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A method is described that allows the ultrasonic absorption coefficient U of liquids to be precisely measured between about 1 and 100 MHz. The automatic measuring procedure can be performed easily and comparatively fast. At high a values t h e accuracy of the method is clearly superior to the more time-consuming resonator technique, which is applied in this frequency range. This accuracy is achieved by careful construction and adjustment of the specimen cell, by semiempirical consideration of diffraction effects within the sample, and by precise calibration of the set-up by a specially designed below cut-off piston attenuator. The short measuring time is enabled by the particular mode of operation also described in this paper.

Between 0.1 and 2000 MHz the ultrasonic absorption spectra and sound velocities of the mixtures of water with some poly(ethylene glycol) monoalkyl ethers have been measured as a function of mole fraction in the complete composition range. The organic constituents are C2E1, i-C3E1, and C4E2. The results are discussed together with previous results for C4E1/water mixtures. The absorption spectra show attributes of relaxation time distribution which can be accounted for by the assumption of the Romanov−Solov'ev model of precritical concentration fluctuations. Debye-type relaxation terms which additionally exist in some spectra are tentatively related to mechanisms of C i E j dimerization by hydrogen bonding and also by hydrophobic interaction. The classical part of the absorption coefficient is evaluated to determine the volume-to-shear viscosity ratio and the sound velocity to obtain the adiabatic compressibility of the liquids. These quantities are also discussed in terms of hydrogen bond network characteristics of the mixtures of different composition.

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Please cite this article as: Lindner, J., Menzel, K., & Nirschl, H., Simulation of magnetic suspensions for HGMS using CFD, FEM and DEM modeling, Computers and Chemical Engineering (2013), http://dx.doi.org/10. 1016/j.compchemeng.2013.03.012 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. Page 1 of 38A c c e p t e d M a n u s c r i p t Properties of magnetic suspensions depend on the fluid, the particles and the magnetic background field. 8The simulation is aimed at understanding the influence of magnetic properties in High Gradient Magnetic 9 Separation processes. In HGMS magnetic particles are collected on magnetic wires for separation. External 10 magnetic forces are calculated or simulated using the Finite Element Method and embedded first in a 11Computational Fluid Dynamics simulation. In the simulation, elliptic and rectangular wires aligned in field 12 direction reach higher separation efficiencies than cylindrical wires. Magnetic forces from FEM with 13 implemented dipole forces in a Discrete Element Method code show magnetically induced agglomeration 14 and yield an acceptable agreement with experiments. Particle deposition on wires is investigated under the 15 influence of different parameters. The porosity of the deposit is dependent on the magnetization of the 16 wire and particles. A centrifugal force of 60 g has an important influence.