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Keywords:

  • pipe flow;
  • mixing;
  • dispersion;
  • displacement;
  • non-Newtonian fluids

Abstract

We present a methodological framework for estimating the degree of mixing between successive miscible fluids pumped along a near-horizontal pipe. Either or both of the fluids can be non-Newtonian, of Herschel–Bulkley type. Overall it is considered that the objective is to minimise mixing. In laminar regimes our estimates are based on front velocity of the leading displacement front. In turbulent regimes the spreading mechanism is dispersion. In addition to the estimates of mixing volumes/lengths, we also predict a minimal flow rate necessary in order to achieve a successful displacement of the residual fluid. © 2013 Canadian Society for Chemical Engineering