Paul Gillis, Shrikant Dhodapkar, Pradeep Jain, Devesh Ranjan, Cyrus K. Aidun

Research output: Contribution to journalArticlepeer-review

11 Scopus citations


Turbulent shear-driven mixing in a coaxial and co-flowing configuration is studied using experiments and computations to understand and model the effect of viscosity gradients in the flow field. Two liquids with a large disparity in dynamic viscosity are mixed, with a low viscosity, high momentum jet directed into a high viscosity, low momentum co-flow in a pipe. Simultaneous experimental measurements of the velocity and concentration fields are made using high-resolution PIV and PLIF to obtain their turbulent cross-correlation statistics for viscosity ratios of 1 and 40. LES simulations are also performed using dynamic mixing sub-grid model to investigate the three dimensional mixing structure of the flow for the two cases. The overall structure of turbulent mixing in the coaxial confined jet configuration is studied to identify the mixing regions of the flow and the effect of viscosity gradients on the dynamics of the same. Besides the effect of Reynolds number between the two cases that manifests as reduced mixing, it was noted that the transport of turbulent kinetic energy and scalar concentration variance shows significant asymmetries that arise from the viscosity gradients in the field. The scalar mixing structure between the two cases is studied in detail with relevance to complex mixing-limited reactions frequently encountered in such environments. It was found that turbulence production and associated scalar mixing is highly skewed in variable viscosity flows, where the low viscosity regions show enhanced turbulence activity. The implications of such turbulence skewness on the chemistry of reaction systems involving variable viscosity environments are discussed in further detail.

Original languageEnglish (US)
Article number126300
JournalChemical Engineering Journal
StatePublished - Jan 1 2021
Externally publishedYes


  • Disparate viscosity
  • Mixing-limited reactions
  • Turbulent mixing

ASJC Scopus subject areas

  • General Chemistry
  • Environmental Chemistry
  • General Chemical Engineering
  • Industrial and Manufacturing Engineering


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