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Title: Numerical simulations of mounding and submerging flows of shear-thinning jets impinging in a container

Continuous jets of non-Newtonian fluids impinging on a fluid surface exhibit instabilities from jet buckling and coiling at low Reynolds numbers to delayed die swell, mounding, and air entrainment at higher Reynolds numbers. Filling containers with complex fluids is an important process for many industries, where the need for high throughput requires operating at high Reynolds numbers. In this regime, air entrainment can produce a visually unappealing product, causing a major quality control issue. Just prior to the onset of air entrainment, however, there exists an ideal filling regime which we term “planar filling,” as it is characterized by a relatively flat free surface that maintains its shape over time. In this paper, we create a steady-state, 2-D axisymmetric finite element model to study the transition from planar filling to the onset of air entrainment in a container filling process with generalized-Newtonian fluids. We use this model to explore the operating window for Newtonian and shear-thinning (or, more generally, deformation-rate-thinning) fluids, demonstrating that the flow behavior is characterized by a balance between inertial, viscous, and gravitational forces, as characterized by the Reynolds and Froude numbers. A scaling analysis suggests that the relevant parameters for calculating these dimensionless numbers are locatedmore » where the jet impacts the liquid surface, and simulations show that the transition from planar filling to air entrainment often occurs when Re ~ O(10). Our study found that the bottom and side surfaces of the container drastically influence this transition to entrainment, stabilizing the flow.« less
Authors:
 [1] ;  [1]
  1. Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Thermal and Fluid Processes Dept.
Publication Date:
Report Number(s):
SAND2010-7133J
Journal ID: ISSN 0377-0257; 491449
Grant/Contract Number:
AC04-94AL85000
Type:
Accepted Manuscript
Journal Name:
Journal of Non-Newtonian Fluid Mechanics
Additional Journal Information:
Journal Volume: 166; Journal Issue: 19-20; Journal ID: ISSN 0377-0257
Research Org:
Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
Sponsoring Org:
USDOE National Nuclear Security Administration (NNSA); Procter and Gamble Co., Cincinnati, OH (United States)
Country of Publication:
United States
Language:
English
Subject:
42 ENGINEERING; 70 PLASMA PHYSICS AND FUSION TECHNOLOGY; CFD; finite element method; free surface flow; jet; non-Newtonian; shear-thinning
OSTI Identifier:
1426924