Resulting Droplet Size Research Articles

Modelling the Flow Conditions and Primary Atomization of an Air-Core-Liquid-Ring (ACLR) Atomizer Using a Coupled Eulerian–Lagrangian Approach

The Air-Core-Liquid-Ring atomizer is a pioneering internal-mixing pneumatic atomization technique designed for energy-efficient spray drying of highly viscous liquid feeds with substantial solid contents. However, it can suffer internal flow instabilities, which may lead to spray droplets with a wide variation in diameter. Experimental investigation of how flow conditions mechanistically determine the resulting droplet sizes is hindered by high velocities near the nozzle outlet. Therefore, this study addressed the issue by implementing a numerical model, employing a coupled Eulerian-Lagrangian approach with adaptive mesh refinement, to simulate the breakup of the liquid into ligaments and droplets. Additionally, Large Eddy Simulation was incorporated to replicate turbulent flow conditions observed in experiments. The numerical model demonstrated significant improvement in predicting liquid film thickness, compared to previous work. Additionally, the simulated droplet size distributions mirrored experimental trends, shifting to smaller sizes as pressure increased. Unfortunately, while reduced, there is a persistent underestimation of the lamella thickness and the droplet sizes at 0.2 MPa. In spite of this, the fact that the error propagates between the two phenomena underscores the effective coupling between Eulerian and Lagrangian approaches.

Characterization of β-lactoglobulin adsorption on silica membrane pore surfaces and its impact on membrane emulsification processes

Protein adsorption plays a key role in membrane fouling in liquid processing, but the specific underlying molecular mechanisms of β-lactoglobulin adsorption on ceramic silica surfaces in premix membrane emulsification have not been investigated yet.In this study, we aimed to elucidate the β-lactoglobulin adsorption and its effect on the premix membrane emulsification of β-lactoglobulin-stabilized oil-in-water emulsions. In particular, the conformation, molecular interactions, layer thickness, surface energy of the adsorbed β-lactoglobulin and resulting droplet size distribution are investigated in relation to the solvent properties (aggregation state of β-lactoglobulin) and the treatment of the silica surface (hydrophilization).The β-lactoglobulin adsorption is driven by attractive electrostatic interactions between positively charged amino acid residues, i.e., lysin and negatively charged silanol groups, and is stabilized by hydrophobic interactions. The strong negative charges of the treated silica surfaces result in a high apparent layer thickness of β-lactoglobulin. Although the conformation of the adsorbed β-lactoglobulin layer varies with membrane treatment and the solvent properties, the β-lactoglobulin adsorption offsets the effect of hydrophilization of the membrane so that the surface energies after β-lactoglobulin adsorption are comparable. The resulting droplet size distribution of oil-in-water emulsions produced by premix membrane emulsification are similar for treated and untreated silica surfaces.

Investigation of Water Films Shed From an Airfoil in a High-Speed Flow

Abstract The breakup of liquid films in high-speed flows is found in many applications. These include prefilming air blast atomization found in fuel injectors and shedding of droplet off of airfoils. In this work, a test rig has been developed and applied to study the breakup of water films from the trailing edge of an NACA 0012 airfoil placed in a high-speed air flow. The results provided reflect a new detailed dataset focused on air velocities above 75 m/s. Computational fluid dynamic (CFD) simulations were used to guide the development of the rig and the associated boundary and inlet conditions. In this work, air velocities up to 175 m/s were used with water films between 0.4 cm2/s and 3.6 cm2/s. The water film was introduced onto one surface through a series of 0.5 mm holes separated by 1 mm at a location 35 mm downstream of the leading edge of the vane. High speed video was used to document the sheet breakup behavior from the edge of the airfoil. Image analysis was used to identify the breakup length of ligaments formed. Laser diffraction was used 50 mm downstream of the trailing edge of the vane to determine the droplet size distribution and associated representative average diameters generated. A series of test conditions were run between 50 m/s and 175 m/s using multilevel factorial designed experiments. The results obtained were subjected to analysis of variance to generate correlations for breakup length and droplet representative diameters as a function of the conditions studied. The analysis was conducted on dimensionless versions of the variables studied to help connect the results to the physics of the situation. For example, rather than using air velocity to correlate the behavior, the Weber number (based on gas phase density and velocity) was used owing to its historical ability to describe liquid breakup processes. The results obtained are compared with other studies in the literature, and good agreement was found for the conditions at which a comparison could be made. It is observed that, for the conditions studied, liquid film thickness has little effect on the resulting droplet sizes—especially for the higher air velocity cases studied. The results also illustrate the sensitivity to choice of the characteristic length, which is generally consisted of trailing edge geometry or boundary layer thickness. In contrast, liquid film does influence the ligament breakup length, although the time to break up is less affected. Overall, the correlations developed provide engineering tools to help estimate ligament and drop size behavior for water films shed from airfoils in a high-speed flow.

Experiments and fully transient coupled CFD-PBM 3D flow simulations of disperse liquid-liquid flow in a baffled stirred tank

Liquid-liquid disperse multiphase flow in a baffled tank stirred by a Rushton turbine is investigated by experiments and 3D simulations for different impeller speeds and volume fractions. Droplet size distributions are experimentally measured with an inline shadowgraphic probe and compared with fully transient coupled CFD-PBM simulations using the Eulerian multi-fluid framework, the inhomogeneous Multiple Size Group approach and a statistical turbulence model. The simulation model is assessed by a variation of size class and velocity group numbers, grid resolution and simulation domain extent. The model parameters for the breakup and coalescence kernels are fitted to match the measured droplet size distribution at a selected operation point. A subsequent application to different operation points shows that experimental droplet size trends are captured, albeit aside from the fitting point, deviations to data increase. The resulting droplet size distribution is analyzed by an assessment of the turbulent mixing, breakup and coalescence time scales.

Mass Flow Scaling of Gas-Assisted Coaxial Atomizers

This study aims to derive basic principles for liquid mass flow scaling of gas-assisted coaxial nozzles. Four liquid mass flow steps were investigated in the range of M˙liq = 20–500 kg·h−1, applying four atomizers with similar geometry designed at Weaero= const. High-speed camera and phase Doppler anemometer were utilized to detect the local droplet size distribution. To estimate a reliable measurement plane, a detection method and determination according to the free jet theory was used. The resulting droplet size was analyzed, applying the aerodynamic Weber number, as well as the gas momentum flow. An empirical model was derived out of the measured data, which allows for liquid mass flow scaling when process parameters such as GLR, liquid mass flow, and required Sauter mean diameter are specified. The model was developed as a first step towards liquid mass flow scaling of gas-assisted coaxial atomizers within the investigated range of operating conditions.

Reducing the γ'-Particle Size in CMSX-4 for Membrane Development.

Colloidal emulsions for lipophilic drugs can be fabricated using premix membrane emulsification. The state of the art is the application of membranes made from, for example, polycarbonate or polyester, which, however, are prone to fouling and cause waste, due to the low number of cycles. With the use of metallic membranes made from the nickel based single crystalline superalloy CMSX-4, these key disadvantages are eliminated. However, instead, the pore size and the resulting droplet size distribution need to be adjusted and improved. This can be realized by tailoring the size of the γ′-particles, which is controllable by the time and temperature used during precipitation heat treatment and the quenching method after homogenization heat treatment. Therefore, we utilized different heat treatment protocols, varying the cooling rate (water quenching and air cooling) after homogenization heat treatment and the holding time and temperature during precipitation heat treatment. Then, we investigated the γ/γ′-microstructure, including the γ′-morphology and γ′-particle size. We show that water quenching has a significant impact on the γ/γ′-microstructure and often leads to irregular-shaped and poorly aligned γ′-particles after precipitation heat treatment. In comparison, air cooling, followed by a subsequent precipitation heat treatment, results in well-aligned and cubic shaped γ′-particles and is, therefore, favorable for membrane fabrication. A reduction in precipitation temperature leads to morphology changes to the γ′-particles. A reduction of the holding time during precipitation heat treatment diminishes the γ′-particle growth, resulting in smaller γ′-particles. Additionally, a suitable heat treatment protocol for membrane fabrication was identified with a γ′-edge length of 224 ± 52 nm and well-aligned, cubic shaped γ′-particles.

Design of a 3D interfacial SERS liquid sensing platform based on Au-nanobones for discrimination and quantitation of quercetin loaded nanoemulsions

Characterization, and discrimination between free quercetin and quercetin-loaded nanoemulsions (Q-NEs) are described, as well as the design of a plasmonic metal liquid platform for their quantitation. First, reproducible Q-NEs synthesis using GRAS (Generally Recognized as Safe) components and a low-energy method as phase inversion temperature was used. Q-NEs were fully characterized being the resulting droplet size of 73.1 ± 2.4 nm and 69.7 ± 2.3 nm by DLS and SEM, respectively, with spherical morphology and encapsulation efficiency of 96.5%. Based on UV-Vis, Raman and SERS characterization studies, a discrimination between free quercetin and Q-NEs was achieved. Secondly, a new 3D-platform was developed based on tuned gold nanorods-bone shaped with fitted aspect ratios for Q-NEs quantification without altering its native nanostructure using the enhanced stretching at 1600 cm-1 as analytical signal. The developed plasmonic sensing platform allows to reach intensification factors up to 103 and 105 for the target analyte and methylene blue as Raman reporter, respectively. It was also submitted to an exhaustive evaluation of analytical performance characteristics in terms of linear dynamic range (0.5 – 30 µM), detection limit (0.2 µM) with good precision (RSD = 2.6%). The nanometrological 3D SERS approach was reliably implemented and validated on commercial nutritional supplements containing declared encapsulated quercetin as nanosized formulations by means of a statistical comparison with those ones obtained by a µHPLC-DAD method.

Effect of a Dwell Stage in the Cure Cycle on the Interphase Formation in a Poly(ether imide)/High Tg Epoxy System

Epoxies are inherently brittle materials and to overcome this brittleness, a second microphase (i.e., thermoplastic) is typically added. This modification of epoxy resin using thermoplastics results in reaction-induced phase separating morphologies in the micrometer range. In this study, the influence of the curing history, beyond phase separation, on the interphase formation and final morphology of PEI and the high Tg epoxy system is investigated. Several cure cycles were examined, each with a first dwell temperature ranging from 120 to 180 °C for a given time up to the onset of phase separation (OPS) or up to the 80% degree of cure (80% DOC) and then with a second dwell at 200 °C for 20 min to complete the cure cycle. Hot-stage microscopy experiments were carried out at several first dwell temperatures before final conversion at the second dwell. The morphologies and resulting droplet size distribution at the interphase, after the final cure, were analyzed through scanning electron microscopy. Results showed that the diffusion distance was significantly higher in the case of OPS as compared to the 80% DOC case, particularly at lower first dwell temperatures. This behavior was attributed to the fact that, in the case of OPS, polymeric chains were still in a mobile state and diffused further during the second dwell curing stage, while at 80% DOC, polymeric chains were completely bound but still diffuse due to non-stoichiometric curing. This restricted mobility of polymeric chains after phase separation (80% DOC) resulted in a larger number of smaller droplets as compared to the OPS case.

How surfactants influence the drop size in sprays from flat fan and hollow cone nozzles

Spraying is a widely used method to produce a liquid sheet that breaks up into droplets of a certain size distribution. When spraying simple liquids, it is known which experimental parameters determine the droplet size distribution. For many applications, however, surfactants are added, producing a hitherto unknown effect on the droplet size distribution. Using two generic types of spraying nozzles, we sprayed solutions of different types of aqueous surfactants and measured the droplet size distribution of the sprays. We find that the breakup of surfactant solutions is similar to that of pure water but results in droplets that are smaller. The resulting droplet size distribution can be well described using the predictions for simple liquids provided that we replace the parameter of the equilibrium surface tension with the dynamic surface tension of the surfactant solution at a surface age of 15 ms, which is the characteristic time for destabilization and breakup of the liquid sheet. By rescaling with the mean droplet size, the droplet size distributions of water and sprays with different concentrations of surfactants all collapse onto a single curve that is given by the compound Gamma function found previously for pure liquids.

Influence of the component composition of extinguishing fluids on the droplet distribution in an aerosol cloud

The key challenge in the process is to reliably predict the droplet size distributions of extinguishing liquids after they cover the distances from the drop/spray point to the flame combustion area when using aircraft, sprinkler systems, or high-altitude ground spraying systems. It is sensible to perform a comparative analysis of changes in the size of droplets of typical fire extinguishing composition free-falling or sprayed in a gas medium from a variable altitude. We used the compositions typical of fire-extinguishing systems: bishofite and fire-extinguishing agent solutions, bentonite suspension, foamer emulsion, and water. The variation rate of the average, minimum and maximum sizes of droplets in the aerosol composition was recorded. Experiments were performed with varying spray height and initial droplet size distribution to show significant differences in the resulting droplet size distribution of suspensions, emulsions and solutions. Conditions were established, in which the droplet distribution for different extinguishing compositions remains comparable.

Spatially-resolved characterization of oil-in-water emulsion sprays

When an oil-in-water emulsion is utilized for application in a flat-fan spray, micrometer-sized oil droplets are thought to facilitate hole formation on the spray lamella, leading to an earlier breakup of the spray sheet and an increase in resulting droplet sizes. However, prior work has largely focused on changes to the mean or median droplet size, and has not examined the influence of oil-in-water emulsions on the complete droplet size distribution, as well as other droplet properties such as droplet shape and droplet velocity distributions in flat fan sprays. This study concerns the effects of pressure, spatial location, and application of oil emulsions on the resulting droplet size, eccentricity, as well as velocity distributions, all of which are crucial information in determining the dispersion dynamics of the droplets during the spray applications. Experiments were conducted with a TP6515 nozzle, with the abovementioned droplets information measured using digital inline holography (DIH). Results show that the DIH-inferred volumetric droplet size distributions (VDSD) span widely from sub-100 μm to over 2 mm in size. The application of an oil-in-water emulsion results largely in suppression of smaller droplets, while the VDSD is relatively insensitive to increasing the oil volume fraction beyond a critical level. DIH results are consistent with the observation that smaller ligaments are observed only in the breakup regions for the single-phase water sprays, which break up more violently and earlier than larger ligaments. It is these smaller ligaments that are suppressed in the oil-in-water emulsion, which yield sub-millimeter droplets, some with sizes approaching sub-100 μm dimensions, corresponding to driftable sizes in agricultural settings. Interestingly, the application of oil-in-water emulsion generally decreases the eccentricity more significantly at the center than at the edge of the spray fan. We attribute this decrease to the increase in lamella sheet thickness and thus decrease in characteristic shrinkage rates, consistent with observations of high speed shadowgraphs. In all instances, oil-in-water emulsion droplets have higher velocities than equivalent sized water droplets. We attribute this to the earlier action of the spray breakup process in the oil-in-water emulsion, reduced surface energy generation during breakup (larger droplets), and reduced energy dissipation during breakup with oil-in-water emulsions, leading to increased translational energy after the breakup process. Therefore, it appears that oil-in-water emulsion application simultaneously suppresses small droplet formation and increases droplet velocity, and hence spray penetration in agricultural application.

Preparation of black cumin seed oil Pickering nanoemulsion with enhanced stability and antioxidant potential using nanocrystalline cellulose from oil palm empty fruit bunch

The groundbreaking innovation and industrialization are ushering in a new era where technology development is integrated with the sustainability of materials. Over the decade, nanocrystalline cellulose (NCC) obtained from lignocellulosic biomass had created a great value in various aspects. The abundantly available empty fruit bunch (EFB) in the palm oil industry has motivated us to utilize it as a sustainable alternative for the isolation of NCC, which is a worthwhile opportunity to the waste management of EFB. Taking advantage of the shape anisotropy and amphiphilic character, NCC has been demonstrated as a natural stabilizer for oil-in-water emulsion. In this work, preparation of highly stable Pickering nanoemulsion using black cumin seed oil and NCC was attempted. Black cumin seed oil is a class of plant oil with various nutritional and pharmaceutical benefits. However, its poor solubility could substantially lower the therapeutic effect, and thus, requires a delivery system to overcome this limitation. The role of NCC in the formation of stable Pickering nanoemulsion was investigated. The emulsification process was found crucial to the resulting droplet size, whereas NCC contributed critically to its stabilization. The droplet size obtained from ultrasonication and microfluidization was approximately 400 nm, as examined using transmission electron microscopy. The droplet (oil-to-water = 2:8) has long-term stability against creaming and coalescence for more than six months. The nanoemulsion stabilized by NCC could allow a better absorption by the human body, thereby maximizing the potential of black cumin seed oil in the personal care and food industries.

Effect of gas jet angle on primary breakup and droplet size applying coaxial gas-assisted atomizers

This study investigates the influence of gas jet angle on primary jet breakup and the resulting droplet size distribution for coaxial gas-assisted atomizers. In industrial applications, the gas jet of these atomizers are typically angled towards the liquid jet, whereas in most spray investigations in literature, parallel flow configurations are used. To enable a detailed analysis of the influence of the gas jet angle, three atomizers with angles of 0°, 15° and 30° were examined. Other geometric parameters, such as liquid jet diameter, gas gap width and wall thickness were kept constant. For each atomizer, two gas velocities at constant liquid mass flow were investigated i.e., two gas-to-liquid ratios (GLRs). An additional set of experiments was performed at increased system pressure using three atomizers with identical gas jet angles, but with an adapted gas orifice area in order to keep gas velocity, GLR and momentum flow ratio constant for all pressure levels. Water and a glycerol/water-mixture were applied in order to investigate the influence of liquid viscosity. The primary breakup process was monitored by a high-speed camera, whereas the resulting droplet size was detected using a phase-Doppler anemometer. For all system pressures and liquid viscosities under investigation, a distinct influence of gas jet angle on primary breakup as well as on resulting droplet size distribution was observed for low gas velocity.

Comparison of Central Jet and Annular Sheet Atomizers at Identical Gas Momentum Flows

This study compares three different nozzle flow configurations—central liquid jet with surrounding gas phase, liquid sheet with central gas phase, and liquid sheet with inner and outer gas phases. To guarantee constant velocities, as well as momentum flows at the nozzle orifice, a nozzle with identical orifice areas (a central tube with inner and outer slits) was utilized in the experiments. The influence of gas velocity (GLR), dynamic viscosity of the liquid, and nozzle configuration on the resulting droplet sizes (D32, ID32,m) and primary breakup was investigated at constant liquid mass flow. A high-speed camera (HSC) was used for the detection of primary breakup, whereas droplet size measurements were performed with a phase Doppler anemometer. The variation of nozzle configuration exhibited distinct influence on the resulting breakup morphology and droplet size. Especially, for atomizing high-viscosity liquids, application of sheet configurations led to smaller droplet sizes compared to liquid jet configuration.

Arabinan side-chains strongly affect the emulsifying properties of acid-extracted sugar beet pectins

Pectins extracted from sugar beet pulp are promising additives for the food and beverage industry due to their good emulsifying properties. However, the relationship between molecular structure and emulsifying properties is still not fully understood; thus, systematic optimization of pectin extraction for a better emulsifying activity is not possible. In this study, we assess the underlying relationship between molecular structure and emulsifying properties by linking relevant structural parameters of 43 acid-extracted sugar beet pectins to their emulsifying properties.Sugar beet pectins with distinct structural characteristics were produced by acid extraction using varying conditions. The extracted polysaccharides were used as emulsifying agents in oil-in-water emulsions. Resulting droplet sizes were measured to correlate molecular characteristics with emulsifying properties. Analyses of protein content, degree of methylation, degree of acetylation, mean molecular weights, and trans-ferulic acid contents showed that these parameters affect the emulsifying properties to some degree, but cannot fully explain the differences observed among all pectins. However, a linear correlation between the proportion of neutral sugar side chains and droplet sizes was observed. The influence of galactose (18–30 mol%) was negligible, but increasing amounts of branched arabinans (up to 57 mol% arabinose) positively affected the emulsification result. Based on these results, it can be concluded that particularly branched arabinan side chains play an important role in the sugar beet pectin-based stabilization of emulsions. Thus, the arabinose content appears to be a suitable indicator to estimate the emulsifying properties of acid-extracted sugar beet pectins.

Investigation of local and temporal interfacial shear stress distribution during membrane emulsification

AbstractThe production of high‐quality liquid/liquid emulsions is a key factor in many industrial processes, such as in food or pharmaceutical industries. The premix emulsification process enables the controlled adjustment of fine and narrow distributed droplet sizes. Furthermore, premix emulsification in porous structures is considered a low‐shear process that enables the usage and formulation of shear sensitive media (e.g., proteins). However, the local and time‐dependent stress conditions and stress residence time at the droplet interface during droplet dispersion in micro‐porous structures are still unknown. In this paper, interfacial stress distributions during droplet dispersion in premix membrane emulsification are numerically (computational fluid dynamics, CFD) investigated. Time‐dependent stress conditions and stress residence times at the interface are calculated. The stress conditions are related to the droplet deformation process to identify the main mechanisms for droplet breakup. The results are compared to experimental analysis of the resulting droplet size distribution during emulsion formulation. It has been found that higher shear stresses occur at the pore wall, but lower shear stresses at the liquid/liquid (disperse/continuous) interface are responsible for the droplet dispersion process. The stress residence time shows that lower stresses are present over a longer time compared to higher stresses. This is relevant for the understanding of the dispersion process, but also for the use of shear sensitive media (e.g., proteins as emulsifier).

Effect of width/height of the gap between piston and wall on the performance of a novel small volume emulsification device

The concept of a small volume emulsification device developed by the authors is further studied in the present work. Following suggestions of previous work, five different piston plates with orthogonal edges are constructed to oscillate inside a small cube-shaped cell. The different pistons yield several combinations of gap width and height between the plates and the walls of the cell. Their performance is assessed by performing emulsification experiments over an extensive range of piston stroke frequency and emulsification time for a specific non-coalescing system (fixed oil fraction and surfactant concentration). The resulting droplet size distributions are estimated by microscopy images analysis and by phase separation observations. The combined information from these techniques is necessary in order to register the broad size range of droplets. A semiquantitative analysis of the flow field in the gap reveals that droplet breakage process starts at the laminar boundary layers developed between the piston and the cell walls and allows characterization of this field. A theoretical analysis for the mechanism of droplet breakup is presented. The analysis of experimental results demonstrates that four of the five tested piston plates are appropriate for emulsification regarding the generated droplet size distribution and the choice among them requires additional criteria, e.g. energy requirements.

Towards system pressure scaling of gas assisted coaxial burner nozzles – An empirical model

The present study investigates the influence of system pressure, gas velocity, and annular gas gap width on the resulting droplet size. Three external-mixing twin-fluid atomizers are operated at a constant liquid mass flow. The nozzle geometry is kept similar, except that the annular gas gap width is changed. At every system pressure level (1 – 21 bar), three different gas velocities were investigated by changing the gas mass flow. High-speed camera images are used for observation of primary breakup and discussed with regard to local measurements of droplet size performed by a phase Doppler anemometer. The gas momentum flux as well as the gas momentum flow were applied to describe the atomization process under varying operating conditions. Finally, an empirical model is derived, enabling the system pressure scaling of external-mixing twin-fluid atomizers for the range of gas momentum flow under investigation.

Development of a Pressure Stable Inline Droplet Generator with Live Droplet Size Measurement

For the research on droplet deformation and breakup in scaled high-pressure homogenizing units, a pressure stable inline droplet generator was developed. It consists of an optically accessible flow channel with a combination of stainless steel and glass capillaries and a 3D printed orifice. The droplet size is determined online by live image analysis. The influence of the orifice diameter, the mass flow of the continuous phase and the mass flow of the disperse phase on the droplet diameter were investigated. Furthermore, the droplet detachment mechanisms were identified. Droplet diameters with a small diameter fluctuation between 175 µm and 500 µm could be realized, which allows a precise adjustment of the capillary (Ca) and Weber (We) Number in the subsequent scaled high pressure homogenizer disruption unit. The determined influence of geometry and process parameters on the resulting droplet size and droplet detachment mechanism agreed well with the literature on microfluidics. Furthermore, droplet trajectories in an exemplary scaled high-pressure homogenizer disruption unit are presented which show that the droplets can be reinjected on a trajectory close to the center axis or close to the wall, which should result in different stresses on the droplets.

Effect of Solid Particles on Droplet Size Applying the Time-Shift Method for Spray Investigation

This study investigated the influence of solid particles on primary breakup and resulting droplet size for different process parameters. Two sets of Newtonian fluids (each consisting of one pure liquid and one suspension at the same respective viscosity) were used, for isolated investigation of solid particles on spray formation independent of liquid viscosity. The spray was recorded by a high-speed camera and a SpraySpy® system based on the time-shift effect, while a commonly used Spraytec® laser diffraction analyzer was employed for validation. An external-mixing twin-fluid atomizer was operated at different gas velocities and corresponding GLR at constant liquid mass flow. For the investigated suspensions an increased Sauter mean diameter was detected, compared to the pure liquids with identical dynamic viscosity. This effect was explained by the tensile strength stabilizing the suspension droplets.