Effect Of Particle Volume Fraction Research Articles

Pore tortuosity and permeability of particulate composites with random packing superovoidal particles

The permeability of particle packing system depends on the pore porosity and tortuosity, and the microstructure of porous network is related to particle shape and volume fraction. This work employs superovoids to construct the particles formed by weathering or water movement, and proposes a powerful theoretical method to estimate the effects of particle volume fraction, shape and size-polydispersity on pore tortuosity. The permeability of the particulate composite is numerically acquired by lattice Boltzmann method (LBM). Both of the theoretically and numerically obtained data are validated by comparing with the extensive results, which indicates that employed theoretical method and numerical model can be viewed as general strategies suitable for characterizing pore tortuosity and permeability of particulate composite. The findings establish the quantitative relationship of “component-microstructure-property” for particle packing system, which can provide some guidance for optimizing particulate composites.

Ionic strength effect on the structure and dynamics of colloidal dispersions with weak attractive interactions

We present a macro- and microrheological study of the effect of ionic strength on the phase behavior, structure and flow properties of colloidal dispersions stabilized by short-range repulsive interactions inferred via co-polymerization of weak acid groups. We investigated the impact of ionic strength, by varying the concentration of natrium chloride (NaCl), on dispersions with only repulsive interactions, but also when additional attractive depletion forces are present due to added non-absorbent polymer, namely polyethyleneoxide (PEO). For dispersions with only repulsive electrosteric interactions, at low particle volume fractions (ϕ < 0.4), increasing ionic strength hardly affects the relative viscosity whereas at higher particle volume fractions, a decrease in viscosity is observed due to a reduced range of electrosteric repulsion between particles, corresponding to a reduction of the effective particle volume fraction ϕeff. For dispersions including attractive interactions, at volume fractions ϕ = 0.45 below the hard sphere freezing point (ϕc=0.5), independently of the ionic strength, the bulk viscosity increases monotonically with increasing PEO concentration due to the transition from a fluid to a fluid/crystalline and finally to a gel state. However, the increase in ionic strength shifts the concentrations of both phase transitions to lower polymer concentrations, indicating that in presence of salt a weaker attraction is required to induce these transitions. At ϕ=0.52, just above ϕc, for dispersions without added salt, broadening of the fluid-crystalline coexistence regime, due to added PEO, results in a viscosity minimum corresponding to different size and packing density of the crystalline regions as observed earlier in Weis et al. [1]. When salt is added, the initial state for dispersions without PEO is a fluid state due to the reduction of ϕeff and the addition of a small amount of PEO leads to an increase in bulk viscosity due to the formation of large crystals for dispersions containing 10 mM NaCl and a network of small, dense crystals of size ≈10 µm when 100 mM NaCl is added. At ϕ=0.54, a result similar to ϕ=0.52 is obtained for dispersions without added salt, whereas in presence of salt, we find that the fluid/crystalline coexistence regime narrows down as the range of electrosteric repulsion decreases and the addition of PEO results in gel formation and gels become more uniform with increasing attraction strength. These investigations demonstrate how superimposed short range electrosteric repulsion and weak depletion attraction affect microstructure and flow behavior of colloidal dispersions.

Effect of particle volume fraction on wear behavior in Al–SiC MMC coated on DIN AlZnMgCu1.5 alloy

Abstract In this study, DIN AlZnMgCu1.5 alloy surface (Al + SiC) was coated with metal matrix composite (MMC) by using hot press sintering method (HPSM). Al was used as matrix material and SiC powders were used as reinforcing material in the coating process on DIN AlZnMgCu1.5 alloy surface. Al/SiC MMC coating was produced at 600 °C under 120 MPa pressure and with varying SiC content (5, 10 and 15 vol.%). Optical microscopy (OM), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), and X-ray diffraction (XRD) were used to examine the microstructure, elemental analysis and phase structure of both the coating zone and the transition zone between the substrate and the coating. The hardness was measured and a dry sliding linear reciprocating wear test was run to determine the mechanical properties of the coating layer. Consequently, the coefficient of friction (COF) and wear volume were determined. OM and SEM images showed a homogeneous distribution of SiC particles and a less porous structure. The hardness of the MMC coating increased with increasing SiC content. Also, the numerical analysis of the wear test simulation was done based on Archard’s law. The results of both wear tests showed that the volume loss values were consistent with each other and the amount of wear significantly reduced by increasing the rate of SiC reinforcement.

Experimental investigation and numerical simulation of relative permeability modifiers during water shut-off

Relative permeability modifier (RPMs) is a water-shutoff technique that is implemented mostly in high water-producing wells when conventional mechanical isolation methods are not suitable. To optimize RPM injection treatment, numerical simulation is the most effective tool. In this study, laboratory experiments were conducted to investigate the rheology and characteristics properties of newly formulated polymer grafted bentonite (GB). Baseline GB dispersion rheological model was developed using the concept of the effective volume fraction of particles, which depends on hydrodynamic forces. The model considers the effects of the three most significant factors, namely concentration, shear rate, and temperature. GB was then tested in a coreflood to ensure effectiveness and applicability in real reservoir conditions. Coreflood results were matched using a numerical simulator and the rheology model was incorporated to reduce uncertainty and determine critical GB-related simulation parameters. Subsequently, a pilot-scale simulation, which uses the history-matched coreflood parameters, was built to predict and optimize 5-spot pattern performance. A sensitivity analysis was performed for the effect of GB volume injected, layer thickness, and permeability contrast. The results show that the viscosity equation resulting from the modeling allows appropriate correlation of the experimental data of shear stress versus shear rate with change in concentration and temperature. The simulation results reveal that the injection of GB has improved pilot-scale performance in both water-cut reduction and oil recovery. Sensitivity results indicate that the effective period of GB treatment is longer when treated in low water cut than in high water cut. However, more GB injection results in better water control.

Analysis of the thermodynamic characteristics of particle reinforced multifarious compositions

The mechanical characteristics of particle-reinforced multifarious compositions are virtually hinged on the characteristics of matrix materials, particles, and the characteristics of the interface between particles. The composite material can be used to improve the disadvantages of a single raw material and expand the scope of application. Multifarious compositions have the advantages, such as high specific strength, high fatigue resistance, and high specific stiffness. For this reason, it is widely and specifically used in aviation manufacturing, aerospace technology, and transportation. Composite materials, titanium alloy, aluminum alloy, and alloy steel have become the main structural materials for aircraft body manufacturing, which is conducive to the improvement of fuel efficiency, simplifying system installation, and shortening assembly time. This research introduces a three-phase theoretical model to analyze the thermodynamic characteristics of particle-reinforced multifarious compositions. The effects of particle volume fraction, particle shape, and interface layer thickness on particle thermodynamic characteristics are analyzed and described.

Interparticle and Brownian forces controlling particle aggregation and rheology of silicate melts containing platinum-group element particles

We study the rheology of silicate melts containing platinum-group element (PGE) particles. They exhibit a shear-thinning behaviour, an intense aggregation tendency, and an anomalously high apparent viscosity in the low shear rate limit, even at very low particle volume fraction. Using a compilation of published experimental data, we analyse these effects in three steps. Firstly, we observe that the viscosities of these suspensions are much higher than those of natural silicate crystal-bearing melts for low shear rate regimes. Secondly, we demonstrate that the viscosities at low shear rate limit cannot be estimated by classical rheological models but rather may be understood as the result of particle aggregation, trapping dead fluid, and thereby increasing the effective particle volume fraction. Finally, we scale the critical shear rates for shear-thinning using a Peclet number analysis—invoking a competition between random thermal particle motion and hydrodynamic shearing motion—and, using an empirical extension, we additionally account for the particle–particle interaction energetics. We propose a framework in which the rheology of this family of particle-bearing melts can be predicted, and demonstrate that at low Peclet numbers, PGE-bearing particle aggregation is driven by interparticle forces and Brownian motion.

Particle–liquid transport in curved microchannels: Effect of particle volume fraction and size in Dean flow

Microfluidic transport in spiral channels is a promising flow-driven mechanism for applications such as cell sorting and particle focusing. Spiral channels have unique curvature-driven flow characteristics that trigger Dean flow, forcing the liquid to be displaced toward the outer wall of the microchannel due to centrifugal force. Despite the growing popularity of these applications, there is a lack of physical understanding of such particle–fluid two-phase transport in a spiral microchannel. To address this gap, in this paper we employ a coupled particle-transport-microfluidic-flow (two-phase) computational fluid dynamics model for probing such two-phase transport in a curved microchannel that gives rise to Dean flow. Our simulations reveal that the presence of the particles has two effects: (1) they reduce the Dean flow effect of skewing the flow field toward the outer wall, that is, the flow becomes more symmetric (or the velocity maximum moves toward the center of the channel) and (2) there is a significant alteration in the vortex patterns associated with the Dean flow. We quantify the drag and lift forces experienced by the particles and propose that the corresponding particle-imparted drag and the lift forces on the continuous phase counter the effect of the curvature-driven centrifugal force on the continuous phase, thereby altering the Dean flow characteristics. Furthermore, we anticipate that such precise quantification of the forces experienced by these particles, present in finitely large concentration in microfluidic Dean flow, will be critical in designing Dean flow effect driven size-based microfluidic particle separation.

Discrete element modeling of strongly deformed particles in dense shear flows

The discrete element method (DEM) proposed by Cundall and Strack [1] is a widely used numerical approach to study the fundamentals of particulate matter at the particle scale. In our present study, the flow behavior of dense configurations of soft particles was studied by means of a new formulation of the multi-contact force closure for the DEM. The first step was to verify the response of the new force closure, and calibrate its parameters based on a comparison of the results for simple uniaxial compression with results from a reference simulation. This reference simulation used a highly accurate nonlocal formulation of contact mechanics in the quasi-static limit [2], which accounts for the interplay of deformations due to multiple contact forces acting on a single particle. The newly developed and calibrated model results show significant improvement over those derived via the existing multi-contact model. Also, the dependence of the stress in the sheared granular matter on the Poisson's ratio was unveiled when using the newly derived advanced multi-contact force closure. Therefore, an extensive campaign of simple shear flow simulations was performed (at a fixed volume of the simulation box) to probe the effect of particle volume fraction and the speed of shearing. These simulations show that the stress at particle volume fractions larger than a critical value depends not only on the friction coefficient and particle stiffness, but also on the Poisson's ratio of the material. Finally, we report a response surface for the pressure in a sheared particle bed as a function of all key influence parameters. This response surface is beneficial for calibrating DEM model parameters in extremely dense flow configurations.

Dynamic modeling of particle reinforced composites and its Charpy impact test verification

The placement of particles with complex shapes is one of the difficulties in the modeling of particle reinforced composites. Therefore, a novel modeling method named the velocity-controlled rigid body dynamics method was proposed to establish the geometric model of the particle reinforced composites in ABAQUS/CAE. The method, using rigid particles motion, collision, and separation mechanisms to avoid particles overlapping, can be applied to construct the geometric models of the composites with particles of various shapes. Numerical simulations based on this modeling method and laboratory experiments were adopted to study the effect of particle volume fraction on the impact toughness of ZTA particle reinforced Fe45 matrix composites (ZTAp/Fe45). The results showed that the impact toughness of the composites decreased rapidly to about 1/6 of that of the pure matrix with the introduction of ZTA particles, and then as the particle volume fraction increased, the impact toughness of the composites slowly decreased. The results of the impact tests were consistent with the numerical simulation results, which verified the practicability, validity, and reliability of the algorithm and models.

Extensional Magnetorheology of Viscoelastic Human Blood Analogues Loaded with Magnetic Particles.

This study represents a pioneering work on the extensional magnetorheological properties of human blood analogue fluids loaded with magnetic microparticles. Dynabeads M-270 particles were dispersed in Newtonian and viscoelastic blood analogue fluids at 5% wt. Capillary breakup experiments were performed, with and without the influence of an external magnetic field aligned with the flow direction. The presence of the particles increased the viscosity of the fluid, and that increment was larger when embedded within a polymeric matrix. The application of an external magnetic field led to an even larger increment of the viscosity of the working fluids, as the formation of small aggregates induced an increment in the effective volume fraction of particles. Regarding the liquid bridge stability, the Newtonian blood analogue fluid remained as a Newtonian liquid exhibiting a pinch-off at the breakup time in any circumstance. However, in the case of the viscoelastic blood analogue fluid, the presence of the particles and the simultaneous application of the magnetic field enhanced the formation of the beads-on-a-string structure, as the Ohnesorge number remained basically unaltered, whereas the time of the experiment increased due to its larger viscosity, which resulted in a decrease in the Deborah Number. This result was confirmed with fluids containing larger concentrations of xanthan gum.

Numerical Investigation of the Characteristics of Erosion in a Centrifugal Pump for Transporting Dilute Particle-Laden Flows

Erosion in centrifugal pumps for transporting flows with dilute particles is a main pump failure problem in many engineering processes. A numerical model combining the computational fluid dynamics (CFD) and Discrete Element Method (DEM) is applied to simulate erosion in a centrifugal pump. Different models of the liquid-solid inter-phase forces are implemented, and the particle-turbulence interaction is also defined. The inertial particles considered in this work are monodisperse and have finite size. The numerical results are validated by comparing the results with a series of experimental data. Then, the effects of particle volume fraction, size, and shape on the pump erosion are estimated in the simulations. The results demonstrate that severe erosive areas are located near the inlet and outlet of the pressure side of the impeller blade, the middle region of the blade, the corners of the shroud and hub of the impeller adjoining to the pressure side of the blade, and the volute near the pump tongue. Among these locations, the maximum erosion occurs near the inlet of the pressure side of the blade. Erosion mitigation occurs under the situation where more particles accumulate in the near-wall region of the eroded surface, forming a buffering layer. The relationship between the particle size and the erosion is nonlinear, and the 1 mm particle causes the maximum pump erosion. The sharp particles cause more severe erosion in the pump because both the frequency of particle-wall collisions and the impact angle increase with the increasing sharpness of the particle.

Indentation behavior of metal matrix composites reinforced with arbitrary shape particle using a coupled FE-EFG approach

The effect of particle volume fraction, size, and shape on the indentation behavior of particulate composites is investigated using coupled FE-EFG approach. A systematic approach is presented where the particles are modeled only in a small region under the indenter and the homogenized properties are assigned to the remaining region. Equivalent properties are determined using RVE analysis. Von-Mises criterion along-with updated Lagrangian approach is employed to capture elastoplastic large deformation behavior. Node-to-segment contact algorithm is adopted to model the contact behavior between indenter and matrix. Results in-terms of residual von-Mises stress, equivalent plastic strain, and deformed surface profile are presented.

Numerical simulation of compressible fluid-particle flows in multimaterial Lagrangian hydrodynamics framework

In the numerical simulation of multimaterial flows, Lagrangian method was applied widely, and fluid-particle multiphase flows phenomenon often existed when elastic-plastic material was impacted intensively. Most of the previous studies about the fluid-particle flows in Lagrangian hydrodynamics framework only focused on the dilute flow. It is very necessary to establish a Lagrangian-Lagrangian coupling numerical simulation framework, which is suitable for both multimaterial and dense particle flows in engineering applications. In present study, a numerical model, in which both continuous fluid phase and dispersed particle phase are discretized in Lagrangian frameworks, is developed. In this model, the effect of particle volume fraction, collision force among particles, interaction and coupling between fluid and particle phases are all considered based on the physical meanings. Therefore it is well-suited to complex multiphase flows including transition between dense and dilute particles flows, and material interfaces and free boundaries in multimaterial flows can be solved spontaneously. The relevant numerical technology and approach are proposed and derived, including fixed background mesh, higher order interpolation function, discetezation of coupling source terms and so on. The above numerical model and approach are integrated to a multimaterial staggered-grid elastic-plastic Lagrangian hydrodynamics code. A series of tests, including single particle transport, shock-induced dense particles bed, and explosive dispersal of solid particles, are used to validate the model. The numerical results show excellent agreement with theoretical solutions or experimental measurements, providing confidence in the proposed numerical model and methods.

Three-dimensional analysis of forced convection of Newtonian and non-Newtonian nanofluids through a horizontal pipe using single- and two-phase models

In this paper, 3D analysis of forced convection of Newtonian and non-Newtonian nanofluids through a horizontal pipe using single- and two-phase mathematical models is performed. The models include the Newtonian single-phase model, non-Newtonian single-phase model, Newtonian two-phase mixture model and finally non-Newtonian two-phase mixture model. The geometry of the problem is a horizontal pipe that is filled with Al2O3/water nanofluid. The effects of particle volume fraction and the Reynolds number on the heat transfer and hydrodynamic characteristics of the flow are examined. Results indicate that for the volume fraction of 0.01, the non-Newtonian mixture model gives more accurate results in comparison with the other models. By increasing the solid volume fraction, the mixture models give a higher heat transfer coefficient in comparison with that of the corresponding single-phase model; however, by comparing the results of Newtonian and the corresponding non-Newtonian models, no meaningful relationship can be obtained. Furthermore, for all the investigated models, the Nusselt number is increased with increasing the Reynolds number.

Effects of iron particles’ volume fraction on compression mode properties of magnetorheological elastomers

The effects of iron particle volume fraction (PVF) on the dynamic compression mode properties of isotropic and anisotropic magnetorheological elastomers (MREs) are experimentally investigated considering wide ranges of excitation frequency (1 Hz to 30 Hz), strain amplitude (2.5% to 20%) and magnetic flux density (0 to 750 mT). MRE samples with three different PVFs (15%, 30% and 45%) were fabricated in the laboratory and a test rig was designed to measure their magneto-mechanical characteristics. The effect of PVF on the loss modulus, denoted as PVF-dampening was substantially higher compared to that on the elastic modulus, denoted as PVF-stiffening. Moreover, PVF effects on compression mode properties of the isotropic MRE were greater compared to the anisotropic MRE, and showed coupled dependence on the excitation and magnetic field conditions. Results revealed that strain-rate stiffening of isotropic MRE increased with increasing PVF while slightly decreased for anisotropic MRE. Besides, strain-softening of both MREs increased with increasing PVF. Results were also suggesting of strong dependence of MR effect on the loading conditions, apart from the PVF. MR effect in view of elastic and loss moduli for isotropic MRE increased with increasing PVF from 15% to 45% at 1 Hz, but at higher frequency they become maximum around 30% PVF, regardless of strain amplitude. Both MR effects for anisotropic MRE, however, become minimum around 30% PVF, irrespective of frequency and strain amplitude. Owing to the observed coupled effects of the loading factors with the PVF, a simple phenomenological model was formulated considering independent functions in PVF, excitation frequency, strain amplitude and magnetic flux density for predicting compression elastic and loss moduli of both MREs. The proposed model required identifications of only six unknown constants, showed reasonably good agreements with the measured data.

An effective model for the thermal conductivity of nanoparticle composites/polymers

In this study, an effective model is proposed to predict the effect of nanoparticle agglomeration on the thermal conductivity of three-phase nanocomposites/polymers. In order to better describe this effect, the concept of agglomeration degree is introduced. The effect of particle volume fraction on thermal conductivity of composites is also studied by considering the interphase and agglomeration degree of particles. First, the relationship between agglomeration degree and particle volume fraction is discussed. Then, the effects of particle volume fraction, agglomeration degree and interphase thickness on thermal conductivity of composites are studied. The obtained results show that the agglomeration degree increases with increasing particle volume fraction. The thermal conductivity of composites increases first and then decreases with increasing particle agglomeration degree, and is also affected by the different thermal conductivity of particles and matrix, and the thickness of interphase.

Effect of Particle Volume Fraction on the Performance of Deep-sea Mining Electric Lifting Pump Based on DEM-CFD

Effect of Particle Volume Fraction on the Performance of Deep-sea Mining Electric Lifting Pump Based on DEM-CFD

Low-velocity impact performance of B4C particle-reinforced Al 6061 metal matrix composites

This study addresses the effects of particle volume fraction on the low-velocity impact behavior of B4C particle-reinforced Al6061 metal matrix composites. For this purpose, Al6061 matrix B4C reinforced metal matrix composite materials were produced by powder metallurgy method. Metal matrix composite samples were produced by hot pressing in B4C particle volume fractions of 0, 5, 10 and 15%. Composite samples were subjected to impact using a drop-weight test device in a velocity of 4.55 m s−1 with 5.045 kg striker. After low-velocity impact tests, samples were cut out for cross-sectional examination and measuring residual central transverse displacements. The results were examined in terms of contact force-time, contact force-displacement, impact energy-time curves as well as residual central transverse displacements. Also, microstructural characterizations before and after the impact tests were performed by the Scanning Electron Microscopy (SEM). It was found that metal matrix composite samples exhibited superior impact energy absorbing capacities than unreinforced material under low-velocity impact conditions. Particle volume fraction had a considerable effect on the impact strength, and thus, the impact energy absorbing capacity in composites improved with increasing the particle volume fraction. While the particle volume fraction increased, the composite structures behaved stiffer. As a result, the peak contact force was increased, and the impact durations were almost decreased. However, Al6061/B4C metal matrix composite materials having 15% volume fraction exhibited best impact performance.

Influence of copper oxide with different morphologies on heat transfer performance of nanofluids

By acting as an ideal working fluid for the improvement of the heat transfer performance, nanofluids can enhance the process of convective heat transfer by adding nanoparticles to working fluids. As nanofluids can significantly improve heat exchange efficiency in the heat exchange systems, they have been studied extensively as a primary research topic in the past two decades. Owing to its good thermophysical properties, CuO is usually used as additive filler for improving the enhanced heat transfer performance of different base fluids. So far, various morphologies and structures of CuO nanoparticles and CuO composites (such as nanowires, nanoblocks, and nanospheres) have been synthesized. However, due to different preparation processes and systems, very few studies have explored the effect of CuO morphology on the enhanced heat transfer of nanofluids under the same conditions. In fact, the study of the influence of nanoparticle morphology and subsequent mechanism is significant for the promotion of its practical applications. Water and ethylene glycol have been the primary focus of traditional research works conducted on the base fluid of nanofluids. However, water and ethylene glycol have low boiling points; therefore, they cannot be exposed to higher temperatures. This limitation causes the devices (used for water and ethylene glycol) to become more prone to wear and corrosion, thereby limiting the wide applications of water and ethylene glycol in industrial production. As compared to water and ethylene glycol, dimethicone has the following advantages: Good thermal stability, non-toxicity, odorlessness, and recyclability. However, the thermal conductivity of dimethicone is too low, thereby leading to lower heat transfer efficiency. Therefore, researchers have tried to increase its thermal conductivity by employing various methods. Experimental studies have shown that the heat transfer performance of nanofluids can be enhanced by the addition of metal oxide nanoparticles having high thermal conductivity. In this study, we prepared CuO nanospheres, CuO nanoflowers, CuO nanorods, CuO nanowires-dimethicone nanofluids in order to verify the effect of CuO morphology on the thermal conductivity of nanofluids. The effects of particle volume fraction and shape on thermal conductivity were also studied. In addition, we carried out an in-depth analysis of its enhanced heat transfer mechanism and theoretical prediction model. The experimental results demonstrated that the structure and morphology of nanomaterials have a significant influence on the thermal conductivity of nanofluids. The increase of volume fraction indicates that there is a nearly linear relationship between thermal conductivity and volume fraction. At the volume fraction of 0.75%, thermal conductivities of CuO nanospheres, CuO nanoflowers, CuO nanorods, and CuO nanowires were 0.155, 0.168, 0.189, and 0.233 W/(m K), respectively. The corresponding thermal conductivities also increased by 7.00%, 16.11%, 51.62% and 60.78%, respectively. Through comparison, we conclude that the thermal conductivity of CuO nanofluids is positively correlated with the aspect ratio of CuO under the same conditions. Through a comprehensive comparison of experimental results and the classical theoretical prediction models, we found out that the Maxwell, Jeffrey, Bruggeman, and Looyenga models can meet the prediction requirements of thermal conductivity of spherical CuO nanofluids. The Hamilton-Crosser model can serve as a better predictor of the thermal conductivity of CuO nanofluids. In addition, we analyzed the heat transfer mechanism of CuO nanofluids. It was found that the higher aspect ratio of CuO nanorods and nanowires helps in increasing the probability of contact with each other. This, in turn, established an optimal condition for the hot carrier transport to achieve a minimum energy loss path, thus building a faster thermal conduction network.

Effect of uniform external magnetic-field on natural convection heat transfer in a cubical cavity filled with magnetic nano-dispersion

Heat transfer in magnetic nano-particle dispersion can be influenced by the presence of external magnetic-field. This paper presents an experimental investigation on effect of external uniform magnetic-field on natural convection heat transfer in magnetite and iron nano-dispersion in a differentially heated cubical cavity. The experiments are conducted between the Rayleigh number range of 4.23×105 to 1.0×107. The study includes experiments and discussion on the corroborating and suppressing effects of thermo-magnetic convection induced by the external magnetic-field on the natural convection heat transfer. Additionally, this study also reports the experimental results and pertinent explanation on the directional effect of magnetic-field on the heat transfer in magnetite and iron nano-dispersion. The paper quantitatively presents the extent of heat transfer depreciation/enhancement in different orientations of the cavity in the presence of magnetic-field. The study also explores the effect of particle volume fraction in magnetic fluid on heat transfer in each case.