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We investigated the magnetorheological (MR) properties of the carbon nanotube (CNT)-Co0.4Fe0.4Ni0.2 composite suspension to find a high-performance MR fluid with excellent stability. The composites were fabricated by chemical reduction of Co0.4Fe0.4Ni0.2 on the surface of amine-functionalized CNTs. A synergistic effect between the high aspect ratio of the CNTs and the strong magnetic polarization of the Co0.4Fe0.4Ni0.2 led to stronger MR performance of the nanocomposite particle suspension. The MR fluid exhibits an unexpected high yield stress value that is 13 times greater than that of a CNT-Fe3O4 suspension at a magnetic field strength of 343 kA/m. Nonmagnetic CNTs form a three-dimensional networklike structure, imparting surprisingly large additional yield stress to the CNT-Co0.4Fe0.4Ni0.2 nanocomposite MR suspension. The low density of the CNTs resulted in much better long-term stability for the CNT-Co0.4Fe0.4Ni0.2 nanocomposite suspension than the MR fluid containing only Co0.4Fe0.4Ni0.2.

We have verified that the method of multi-particle collision dynamics (MPCD) is able to activate a physically reasonable level of random motion in the medium of virtual fluid particles and activate...

Viscous fingering is observed experimentally when a bidisperse suspension displaces air inside a Hele-Shaw cell, despite the stabilising viscosity ratio between the invading (suspension) and defending (air) phases. Careful experiments are carried out to characterise this instability by either systematically varying the large-particle concentrations $\unicode[STIX]{x1D719}_{l0}$ at constant total concentrations $\unicode[STIX]{x1D719}_{0}$, or changing $\unicode[STIX]{x1D719}_{0}$ with fixed $\unicode[STIX]{x1D719}_{l0}$. Leading to the instability, we observe that larger particles consistently enrich the fluid–fluid interface at a faster rate than small particles. This size-dependent enrichment of the interface leads to an earlier onset of the fingering instability for bidisperse suspensions, compared to their monodisperse counterpart of all small particles. In particular, even the small presence of large particles is shown to effectively lower the total particle concentration needed for fingering, compared to the all-small-particle case. We hypothesise that the key mechanism behind this enhanced viscous fingering is the size-dependent nature of shear-induced migration of particles far upstream from the interface. A reduced equilibrium model is derived based on the modified suspension balance model to verify this hypothesis, in reasonable agreement with experiments.

We present results of interface-resolved simulations of heat transfer in suspensions of finite-size neutrally-buoyant spherical particles for solid volume fractions up to 35% and bulk Reynolds numbers from 500 to 5600. An Immersed Boundary–Volume of Fluid method is used to solve the energy equation in the fluid and solid phase. We relate the heat transfer to the regimes of particle motion previously identified, i.e. a viscous regime at low volume fractions and low Reynolds number, particle-laden turbulence at high Reynolds and moderate volume fraction and particulate regime at high volume fractions. We show that in the viscous dominated regime, the heat transfer is mainly due to thermal diffusion with enhancement due to the particle-induced fluctuations. In the turbulent-like regime, we observe the largest enhancement of the global heat transfer, dominated by the turbulent heat flux. In the particulate shear-thickening regime, however, the heat transfer enhancement decreases as mixing is quenched by the particle migration towards the channel core. As a result, a compact loosely-packed core region forms and the contribution of thermal diffusion to the total heat transfer becomes significant once again. The global heat transfer becomes, in these flows at volume fractions larger than 25%, lower than in single phase turbulence.

The magnetization induced by oscillatory magnetic-field in a polydispersive superparamagnetic-suspension shows a nonlinearity which strongly depends on the applied frequency. Referring to the initially-measured complex magnetic-susceptibility in function of field-strength, the highly-nonlinear curve of dynamic magnetization at low frequency tends to be linear at higher frequency. Likewise, the dynamic susceptibility appears to be less field-strength dependent at higher frequency, emphasizing a frequency-dependence of magnetically-induced particle-dynamics. This finding is attributable to the imaginary part of magnetization which saturates at lower field-strength of low-frequency magnetic-field. Hence, Brownian relaxation losses should be constant after the saturation due to a confinement of particle rotations.

We have proposed a new repulsive layer model for describing the interaction between steric layers of coated cubic particles. This approach is an effective technique applicable to particle-based sim...

The gelation of FeOOH rod particles in a glycerin-water mixture under shear flows is investigated using rheological measurements. The average length and the average diameter of the rod particles are 1 μm and 120 nm, respectively. The van der Waals energy is much larger than the Brownian and electrostatic contributions. To examine the effect of shear history on gelation, two different kinds of experimental procedures are used: A strong, but short preshear followed by a creep test and a preshear for a long time followed by a creep test. The rod particle suspension becomes a gel during the creep test showing the plateau in G′ and yield stress. The gelation time during the creep test is dependent on preshear time while it is not affected by the preshear stress for a short time before the creep test. Both the plateau in G′ and the yield stress are larger when the preshear time is longer. The gelation appears to occur by two steps of the formation of flocs by the aggregation of individual particles and then the formation of the sample spanning network by the aggregation of the flocs. Gel strength appears to be dependent on floc size which is determined by the imposed shear stress in the present case of shear induced gelation.

The effects of temperature and low-volume concentration on the dynamic viscosity of the Al2O3/water and Al2O3/ethylene glycol/water nanofluids are investigated. Nanofluids were prepared and characterised. Data were collected for temperatures ranging from 25 to 80°C. The presence of aggregated Al2O3 nanoparticles in the fluid, with average diameter of 109 nm which is ∼8 times the primary diameter (13 nm) of Al2O3 nanoparticles was witnessed. Furthermore, only at temperature below 40°C water-based alumina nanofluid at 0·05% v/v showed Newtonian behaviour. On the other hand, Al2O3/ethylene glycol/water mixture exhibited Newtonian behaviour. Results clearly showed the presence of a critical temperature, beyond which the particle suspension properties were noticed to be radically changed, which results in activating the hysteresis phenomenon. The hysteresis phenomenon on viscosity measurement, which is believed to be the first observed for ethylene glycol/water-based nanofluids, has raised serious concerns reg...

Nearly all tubes and pores used to transport solids in fluids, such as arteries and filters, are subject to clogging. The length scales and geometries of these tubes are well defined. In spite of this knowledge, the collective clogging behavior of multiple tubes has not yet been connected to their shapes and sizes. We investigate the clogging behavior of ten parallel tubes, which we model with ten parallel tapered microchannels using poly(styrene) beads to induce clogging events. The clogging behavior depends on the channel geometry as well as the shear stress particles are subjected to. Although our microchannels model filters, our results can be applied to the clogging behavior of a broad range of applications such as the clogging in arteries, inkjets, or xylem in trees.

Polydopamine (PDA)-Au Janus particles were obtained by simply adding HAuCl4 to a PDA particle suspension, prepared via self-polymerization of dopamine in basic solution at room temperature. The structures of the PDA-Au particles are readily controlled by electrostatic repulsion between the constituent particles, which can be realized simply via adjusting the environmental pH. PDA-Au Janus particles are formed only in a narrow pH range of 2.5-3.0 due to the properly enhanced electrostatic repulsion between the Au particles growing on as-prepared PDA particles and between the Au and PDA particles. The obtained PDA-Au Janus particles can become interfacially active and self-assemble at oil/water interfaces as a result of spatially well-separated hydrophilic (PDA) and hydrophobic (Au) domains on the surfaces, reminiscent of amphiphilic molecules. Refereed/Peer-reviewed

This review describes the development and application of the multipass rheometer; a servo hydraulically driven two piston device that enables rheology and precise processing measurements to be carried out within an enclosed volume. The apparatus development and then specific application areas are highlighted. In particular, application to rheology, polymer processing and foaming are considered.

The purpose of this paper is to study the onset of bioconvection in a horizontal layer filled with a nanofluid that also contains gyrotactic microorganisms. The idea is to use microorganisms to induce or enhance convection in a nanofluid. A linear instability analysis is used to solve this problem. A Galerkin method is utilized to obtain an analytical solution for the critical Rayleigh number for the non-oscillatory situation. As in the case of a regular nanofluid (without the microorganisms), the presence of nanoparticles can either reduce or increase the value of the critical Rayleigh number, depending on whether the basic nanoparticle distribution is top-heavy or bottom-heavy. In contrast, the effect of gyrotactic microorganisms is always destabilizing.

To date, prediction of particulate erosion in suspension ows has been unreliable, with the state-of-the-art reporting errors upwards of 40% [Zhang et al., Wear 240 (2000) 40–51]. These errors stem chiefly from the underlying erosion models, significantly hindering understanding of erosion dynamics in suspension ows and design of plant equipment with improved erosion characteristics. Herein we present improved experimental methodologies and data analysis techniques based on computational fluid dynamics (CFD) to solve the associated inverse problem and generate high precision models of suspension erosion. These methods are applied to a test case of silica sand particles eroding an aluminium surface, and the resultant data is fitted to an erosion function. To test the predictive accuracy of the fitted model, CFD predictions are compared with an independent erosion experiment, and the peak erosion rate is found to agree to within 1%. These results suggest that the methodologies presented provide a sound basis for high precision suspension erosion modeling.

We develop a novel patterning technique to create 3D patterns of micro and nanoparticle assembly via evaporative self-assembly based on the coffee-ring effect of an evaporating suspension. The principle of the technique is analyzed theoretically by the scaling analysis of main parameters of the process and the scaling effect, the effect of the volume, the concentration of the suspension, and the effect of surface treatment on the patterning are studied. On the basis of the presented technique, we demonstrate that the patterns of 3D assembly of various sizes of microparticles (Silica), metal oxide nanoparticles (TiO(2), ZnO), and metallic nanoparticles (Ag) can be successfully generated by low-concentrated particle suspension (1.25-5 wt %) without additional sintering steps, and we also show the geometries of the patterns can be finely controlled by adjusting the parameters of the process.

The optimal conditions of preparation of aqueous suspensions of individual single-wall carbon nanotubes with Pluronic F127 surfactant have been determined. The variable parameters are the surfactant concentration, the regimes of ultrasonication and ultracentrifuging. The stable suspensions of bio-molecules (such as albumin) and nanotubes dispersed with Pluronic have been demonstrated.

The problem of the stability of the sandy bottom of a rectangular channel with respect to spatially onedimensional perturbations is formulated. The channel stability problem is solved using the sediment discharge formula modified by taking into account the effect of free-surface perturbations on sediment transport. Analytic dependences of the propagation velocity of bottom perturbations on time are obtained for small Froude numbers. Wavelengths for the most rapidly growing bottom perturbations are obtained analytically, and the problem of the evolution of a single bottom perturbation is solved.

Turbulent dispersed multiphase flows are common in many engineering and environmental applications. The stochastic nature of both the carrier-phase turbulence and the dispersed-phase distribution makes the problem of turbulent dispersed multiphase flow far more complex than its single-phase counterpart. In this article we first review the current state-of-the-art experimental and computational techniques for turbulent dispersed multiphase flows, their strengths and limitations, and opportunities for the future. The review then focuses on three important aspects of turbulent dispersed multiphase flows: the preferential concentration of particles, droplets, and bubbles; the effect of turbulence on the coupling between the dispersed and carrier phases; and modulation of carrier-phase turbulence due to the presence of particles and bubbles.

The effect of the temperature on the dynamic behavior of PMMA−PHSA hard spheres under the influence of external electric field is described. By using a very uncommon light scattering setup for low ...

The complex rheological behaviour of suspensions is very strongly affected by the details of the microstructure and the interparticle forces by which it is controlled. The difficulties involved in characterizing the microstructure, in particular during flow, caused the development of suspension rheology to lag behind that of polymer rheology. Progress in theory, experiments and simulation is rapidly changing the picture, providing opportunities for further significant developments. Possible evolutions in six areas of suspension rheology are discussed here.

The wear behavior of polytetrafluoroethylene (PTFE) and polyimide (PI) has been comparatively evaluated under dry sliding and simulated sand-dust conditions. An improved block-on-ring wear tester equipped with an attachment for simulating the sand-dust environment was used to evaluate the abrasive wear behavior of materials. The sand collected from the Yellow River of China was used to simulate the sand-dust environment, also different loads and sand-dust sizes were chosen for tribological tests. The two chosen polymers showed different wear behavior under sand-dust conditions and the wear rates of PTFE were much lower under sand-dust conditions than under dry sliding conditions. This was attributed to the formation of the tribolayer on the worn surfaces during the abrasive wear process. The sand-dust enhanced the wear resistance of PTFE, but reduced that of PI because, in contrast to PTFE, there was no tribolayer formed on the PI worn surface. The wear rate of PTFE increased under sand-dust conditions while the wear rate of PI decreased with the increase of applied load. The higher hardness of PI and fragmentation of abrasive particles under high loads accounted for the decrease in wear rate as load increased.

There are two conventional boundary treatment methods in molecular dynamics (MD) simulation for particle suspension or fiber in cross flow. One is that the fiber is represented by evenly spaced atoms, the other is that the fiber is treated as one mass point. The calculations with the two boundary treatment methods have been compared, it is found that, with the same properties, both methods could generate slip boundary condition on the fiber surface, however the one mass point method could result in very large slip boundary condition on the fiber surface, and the discrepancy could be as high as 2600%.

Spherical and irregular microparticles both in the size of 5 μm were put into the de-ionized water respectively to form different suspensions, and vibrating cavitation experiments were performed in the two kinds of suspensions. After the experiment, the damages on the specimen surfaces were measured and free radicals in suspensions were detected. It was found that suspensions with particles cause more severe cavitation erosion than those without particles. Compared with a spherical particle, the shape of the irregular particle has little effect on the number of the cavities, but it causes abrasion on the solid surface besides the cavitation erosion.

Journal of Fluid Mechanics, 612, ISSN:0022-1120, ISSN:1469-7645

In this Article, we report the application of the quartz crystal microbalance (QCM) to study the evaporation of colloidal suspension droplets. Droplets of alumina particle suspensions with varying particle size and solid concentration have been investigated. Characteristic responses of the resonance frequency of the QCM associated with the different evaporation stages have been established. Quantitative analysis of the experimental results has been performed by the proposed QCM models. An interesting finding is that frequency increase after complete drying has been observed in some cases. Interpretation of the frequency increase has been developed in terms of the contact stiffness. The possible physical mechanisms are also discussed and quantified in terms of various interparticle forces.

Solutions to the Stokes problem for particles suspended in a moving fluid express mathematically their active (nonaffine) advection. A mesoscopic model of the microhydrodynamic formulation of the advection is developed and its rheological consequences are investigated. The model is constructed as a particular realization of a framework (GENERIC) guaranteeing the compatibility of dynamics with thermodynamics.

The Duhamel theorem is a useful classical result that allows finding the solution to a single phase thermal diffusion problem subject to time dependent heat sources and time dependent boundary conditions in terms of known solutions to the equivalent problem when the heat sources and boundary conditions are independent of time. The present paper presents the proof to the Duhamel theorem for dual phase thermal diffusion applications.

The unusual properties of single-walled carbon nanotubes (SWCNTs) make them attractive for applications in the realm of molecular electronics, but also cause severe experimental difficulties in the purification and handling of these materials. One important step toward routine use of SWCNTs is the development of concentrated, monodisperse suspensions that are suitable for conventional manipulation and chromatography. We have studied the effect of the structure of oligodeoxynucleotides on their ability to generate such suspensions of SWCNTs, as well as the ability to release the nanotubes site-selectively after (local) heating. Interestingly, short DNA strands were found to be better "surfactants" for the solubilization process than longer ones. The kinetic stability data suggest that the affinity of oligodeoxynucleotides for SWCNTs is greater than that for complementary DNA strands. The implications of this finding for DNA-based nanostructuring are discussed.

In the last decade, a number of investigations have been conducted to identify the possible mechanisms that contribute to the enhanced effective thermal conductivity of nanoparticle suspensions (nanofluids). The Brownian motion of the nanoparticles in these suspensions is one of the potential contributors to this enhancement and the mechanisms that might contribute to this are the subject of considerable discussion and debate. In the current investigation, the mixing effect of the base fluid in the immediate vicinity of the nanoparticles caused by the Brownian motion was analyzed, modeled and compared with existing experimental data available in the literature. The simulation results indicate that this mixing effect can have a significant influence on the effective thermal conductivity of nanofluids.

Measurements of the frequency- and field-dependent complex susceptibility, χ(ω, H), of a suspension of cobalt particles are presented. The measured data indicate the presence of aggregates in the sample and raise the issue of how these polarized aggregates, subjected to a cyclic polarizing field, influence the isotropic properties of the fluid. Here we present the results of such an investigation which is centred on the application of the Weierstrass hypothesis, which dictates that, for the magnetic fluid to be isotropic, a plot of the graph of χ(ω, H) versus H should be symmetrical about the vertical axis. We demonstrate this to be so and also show that if χ is complex, with χ(ω, H) = χ'(ω, H) − iχ''(ω, H) then plots of χ'(ω, H) and χ''(ω, H) versus H are also symmetrical in the isotropic case.

Slender-body asymptotic theory is applied to determine the electro-magneto-phoretic motion of a freely suspended elongated particle which is arbitrarily oriented relative to uniformly applied electric and magnetic fields.

Adsorption isotherms for water vapor on powdered cesium iodide are reported. Both macroscopic and microscopic (single-particle) samples of CsI powder from the same source were studied by two differ...

An approach to constructing the quantitative nonuniformity characteristics of liquid vibrations is proposed. A new problem of the motion of an inclusion in a vibrating liquid is considered.

Significant microstructural anisotropy is known to develop during shearing flow of attractive particle suspensions. These suspensions, and their capacity to form conductive networks, play a key role in flow-battery technology, among other applications. Herein, we present and test an analytical model for the tensorial conductivity of attractive particle suspensions. The model utilizes the mean fabric of the network to characterize the structure, and the relationship to the conductivity is inspired by a lattice argument. We test the accuracy of our model against a large number of computer-generated suspension networks, based on multiple in-house generation protocols, giving rise to particle networks that emulate the physical system. The model is shown to adequately capture the tensorial conductivity, both in terms of its invariants and its mean directionality.

Cavitation and silt erosion often co-exist causing severe damage. The effect that the silt erosion is worsened by the presence of cavitation is here referred as cavitation enhancement of silt erosion. Its mechanism is still not fully understood despite the effort made in past decades. In this article, the need for a micro model is firstly demonstrated by reviewing the phenomenon from the viewpoint of fluid-particle interaction. Then, the postulated model is presented from the viewpoint of a driving force. The potential of this model in furthering our understanding is also demonstrated by re-visiting Sato's experimental study on synergetic erosion. Further development of this model through experimental and numerical simulations is thus recommended. (c) 2005 Elsevier B.V. All rights reserved.

This paper introduces a model for short-range fibre-fibre interaction and combines it with the Shaqfeh-Fredrickson result for long-range hydrodynamic interactions. The short-range interactions are ...

Considering the carbon nanotubes’ (CNTs) orientation distribution a new model of effective thermal conductivity of CNTs-based composites is presented. Based on Maxwell theory, the formulae of calculating effective thermal conductivity of CNTs-based composites are given. The theoretical results on the effective thermal conductivity of CNTs/oil and CNTs/decene suspensions are in good agreement with the experimental data. The model is valid for the transport properties of the CNTs-based composites.

The heat conduction mechanism in nanofluid suspensions is derived for transient processes attempting to explain experimental results, which reveal an impressive heat transfer enhancement. In particular, the effect of the surface-area-to-volume ratio (specific area) of the suspended nanoparticles on the heat transfer mechanism is explicitly accounted for, and reveals its contribution to the specific solution and results. The present analysis might provide an explanation that settles an apparent conflict between the recent experimental results in nanofluid suspensions and classical theories for estimating the effective thermal conductivity of suspensions that go back more than one century (Maxwell, J.C., 1891, Treatise on Electricity and Magnetism). Nevertheless, other possible explanations have to be accounted for and investigated in more detail prior to reaching a final conclusion on the former explanation.

The present knowledge regarding the reasons why solutions of conductive polymers (ICP) can not be made, and the most recent status of insight into feasibility and properties of dispersions is being reviewed. Dispersions are now available with conductivity values exceeding 200 S/cm. New applications in the supercapacitor field and in printed circuit board manufacturing are becoming accessible.

Characteristics of organic–mineral complexes have been theoretically and experimentally studied in the paper, based on the method of integral light scattering indicatrix. Modelling of optical properties was realized using models of the coated spherical particles with a shell which is constant and changeable in the refractive index profile. General regularities have been revealed and generalized parameters for the method of integral light scattering indicatrix have been suggested.

The motion of a torque-free slender axisymmetric fibre in simple shear flow is examined theoretically for small but finite coefficient related to the Jeffery period of the rotating fibre.

Periodic arrays of particles, foams, and other structures impregnated with a static fluid play an important role in heat transfer enhancement. In this article, we develop a numerical method for com...

A micro-contact model for chemical–mechanical polishing (CMP) of silicon wafer is presented. The model is developed on the basis of the Greenwood-Williamson micro-contact mechanics. The atomic force microscope (AFM) is used as a polishing test apparatus to evaluate the removal rate by a single particle in a CMP slurry. Using this model and AFM, the simulation on polishing of SiO2 is performed. The model is evaluated by comparing the simulated polishing rate and that experimentally determined by real CMP processes. The simulation result and experiment result are in good agreement. It suggests that the combination of the model and AFM polishing test can be used to estimate the removal rate of SiO2 CMP and may be used to study the effects of different materials, slurry and operating condition on CMP process.

Zero-shear viscosities of dense colloidal suspensions are strongly correlated with the dynamics of particles in cages produced by nearest neighbors. At a given volume fraction, repulsive or attractive interparticle forces are expected to enhance cages, slow dynamics, and increase zero-shear rate viscosities. However, recent studies have shown that hard sphere glasses melt when depletion attractions are introduced, and this is correlated with the break up of local cages and enhancement of density fluctuation relaxation rates. Glass formation in hard sphere suspensions is attributed to the loss of free volume and the entropic localization of particles. Melting is associated with the ability of depletion attractions to increase the local free volume due to a decrease in nearest-neighbor cages. Here, we report evidence for the reduction in the zero-shear viscosity of dense hard and near-hard sphere suspensions, as the strength of depletion attractions increases, at volume fractions well below the experimental...

This paper describes a simulation method for the equivalent magnetic permeability of mangetorheological (MR) fluids considering cluster formation of suspended particles. The cluster formation under a magnetic field is simulated by cellular automata (CA). Simulated cluster structures are qualitatively equivalent to those observed experimentally. Considering this structure, magnetic permeability analysis is conducted on a representative MR fluid by the finite element method. The equivalent permeability in the MR fluid was obtained from the average magnetic flux density and field. The time evolution of the magnetic characteristics of the MR fluid is shown to correspond to the time evolution of cluster formation.

It is argued that a particularly simple kind of many-body interaction can be developed by making the one-body or self-energy terms in the potential depend on a local environmental factor, such as the local density, in some way. Two examples of this are considered: a toy model for macroion suspensions, and an extension to the dissipative particle dynamics simulation method.

The objective of this work was to analyze the performance of three continuous thickeners of different geometries in steady-state operation: the conical-convergent, with a cross section area decreasing with the depth, the conical-divergent, in which the cross section area increases with the depth and the cylindrical. The experimental runs were made in prototypes, operating with aqueous suspensions of barium sulfate with a density of 4520 kg/m 3 . In order to verify how the thickeners capacity behaves as a function of the geometry. Computer simulations (Maple® software) based on the model proposed by in a previous article were compared to the experimental data. It was verified through both, the computer simulations and the experimental tests, that the cylindrical thickeners presented smaller capacities than the conical-divergent thickeners; however larger than the one presented by the conical-convergent thickener. It was also observed that the larger the absolute value of the conical vertex's angle, the bigger is the difference among the capacities of the conical and cylindrical systems. The model used describes well the experimental behavior of continuous thickeners in steady-state operation.

Hydrocyclones constitute an important class of devices intended for the solid-liquid suspensions separation. Those equipments are divided in several families, which differ to each other in the geometric relationships. The filtering hydrocyclone is a device which consists of a cyclone, whose conical section was replaced by a conical filtering wall. The objective of this work is to compare the performance of the filtering hydrocyclones of the Bradley's and Rietema's designs. The experimental apparatus was composed of a well-stirred tank, a centrifugal pump, an agitator, valves and the filtering hydrocyclones with Bradley's and Rietema's geometries. The experimental results obtained with the filtering hydrocyclones in the same operation conditions that their conventional devices, allow to conclude that the performance of the hydrocyclones of the families Bradley and Rietema is significantly influenced by the presence of the filtering medium. The Rietema's filtering hydrocyclones supplied smaller volumetric feed flowrate in relation to the conventional device, the Bradley's filtering hydrocyclones presented increments for this same variable. In both geometry, the overall efficiencies were influenced by the underflow-to-throughput ratio.

A comparison was made of the behaviour of a magnetorheological suspension under steady shear flow and constant velocity squeezing flow. The strain rates and sample dimensions were chosen to be comparable in the two deformation modes, and the dependence of the mechanical properties on the magnetic flux density B was investigated. The measurements found that the mechanical response under squeezing flow scaled as B0.91, whereas the response under shearing scaled as B1.4, close to theoretical predictions. This difference of the field dependence between the shearing and squeezing flows was possibly due to the different microstructural rearrangement processes which occur in the two deformation modes.