Viscous Drag Force Research Articles

Smoothed Particle Hydrodynamics simulation of spudcan penetration based on two-phase mixture theory

A novel algorithm was developed based on the two-phase mixture theory within the framework of Smoothed Particle Hydrodynamics (SPH) aiming at simulating the complex soil-water-structure interaction when soil undergoes large deformation. In the algorithm, each constitute is assumed to occupy a certain part of the macroscopic mixture and satisfies its own conservation equations. The soil-water interaction force was composed of pore water pressure and viscous drag force. The spudcan was assumed to be rigid. Frictional sliding contact was employed to modify the momentum equation for particles located near or on the structure surface. With the proposed algorithm, it can investigate the pore water pressure, the effective stress and the porosity for soil undergoing extremely large deformation. Afterwards, its application to the simulation of continuous penetration of the spudcan was presented. The calculated pore water pressure and penetration resistance were compared to the previous research, indicating promising robustness and applicability of the present algorithm. Furthermore, the proposed algorithm could be a potentially efficient tool helping to solve other problems involving soil large deformation and complex soil-water-structure interaction such as deep penetration, underwater excavation, piping and so on, which is quite difficult dealing with traditional mesh-based methods.

Annihilation dynamics of topological defects induced by microparticles in nematic liquid crystals.

The annihilation dynamics of s = ±1 topological defects with and without microparticles in a nematic liquid crystal were investigated and compared. The microparticle with a homeotropic surface anchoring can act as a s = +1 defect and produce a corresponding s = -1 defect nearby. Both of them attract and move towards each other. The speed of the positive defect induced by the microparticle is much slower than that of the negative defect, contrary to the situation without particles. The effects of electric field strength and frequency, particle size, the confining cell gap, and temperature were systematically investigated. The study shows that the dynamics of the annihilation process is related to a complex interplay between elastic attractions, viscous drag forces, backflow effects, director configurations and cell confinement.

Discrete-element model of electrophoretic deposition in systems with small Debye length: effective charge, lubrication force, characteristic scales, and early-stage transport

Electrophoresis was recently proposed as a new method for controlling properties and structure of the interface between cement and steel elements in petroleum and construction industries (Lavrov A et al., 2018). Cement slurries typically contain a wide range of particle sizes (micron to hundred micron), and the particles have small Debye lengths (nanometer). The relative magnitude of different forces acting on particles in such systems was examined. A formulation based on the DLVO theory was used to calculate van der Waals forces and electric repulsion forces between particles. It was shown that the following forces need to be included in a discrete-element model of electrophoretic deposition in this case: viscous drag force, force due to the external electric field, gravity + buoyancy force, lubrication force, van der Waals force, and direct mechanical contact force. The recommended cut-off gaps for van der Waals and lubrication forces are equal to the radius of the larger particle participating in the interaction. An example DEM simulation has revealed that deposition starts with deposing finer particles. Shortly after, larger particles are deposited on the finer substrate. This is due to the larger speed-up time of larger particles. The difference in the speed-up time leads to some size segregation at the early stage of deposition, even though the particle mobility is independent of the particle size. The model enables some insight into the processes that take place during the earlier stages of electrophoretic deposition that are difficult to capture and analyze in laboratory experiments.

Simple shear flow in granular suspensions: inelastic Maxwell models and BGK-type kinetic model

The Boltzmann kinetic equation for low-density granular suspensions under simple shear flow is considered to determine the velocity moments through the fourth degree. The influence of the interstitial gas on solid particles is modeled by a viscous drag force term plus a stochastic Langevin-like term. Two independent but complementary approaches are followed to achieve exact results. First, to keep the structure of the Boltzmann collision operator, the so-called inelastic Maxwell models (IMM) are considered. In this model, since the collision rate is independent of the relative velocity of the two colliding particles, the forms of the collisional moments can be obtained without the knowledge of the velocity distribution function. As a complement of the previous effort, a Bhatnagar–Gross–Krook (BGK)-type kinetic model adapted to granular gases is solved to get the velocity moments of the velocity distribution function. The analytical predictions of the rheological properties (which are exactly obtained in terms of the coefficient of restitution and the reduced shear rate ) show in general an excellent agreement with event-driven simulations performed for inelastic hard spheres. In particular, both theoretical approaches show clearly that the temperature and non-Newtonian viscosity exhibit an shape in a plane of stress–strain rate (discontinuous shear thickening effect). With respect to the fourth-degree velocity moments, we find that while those moments have unphysical values for IMM in a certain region of the parameter space of the system, they are well defined functions of both and in the case of the BGK kinetic model. The explicit shear-rate dependence of the fourth-degree moments beyond this critical region is also obtained and compared against available computer simulations.

Aerodynamic Design of a Solar Road Vehicle

Solar road vehicles have very specific design requirements. This makes their aerodynamic characteristics quite different from classic sedan vehicles. In the present study, the computational model of a typical solar road vehicle was developed to investigate its aerodynamic forces and flow characteristics. Computations were performed assuming the steady viscous flow and using the Reynolds-averaged Navier Stokes equations along with the k-ω turbulence model. The obtained results indicate some important findings that are commonly not present for classic sedan vehicles. In particular, a contribution of the viscous drag force to the overall drag force is considerably larger (41 %) than it is the case for the standard passenger road vehicles, where the form drag force dominates over the viscous drag force. Surface pressure distribution patterns indicate a favorable aerodynamic design of this vehicle. In particular, larger pressure coefficients on the top of the vehicle body as compared to the bottom surface contribute to increasing a downforce and thus the vehicle traction. The airfoil-shaped crosssection of the designed cockpit canopy has favorable properties with respect to reduction of the aerodynamic drag force.

COLLOID-HYDRODYNAMIC REGULATIONS OF THE FLOTATION CHROM (IV) WITH VIOLATION

This paper presents theoretical and experimental studies of the regularities of colloid-hydrodynamic interactions of small particles and a collectively rising air bubble in a model and real system using finely dispersed paraffin as a carrier of BaCrO4 particles. Theoretical studies of the regularities of hydrodynamic interactions of a collectively popping bubble (with a radius of 295 μm) with small particles (with a radius of 3.2 to 12.8 μm) have been carried out. The values of dimensionless criteria were determined with the help of which the efficiency of collision of particles (taking into account their inertia) and the bubble of air rising in water in the transient hydrodynamic regime (Re = 57) was estimated. As a result of theoretical studies of the model of the flotation system, regularities of long-range and near-field hydrodynamic interaction of particles and a bubble are established, which show that the mechanism of such interactions depends on the radius of the particle and its density. It was found that particles with a small radius (from 3.2 μm) and a relatively high density (from 4.5 g/cm3) collide with the bubble surface (as a result of the predominance of inertial forces in the hydrodynamic interaction mechanism) above its equator. In this region, which is unfavorable for fixing particles on the bubble surface, relatively large particles whose density is smaller than the density of the medium also collide, and the radius exceeds 10.9 μm, which is due to the prevalence of viscous drag forces of the medium.It is shown that the extreme nature of the hydrodynamic interactions of particles with a bubble allows us to theoretically justify the optimum amount of carrier for the flotation of small particles. Thus, for example, calculations showed that for flotation of chromium (VI) using finely dispersed paraffin as a carrier, the optimal amount of paraffin corresponds to 7.2 g/g BaCrO4. The experimental values of the capture efficiency of particles by air bubbles, characterizing the joint effect of both hydrodynamic and inertial forces, as well as molecular, electrostatic and other interaction forces arising as a result of surface phenomena in similar colloidal systems are determined. At optimal paraffin consumption (6.3 g/g BaCrO4), the capture efficiency was 1.3×10-3, and the relative capture efficiency (calculated as the ratio of this value to the capture efficiency in the collision without taking into account the hydrodynamic interaction of the particle with the bubble) is 1.8×10-2. The obtained experimental values of capture efficiency agree with the data of the researchers who studied the flotation of small particles without the use of flotation reagents. It has been experimentally established that when about 4.0 g/g of BaCrO4 carrier is added to the system, then chromium(VI) is not flotated at all. A carrier that exceeds the optimum amount somewhat reduces the efficiency of chromium(VI) flotation. Theoretical and experimental data obtained in this paper are in good agreement.

CFD-DEM simulations of particle separation characteristic in centrifugal compounding force field

The separation of particles in centrifugal compounding force field is complex due to the interaction of centrifugal force, viscous drag force, inter-particle contact force and particle-particle collision force. In this work, the CFD-DEM modeling is applied for the first time in the study of particle separation in an innovative centrifugal separator. Some key features of the flow in centrifugal separator are described by using CFD modeling. The DEM is used to model the motion of discrete particles by applying Newton's laws of motion. The particle–fluid and particle–particle interaction forces are examined to explain the separation of particles by density. This approach provides a convenient way to better understand the flow and separation performance of particles in centrifugal compounding force field. Then, a central composite experimental design is used to investigate the relationship between the independent (rotation speed and fluidization water flow rate) variables and the responses (ρ50 and Ep), possible interactions between the independent variables and their effects on the separation performance of the rotation bowl. The results suggest that the fluidization water flow rate have more impact on ρ50 and Ep than rotation speed. The fluidization water flow rate improves the separation efficiency.

Surface Charge Density-Dependent DNA Capture through Polymer Planar Nanopores.

Surface charge density of nanopore walls plays a critical role in DNA capture in nanopore-based sensing platforms. This paper studied the effect of surface charge density on the capture of double-stranded (ds)DNA molecules into a polymer planar nanopore numerically and experimentally. First, we simulated the effective driving force ( Feff) for the translocation of a dsDNA through a planar nanopore with different sizes and surface charge densities. Focus was given on the capture stage from the nanopore mouth into the nanopore by placing a rodlike DNA at the nanopore mouth rather than inside the nanopore. For negatively charged DNA and nanopore walls, electrophoretic driving force ( FEP) under an electric field is opposed by the viscous drag force by electroosmotic flow ( FEOF). As the surface charge density of the nanopore wall becomes more negative, FEOF exceeds FEP beyond a threshold surface charge density, σthreshold, where DNA molecules cannot be driven through the nanopore via electrophoretic motion. For a 10 nm diameter nanopore filled with 1× TE buffer, σthreshold was determined to be -50 mC/m2. The simulation results were verified by performing dsDNA translocation experiments using a planar nanopore with 10 nm equivalent diameter imprinted on three polymer substrates with different surface charge densities. Both fluorescence observation and ionic current measurement confirmed that only nanopore devices with the surface charge density less negative than σthreshold allowed DNA translocation, indicating that the simulated σthreshold value can be used as a parameter to estimate the translocation of biopolymers in the design of nanopore devices.

Morphological transitions of elastic filaments in shear flow

The morphological dynamics, instabilities, and transitions of elastic filaments in viscous flows underlie a wealth of biophysical processes from flagellar propulsion to intracellular streaming and are also key to deciphering the rheological behavior of many complex fluids and soft materials. Here, we combine experiments and computational modeling to elucidate the dynamical regimes and morphological transitions of elastic Brownian filaments in a simple shear flow. Actin filaments are used as an experimental model system and their conformations are investigated through fluorescence microscopy in microfluidic channels. Simulations matching the experimental conditions are also performed using inextensible Euler-Bernoulli beam theory and nonlocal slender-body hydrodynamics in the presence of thermal fluctuations and agree quantitatively with observations. We demonstrate that filament dynamics in this system are primarily governed by a dimensionless elasto-viscous number comparing viscous drag forces to elastic bending forces, with thermal fluctuations playing only a secondary role. While short and rigid filaments perform quasi-periodic tumbling motions, a buckling instability arises above a critical flow strength. A second transition to strongly deformed shapes occurs at a yet larger value of the elasto-viscous number and is characterized by the appearance of localized high-curvature bends that propagate along the filaments in apparent "snaking" motions. A theoretical model for the as yet unexplored onset of snaking accurately predicts the transition and explains the observed dynamics. We present a complete characterization of filament morphologies and transitions as a function of elasto-viscous number and scaled persistence length and demonstrate excellent agreement between theory, experiments, and simulations.

Flow and Heat Transfer in Nanofluid Flow through a Cylinder Filled with Foam Porous Medium under Radial Injection

The Darcy flow and heat convection in nanofluid through a cylinder filled with a foam porous medium subject to local non-thermal equilibrium (LNTE) condition and uniform radial injection on the outer wall of the cylinder is studied. The momentum and two-energy equations are solved by differential transformation method (DTM) in the form of stream function using similarity variables. The effect on flow and heat transfer of different types of nanofluids and involved physical parameters Prandtl number Pr, Reylond number Re, Darcy number Da, Biot number Bi, Ratio of thermal conductivities Rk, porosity parameter ε, solid volume fraction parameter φ and shape of nanoparticles are analyzed through graphs. The viscous drag force and heat convection at the wall of the cylinder is calculated in terms of non-dimensional skin-friction coefficient and Nusselt number respectively. Decreasing the porosity of foam porous medium causes increment in magnitude of heat transfer rate for both the phases. Spherical shape of nanoparticles transfers more heat in comparison of cylindrical shape nanoparticles. Amongst the nanofluid H2O-Ag, H2O-Cu and H2O-Al2O3 the magnitude of heat transfer for fluid phase Nuf is lowest for nanofluid H2O-Al2O3.

Modelling the vertical migration of different-sized Microcystis colonies: coupling turbulent mixing and buoyancy regulation.

Exceptional vertical migration ability provides the cyanobacterium Microcystis with competitive advantages in bloom formation and dominance establishment. Studies have been conducted on the vertical migration patterns of Microcystis since the 1970s; however, bloom simulations remain limited. Here, we used a simple model based on the viscous drag force of turbulence and analysed the motion characteristics of Microcystis colonies. The vertical distribution of turbulent kinetic energy (KZ), cell concentration and colony size profiles in Lake Taihu (Meiliang Bay and Gonghu Bay) and the critical vertical turbulent kinetic energy of colonies (TKZ, i.e. the anti-turbulence ability of colonies) were tested. The results showed that, under steady KZ profiles, colonies had relative rest positions (RRPs) where KZ ≈ TKZ and colonies of the same size gathered together. The vertical migration patterns were affected more by turbulence than by density (colony mass density) if the average KZ of the water column (MKZ) was not equal to TKZ. If MKZ ≈ TKZ, the colonies could exhibit a diurnal pattern of sinking at noon and floating upwards before dawn without steady RRPs. Our results suggest that studies on RRPs may offer optimizations for bloom forecast and control in the future due to easier simulation of KZ profiles than that of flow fields.

Capillarity-Driven Oil Flow in Nanopores: Darcy Scale Analysis of Lucas–Washburn Imbibition Dynamics

We present gravimetrical and optical imaging experiments on the capillarity-driven imbibition of silicone oils in monolithic silica glasses traversed by 3D networks of pores (mesoporous Vycor glass with 6.5 nm or 10 nm pore diameters). As evidenced by a robust square root of time Lucas–Washburn (L–W) filling kinetics, the capillary rise is governed by a balance of capillarity and viscous drag forces in the absence of inertia and gravitational effects over the entire experimental times studied, ranging from a few seconds up to 10 days. A video on the infiltration process corroborates a collective pore filling as well as pronounced imbibition front broadening resulting from the capillarity and permeability disorder, typical of Vycor glasses. The transport process is analyzed within a Darcy scale description, considering a generalized prefactor of the L–W law, termed Lucas–Washburn–Darcy imbibition ability. It assumes a Hagen–Poiseuille velocity profile in the pores and depends on the porosity, the mean pore diameter, the tortuosity and the velocity slip length and thus on the effective hydraulic pore diameter. For both matrices a reduced imbibition speed and thus reduced imbibition ability, compared to the one assuming the nominal pore diameter, bulk fluidity and bulk capillarity, can be quantitatively traced to an immobile, pore wall adsorbed boundary layer of 1.4 nm thickness. Presumably, it consists of a monolayer of water molecules adsorbed on the hydrophilic pore walls covered by a monolayer of flat-laying silicone oil molecules. Our study highlights the importance of immobile nanoscopic boundary layers on the flow in tight oil reservoirs as well as the validity of the Darcy scale description for transport in mesoporous media.

Wall-roughness eddy viscosity for Reynolds-averaged closures

An approach to modeling the effect of rough surfaces on turbulent boundary-layer flow is proposed and developed. It is based on the concept of a rough-wall eddy viscosity, in which the pressure and viscous drag forces which arise on account of flow past roughness elements are recast as an equivalent viscous shear force within the roughness sublayer at the surface. This shear force is modeled as the wall-roughness eddy viscosity and carries information on both the flow Reynolds number and the roughness height. The modeling approach is developed and evaluated as part of a k–ε closure. When the wall-roughness eddy viscosity is modeled in proportion to (ks+)3/4, where ks+=ksuτ/ν and is the sand-grain roughness in wall units, it yields predictions of drag coefficients which are in excellent agreement with those from reference data for flow in rough-walled pipes, over a wide range of surface-roughness heights and Reynolds numbers. Its predictions are also in good agreement with experimental data for zero and favorable pressure gradient boundary layers over fully-rough surfaces.

SPATIAL VIBRATIONS OF A PIPELINE HAVING A SLIDING SUPPORT UNDER THE ACTION OF VARIABLE INTERNAL PRESSURE

This paper studies spatial vibrations of a pipeline having a sliding 'weightless' support under the action of variable internal pressure. The pipeline vibrations occur around an axis running through two supports, one of which is assumed to be immovable and the other slides freely on an ideally smooth horizontal plane. The pipe filled with an incompressible transport medium is surrounded by a viscous incompressible fluid. The internal pressure in the pipe-line is given by the harmonic law. Gravitational forces, Coriolis inertial forces, Archimedes buoyant force, viscous drag forces and those associated with the acceleration of the pipe transverse motion in the surrounding medium are taken into account. In this case the veloc-ity of the transport medium motion, flow friction and linear inertial forces are not taken into account. Deformations of the pipe due to its exit out of the flexure plane are assumed to be small. That is why, spatial vibrational movements of the pipeline are considered to consist of transferable rotational movements around the axis running through the supports and rela-tive flexural displacements in the flexure plane. As a result of these assumptions, the solution to the problem is reduced to integrating a set of two nonlinear partial differential equations describing rotational and flexural vibrations of the pipeline. The function that satisfies the boundary conditions is taken according to the first basic mode. Then using the Bubnov-Galerkin procedure, this set is reduced to two nonlinear ordinary differential equations regarding the bending angle and deflection at mid-span of the pipe in terms of time. The Runge-Kutt numerical method is applied to integrate the resultant set of equations under specific initial conditions. This numerical solution is then subjected to the discrete Fourier transform and Poincare mapping. Calculations were performed for a steel pipeline filled with fluid and gas. The pipeline executed vibrations in air and water media. The magnitude of the average, the amplitude and the initial phase of the internal pressure variable component took the only one value each, and the frequency of this pressure took three values. The computational results are given as time-dependence graphs of the mid-span deflection dynamic constituent, bending angle and sliding support displacement, their phase pattern, Fourier spectra and Poincare maps. The mid-span trajectories are also constructed to give a more visual representation of the pipeline in space over a given time interval.

Comparative study of the dynamic hydrophobicity of fluoroalkylsilane coatings tilted at acute and obtuse angles

The relation between surface homogeneity and internal fluidity for a droplet sliding on a surface tilted at acute and obtuse angles was investigated using two hydrophobic fluoroalkylsilane (FAS) coatings with different roughness. The coatings (FAS-smooth and FAS-rough) were prepared on an Si substrate using chemical vapor deposition or soaking methods and were tilted at 35° or 145°. Sliding velocity of water droplets on the surface tilted at 145° was greater than that tilted at 35° for both coatings. For 35° tilting, the dominant mode of the sliding velocity was slipping for FAS-smooth, whereas rolling governed the entire sliding velocity for FAS-rough. The slipping mode was more important than the rolling one for both coatings when they were tilted at 145°. The change of slipping velocity was more remarkable than that of rolling one for both coatings between 35° and 145° tilting. Results show that the difference in gravity direction and contact area of the droplets contributed to this tilt angle dependence of the sliding velocity. When a droplet slid down with acceleration on FAS-smooth surface, the coefficient of the viscous drag force correlated with the velocity ratio (Utotal/Uslip).

A Triplet Parallelizing Spiral Microfluidic Chip for Continuous Separation of Tumor Cells

Inertial and deformability- based particles separations gradually attract more significant attentions. In this work, we present a hybrid chip by combining the advantages of inertial and deformability –based principle. The chip is a triplet parallelizing spiral inertial microfluidic chip interconnected with numerable tilted slits (Spiral-Slits Chip) for continuous separation of circulating tumor cells. Utilizing the inertial lift and viscous drag forces, different sized particles achieve different equilibrium at distinct streamlines of the spiral microchannel. Numerable tilted slits are organized along the flow direction. They frequently transport segregated streamline particles into a paralleled smaller microchannel. These frequent dragging results in the amount of certain sized particles in the original microchannel gradually and dramatically reduced. Inertial separation of distinct sized particles could be achievable. Two arrays of numerable tilted slits function as bridges. This Spiral-Slits Chip could substitute for Red Blood Cells Lysis (RBCL) and is most effective for ultra-high throughput. The overall arrangement of this triplet parallelizing spiral inertial microfluidic reflects stable streamlines distribution in the first main microchannel. Combining with Ellipse filters, robust and reproducible capture of CTCs could be achieved at high flow rates. Optical absorption detection has been tentatively tested, and this could simplify the process.

Buckling Causes Nonlinear Dynamics of Filamentous Viruses Driven through Nanopores.

Measurements and Langevin dynamics simulations of filamentous viruses driven through solid-state nanopores reveal a superlinear rise in the translocation velocity with driving force. The mobility also scales with the length of the virus in a nontrivial way that depends on the force. These dynamics are consequences of the buckling of the leading portion of a virus as it emerges from the nanopore and is put under compressive stress by the viscous forces it encounters. The leading tip of a buckled virus stalls and this reduces the total viscous drag force. We present a scaling theory that connects the solid mechanics to the nonlinear dynamics of polyelectrolytes translocating nanopores.

Hydrodynamic load modeling and analysis of a floating bridge in homogeneous wave conditions

The Norwegian Public Road Administration (NPRA) is currently developing the E39 ferry-free project, in which several floating bridges will be built across deep and wide fjords. In this study, we consider the floating bridge that was an early concept for crossing the Bjørnafjorden with a width of about 4600 m and with a depth of more than 500 m. The floating bridge concept is a complex end-anchored curve bridge, consisting of a cable-stayed high bridge part and a low bridge part supported by 19 pontoons. It has a number of eigen-modes, which can be excited by wave loads. Wave loads and their effects should thus be properly modeled and assessed. Therefore, the effect of hydrodynamic load modeling are investigated in homogeneous wave conditions, including varying water depth at the ends of the bridge, viscous drag force on pontoons, short-crestedness and second order wave loads. It is found that the varying water depth has negligible effect, while the other features are important to consider. Second order difference-frequency wave loads contribute significantly to sway motion, axial force and strong axis bending moments along the bridge. However, these effects can be reduced by viscous drag forces, which implies that an appropriate model of viscous drag force effect on the pontoons is important. short-crested waves greatly affect the heave motion and weak axis bending moment. All these considerations on hydrodynamic load modeling are further applied to analyze the wave load effect of a floating bridge in a fjord considering inhomogeneous waves [1].

Modulation of the Drag Force Exerted by Microfluidic Flow on Laser-Trapped Particles: A New Method to Assess Surface-Binding Kinetics, Analyte Size, and Solution Viscosity

We have designed and validated a platform capable of assessing minuscule changes of the viscous drag force that different fluid environments exert on individual, micrometer-sized particles. Based on a combination of optical tweezers and a microfluidic device, this platform allows us to expose a laser-trapped particle to a series of microenvironments, created through microfluidic laminar flow, and to monitor biochemical interactions on the surface of the particle. In addition, we can determine the viscosity of the different environments with excellent resolution. We have used this setup to examine the interaction between human IgG and both protein-A as well as protein-G. At saturation, bound IgG added an apparent thickness of 12.6±.77(SD)nm and 16.0±1.4(SD) nm to protein-A- and protein-G-coated beads, respectively. This is in agreement with the expected size of human IgG of ∼10-16 nm dependent on orientation. Moreover, we measured equilibrium constants of KA=4.21x107 M−1 for the protein-A:IgG interaction and KA=7.94x107 M−1 for the protein-G:IgG interaction, in agreement with literature values. Finally, we measured the viscosity of different solutions of bovine serum albumin, human serum, and glycerol with µPa·s resolution. Measurements were performed in a microfluidic flow chamber and in microwells on a glass slide. The microwells allowed us to carry out comparative viscosity measurements with very small volumes of solution, less than 50 µL. The results obtained in each case agree with published models. This platform opens up a new playing field for the study of biochemical surface interactions. Its potential applications include the investigation of biomolecular interactions at the surface of live biological particles, such as individual bacteria, fungal cells, or large viruses, and the determination of the viscosity of costly solutions or small samples.

Transport of emulsions in granular porous media driven by capillary force

The transport of liquids driven by capillary suction-pressure and balanced by both viscous drag force and gravity acceleration is known as spontaneous imbibition. The prediction of spontaneous imbibition in porous media is of importance due to its relevance as a fundamental phenomenon in numerous industrial technologies as well as in nature. A vast majority of the experimental results and mathematical models concerning the imbibition process of single-phase liquids are considered and analyzed in the literature. The present research focuses on two-phase liquids transport in porous medium driven by capillary force. The penetrating liquids were surfactant-stabilized emulsions with the different dispersed phase concentrations. The discussed issues are the influence of porous bed composition and inner phase concentration on the height of an emulsion penetration, which allows to predict the velocity of imbibition process. From a practical point of view, the experimental results give the possibility to evaluate: productivity of granular sorbents applied to recover the environment, efficiency of building materials wetting with multiphase liquids, process of oil-derived pollutants migration in porous media, e.g. soil and other rock structures, etc.