Rheological Characterization of Fluids Using NMR Velocity Spectrum Measurements

Abstract

This paper demonstrates the use of the nuclear magnetic resonance (NMR) velocity spectrum to rheologically characterize a fluid‐like material in steady tube flow. The velocity spectra for four different materials, an oil‐water solution, a polyacrylamide solution, tomato juice and a paper pulp suspension are measured and qualitative agreement with theory based upon simple constitutive models is demonstrated. These materials exhibit Newtonian, power law and Bingham plastic behavior. Homogeneous and heterogeneous samples are used and the applicability to each discussed. The velocity spectra from NMR experiments allows for a nonin‐vasive method of monitoring flow behavior and as such has applications to online process monitoring of rheological properties.

Local Velocity and Concentration of the Single Components in Water/Oil Mixtures Monitored by Means of MRI Flow Experiments in Steady Tube Flow

“…Trumbetas et al [26], for example, used NMR to determine the oil content of fatty emulsions. Seymour et al [27] characterized fluids (tomato juice, oil-water solution) using NMR velocity spectrum measurements. The complex materials were modeled rheologically as simple non-Newtonian fluids.…”

Determination of the Power Law Exponent from Magnetic Resonance Imaging (MRI) Flow Data

“…At thermodynamic equilibrium, the contact angle is dependent on the surface tensions c involved in the drop shape, which is described by the fundamental Young equation (Fig. 1a, Eq.(1)) [2,3]. The product of the surface tension of the liquid c lg and of the cosine of the contact angle cos h is termed wetting tension c B .…”

“…First experiments on non-Newtonian fluids were performed by Powell et al [6], Seymour et al [3], Gibbs et al [7] as well as by Manz et al [2]. Mueller et al [4] investigated the flow of non-Newtonian fluids (Xanthan gum solutions) through bead packing with a visual technique.…”

“…The velocity probability distribution function can thereby be determined [3]. This description is useful to differentiate the flow behavior of Newtonian and non-Newtonian fluids.…”

“…The experiments allow the rapid determination of rheological properties of complex fluids. Seymour et al [3] investigated the flow of non-Newtonian materials, polyacrylamide and tomato juice, in single tubes. Their measurements were in qualitative agreement with the theory.…”