Transport coefficients for inelastic Maxwell mixtures

The Boltzmann equation for inelastic Maxwell models is used to determine the Navier-Stokes transport coefficients of a granular binary mixture in $d$ dimensions. The Chapman-Enskog method is applied to solve the Boltzmann equation for states near the (local) homogeneous cooling state. The mass, heat, and momentum fluxes are obtained to first order in the spatial gradients of the hydrodynamic fields, and the corresponding transport coefficients are identified. There are seven relevant transport coefficients: the mutual diffusion, the pressure diffusion, the thermal diffusion, the shear viscosity, the Dufour coefficient, the pressure energy coefficient, and the thermal conductivity. All these coefficients are {\em exactly} obtained in terms of the coefficients of restitution and the ratios of mass, concentration, and particle sizes. The results are compared with known transport coefficients of inelastic hard spheres obtained analytically in the leading Sonine approximation and by means of Monte Carlo simulations. The comparison shows a reasonably good agreement between both interaction models for not too strong dissipation, especially in the case of the transport coefficients associated with the mass flux.Comment: 9 figures, to be published in J. Stat. Phy

Stability of a rivulet flowing in a microchannel

publisher: Elsevier articletitle: Stability of a rivulet flowing in a microchannel journaltitle: International Journal of Multiphase Flow articlelink: http://dx.doi.org/10.1016/j.ijmultiphaseflow.2014.10.012 content_type: article copyright: Copyright © 2014 Elsevier Ltd. All rights reserved.publisher: Elsevier articletitle: Stability of a rivulet flowing in a microchannel journaltitle: International Journal of Multiphase Flow articlelink: http://dx.doi.org/10.1016/j.ijmultiphaseflow.2014.10.012 content_type: article copyright: Copyright © 2014 Elsevier Ltd. All rights reserved.publisher: Elsevier articletitle: Stability of a rivulet flowing in a microchannel journaltitle: International Journal of Multiphase Flow articlelink: http://dx.doi.org/10.1016/j.ijmultiphaseflow.2014.10.012 content_type: article copyright: Copyright © 2014 Elsevier Ltd. All rights reserved.publisher: Elsevier articletitle: Stability of a rivulet flowing in a microchannel journaltitle: International Journal of Multiphase Flow articlelink: http://dx.doi.org/10.1016/j.ijmultiphaseflow.2014.10.012 content_type: article copyright: Copyright © 2014 Elsevier Ltd. All rights reserved

Smooth printing of viscoelastic micro films with a flow focusing ejector

The flow focusing principle has recently been shown to successfully generate micrometer viscoelastic jets. In this technique, the liquid jet is gently extruded by the smooth suction caused by the acceleration in the discharge orifice of a co-flowing gas stream. Nozzle clogging is a rare phenomenon in flow focusing because the emitted jet is much thinner than all the passages and orifices in the device. The Weber number characterizing the jet is very small, which reduces the liquid impact velocity when it is printed onto a substrate. In this article, we report the design, build, and characterization, for the first time, of a flow focusing ejector. Using an aqueous polyacrylamide solution, we examine the dependence of the diameter and velocity of the jet upon the ejector control parameters: injected flow rate, applied pressure drop, and distance from the discharge orifice. Moreover, we also study the deposition onto a glass substrate moving at a constant speed, paying attention to the influence that this parameter has over the printing quality. Finally, we illustrate the capabilities of the ow focusing ejector by printing lines of poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) and polyvinylpyrrolidone, fluids commonly used in flexible electronics and tissue engineering, respectively

Caricature 1798-1799

Nightly visitors at St Ann’s Hil

Design workshops of the world : the production and integration of industrial design expertise into the product development and manufacturing process in Norway and the United Kingdom

To gain competitive advantage an increasing proportion of companies incorporate design into the product development process; it has become a critical determinant of competitive success. Design expertise is either provided internally or externally. Thus, in common with management consultancy, independent firms are increasingly providing design expertise to clients. Over the last ten years the British and Norwegian governments have emphasised the contribution made by industrial design to national competitiveness. This takes two forms: the export of design services, and the added value that comes from the incorporation of design into products and services. This paper explores the role of design services in the production process and undertakes a preliminary analysis of the structure and geography of the design industry in the UK

Stability of liquid bridges between coaxial equidimensional disks to axisymmetric finite perturbations: A review

This paper reviews the dynamics of breaking or oscillating axisymmetric liquid bridges, and estimates of the energy which is needed to break a liquid bridge. We consider a liquid bridge spanning two coaxial equal disks with sharp edges and held by surfacetension forces. The liquid volume is assumed to be conserved under perturbations, and the contact lines are pinned to the disk edges. The perturbations are finite and axisymmetric. An analysis is based on the one-dimensional models previously used in capillary jet theory and last several decades for study a liquid bridge dynamics. According to the scientific project JEREMI (Japanese and European Research Experiment on Marangoni Instabilities), the first stage of the space experiment on ISS will involve an isothermal liquid bridge with a gas blowing parallel to the axial direction of the bridge. The geometry corresponds to a cylindrical volume liquid bridge coaxially placed into an outer cylinder with solid walls. The gas enters the annular duct bounded by the outer cylinder and the internal system consisting of supporting vertical rods and the liquid bridge. Considering that the bridge is small (the rod's radii are 3 mm) and the gas velocity is typically (0.25 / 0.37) m/s, the perturbations cannot be considered small. Thus, one may assume that the amplitude of the liquid bridge perturbations is sufficiently large that departures from linearity must be considered. © Springer Science+Business Media B.V. 2012.SCOPUS: re.jinfo:eu-repo/semantics/publishe