Newtonian Fluid Behavior Research Articles

Weakly Compressible Approximation of the Taylor–Green Vortex Solution

ABSTRACTThe Taylor–Green vortex represents an exact solution of the Navier–Stokes equations in . In this work, an approximation of this solution in two spatial dimensions is proposed for weakly compressible flows. These flows are characterized by small compressibility (or, equivalently, by a small Mach number) and are often employed in computational fluid dynamics to approximate the behaviour of incompressible Newtonian fluids. In this framework, the proposed solution is expected to be a useful benchmark for numerical solvers that implement the weakly compressibility approximation. To this end, some numerical examples are reported in the final section of this work.

Computational fluid dynamics investigation of pesticide spraying by agricultural drones

Precise control over pesticide spraying by agricultural drones requires fundamental research of multiphase flow, heat and mass transfer of liquid droplets in downwash flow. In this study, water was used as a carrier agent in pesticide formulations, in which the liquid droplets exhibit a Newtonian fluid behavior. A general computational fluid dynamics (CFD) model that characterizes propeller motion coupled with droplet evaporation and deposition was developed. The downwash flow generated by the propeller rotation was simulated using a multiple reference frame method along with the SST-k-ω turbulence model. Spraying of liquid droplets was simulated using a discrete phase model. The flow model validation was conducted by comparing the simulated velocities with experimental data, and the spray model validation was completed by a comparison of droplet depositions from CFD predictions and experiments. The results indicated that the droplet deposition fluctuates with an increase of propeller speed, and that both temperature and relative humidity affect the droplet deposition. In addition, the relation between the number of particles and the impact velocity was identified quantitatively, impact velocity with respect to particle diameter was predicted, and the effects of surface inclination, surface roughness, and crosswind speed on droplet deposition were analyzed. Moreover, an in-depth discussion about the intrinsic relation between downwash flow and droplet spraying was conducted.

A new higher-order super compact finite difference scheme to study three-dimensional non-Newtonian flows

This work introduces a new higher-order accurate super compact (HOSC) finite difference scheme for solving complex unsteady three-dimensional (3D) non-Newtonian fluid flow problems. As per the author's knowledge, the proposed scheme is the first ever developed higher-order compact finite difference scheme to solve 3D non-Newtonian flow problems. The proposed scheme is fourth-order accurate in space and second-order accurate in time, utilizing only seven adjacent grid points at the (n+1)th time level for the finite difference discretization. A time-marching methodology is employed with pressure calculated via a pressure-correction strategy based on the modified artificial compressibility method. Using the power-law viscosity model, we tackle the benchmark problem of a 3D lid-driven cavity, systematically analyzing the varied rheological behavior of shear-thinning (n = 0.5), shear-thickening (n = 1.5), and Newtonian (n = 1.0) fluids across different Reynolds numbers (Re=1,50,100,200). Both Newtonian and non-Newtonian results are carefully investigated in terms of streamlines, velocity variation, pressure distributions, and viscosity contours, and the computed results are validated with the existing benchmark results. The findings demonstrate excellent agreement with the existing results. It is found that for shear-thinning fluid (n = 0.5), u velocity is higher near the top moving wall than the case of Newtonian (n = 1.0) and shear-thickening fluid (n = 1.5) for all Re values. This extensive analysis, using the new HOSC scheme, not only increases our understanding of non-Newtonian fluid behavior but also provides a robust foundation for future research and practical applications.

UHT A2 milks marketed in Brazil: Physicochemical and electrical characterization, rheological behavior and fatty acid profile

UHT A2 Milk offers a consumption alternative for consumers experiencing intestinal discomfort from consuming dairy products. A2 milk, derived from cows with the A2A2 genotype, does not promote the formation of betacasomorphin-7 (BCM-7). However, little is known about the comprehensive composition of this product, as well as its impact on physicochemical and electrical parameters. This study aimed to investigate potential physicochemical and chemical differences between UHT milk with the A2 β-casein genotype and conventional milk without A2 certification, sourced from brands available in the Brazilian market. Therefore, the physicochemical parameters, rheological behavior, electrical impedance, and fatty acid composition were evaluated. The results indicated that A2 milk had higher density, fat, protein, and total solids content compared to UHT milk without A2 certification. Furthermore, it obtained a higher electrical impedance modulus and lower admittance within the analyzed frequency range (1 kHz a 5 MHz). The UHT milk samples showed Newtonian fluid behavior at both temperatures analyzed (10 and 25 °C). Furthermore, the type of UHT milk (with and without A2 certification) did not significantly influence the absolute viscosity of the samples (p > 0.05) across both commercial brands and temperature. Overall, both types of milk had the same composition of fatty acids, with palmitic acid being the major compound. However, C12:0 and C18:1 cis-7 were more abundant in A2 milk. In this sense, the analytical methods used in this study were able to identify differences in macromolecules and compounds within the lipid fraction in the samples investigated. These analytes are suggested as potential identity markers to evaluate the authenticity of UHT bovine containing only beta-casein of the A2 genotype in its composition.

Formation of Self-Healing Granular Eutectogels through Jammed Carbopol Microgels in Supercooled Deep Eutectic Solvent.

Typically, gel-like materials consist of a polymer network structure in a solvent. In this work, a gel-like material is developed in a deep eutectic solvent (DES) without the presence of a polymer network, achieved simply by adding microgels. The DES is composed of choline chloride and citric acid and remains stably in a supercooled state at room temperature, exhibiting Newtonian fluid behavior with high viscosity. When the microgel (Carbopol) concentration exceeds 2 wt %, the DES undergoes a transition from a liquid to a soft gel state, characterized as a granular eutectogel. The soft gel characteristics of eutectogels exhibit a yield stress, and their storage moduli exceed the loss moduli. The yield stress and storage moduli are observed to increase with increasing microgel concentration. In contrast, the ion conductivity decreases with increasing microgel concentration but eventually levels off. Because the eutectogel can dissolve completely in excess water, it is a physical gel-like material, attributed to the densely packed structure of microgels in the supercooled DES. Due to the absence of networks, the granular eutectogel has the capability to self-heal simply by being pushed together after being cut into two pieces.

Entropy generation analysis and thermal synergy efficiency in the T-shaped micro-kenics

In this work, three different twist angles of a micro helical insert in a T-shaped are studied numerically in order to evaluate the laminar steady flow behavior of Newtonian fluid in chaotic geometry. In the geometries under consideration, thermal mixing behavior is carried out using fluids having two distinct input temperatures. Under the influence of chaotic advection and low rates of Reynolds number, the second law of thermodynamics is controlled in terms of the entropy generation caused by hydrodynamic and thermal processes. The governing equations are numerically solved using the CFD Fluent code. Thus, the micromixer's configuration demonstrated a very significant improvement in mixing degree while minimizing friction and thermal irreversibilities. The synergy coefficient, which depicts the link between velocity and heat transfer in angle form, is analyzed and the results are provided.

New YAC time-fractional derivative approach for water-based hydromagnetic chemically reacting radiative flow of nanofluid with copper nanoparticles past an upright plate

The current article utilizes the novel application of the Yang-Abdel-Cattani (YAC) fractional derivative to analyze the Casson nanofluid flow. Water nanofluid suspended with copper nanoparticles is considered in the flow phenomenon. Primarily, the dimensionless governing equations are converted to a fractional model by using a new description of fractional derivative, i.e. YAC fractional derivative. These fractional equations are then transformed and solved using the Laplace method. Finally, the solutions of these transformed equations are obtained in terms of a series of Prabhakar functions. The comparative results for Newtonian and non-Newtonian fluids are obtained using the analytical solutions and presented in the form of graphs. The effect of the chemical reaction, Casson parameter, radiation parameter, orders of the time-fractional derivative, and magnetic strength on velocity, temperature, and concentration fields is investigated. The fluid behavior of both Newtonian and Casson fluids is analyzed and presented in the form of graphs. Fluid temperature is enhanced by 5.22% with the use of copper nanoparticles with a 4% volume fraction. With the advancement of chemical reaction, the velocity and concentration of the nanofluid are observed to be decreasing.

A numerical analysis of mixing and separating of Newtonian fluids in a channel filled with porous material

Fluid flow through porous media in intricate geometries has been a fascinating and challenging area of study in applied mathematics and engineering. This area has immense significance in several sectors, such as petroleum, food processing, pharmaceuticals, groundwater flow, and nuclear reactors. This research investigates the behaviour of Newtonian fluids in a conduit filled with a permeable medium under combing and separating stream configurations. The finite element method with the Taylor-Galerkin/Pressure-Correction method is applied in the present study. The stream consists of two reversible setups and two unidirectional streams of linear fluids within a channel filled with porous materials, featuring a sudden gap. To obtain steady solutions, a time-dependent numerical approach is employed. The study examines the effect of intensifying inertia, porosity, and variations in flow rates.

Modeling of a Process Window for Tailored Reinforcements in Overmolding Processes

This study explores cost-effective and customized composite applications by strategically placing carbon fiber-reinforced thermoplastics in multi-material designs. The focus is on developing a model for the simultaneous processing of non-reinforced and reinforced thermoplastic layers, with the aim of identifying essential parameters to minimize insert flow and ensure desired fiber orientation and positional integrity. The analysis involves an analytical solution for two layered power-law fluids in a squeeze flow setup, aiming to model the combined flow behavior of Newtonian and pseudo-plastic fluids, highlighting the impact of the non-Newtonian nature. The behavior reveals a non-linear trend in the radial flow ratio towards the logarithmic consistency index ratio compared to a linear trend for Newtonian fluids. While a plateau regime of consistency index ratios presents challenges in flow reduction for both layers, exceeding this ratio, depending on the height ratio of the layers, enables a viable overmolding process. Therefore, attention is required when selectively placing tailored composites with long-fiber-reinforced thermoplastics or unidirectional reinforcements to avoid operating in the plateau region, which can be managed through appropriate cavity or tool designs.

Anisotropic flow physics in diamond microchannels: Design implications for microfluidic rectifiers handling Newtonian fluids

The study explores anisotropic flow behavior in microchannels, which is crucial for advancing microfluidic rectifiers. Specifically, the investigation focuses on the directional flow behavior of Newtonian fluids within diamond-shaped microchannels, a topology holding significant promise across various disciplines. Unlike non-Newtonian fluids, Newtonian fluids lack inherent directional traits, needing high Reynolds numbers for inertial effects necessary for effective rectification in asymmetric flow structures. High Reynolds numbers in microchannels are challenging, but diamond microchannels uniquely exhibit inertial effects even at low Reynolds numbers, yet their potential for designing rectifiers is largely unexplored. The study presents two unique asymmetric diamond microchannel designs and conducts thorough three-dimensional numerical analyses to assess fluid flow across different design parameters. Rectification is quantified through fluid diodicity, demonstrating that configurations with higher width and aspect ratios and shorter lengths produce significant rectification effects. Examining velocity profiles and flow resistances in both directions illustrates irreversible flow physics. Notably, the observed maximum diodicity for the proposed design reaches 1.61 for Newtonian fluids, surpassing most previous designs by 11%–40%. Quantitative relationships between flow resistances in both directions and design variables through regression analysis allow determining flow resistances within ±8% and fluid diodicity within ±7% and ±10%, respectively, based on constant flow rate and pressure drop. These correlations provide valuable insights for the initial design of microfluidic rectifiers using these configurations. The results offer essential guidance for effectively designing microfluidic rectifiers using diamond microchannels in various scientific applications.

Ready-to-use graphene-related material-added multi-grade oils: characterization and performance in car engine working conditions.

The need for energy efficiency is leading to the growing use of additives to enhance the performance of oil in automotive engines. Great interest is focused on nano-additives even if to date there is still no practical use in commercial liquid lubricants. Herein, the potential of industrially scalable and low-cost graphene-related materials (GRMs) as additives to enhance the performance of oil in automotive engines is explored. The use of polyalkylmethacrylate dispersants, the most common key additives to formulate "green technology" lubricant oils liquid-processed GRM, is explored, investigating the role of the lateral size and the chemical analysis in the stability of the lubricant GRM dispersions. Showing the maximum duration of stability and a production method that avoids the use of strong oxidants, rheological tests were then focused on multilayered graphene flakes with sub-micrometre lateral size mixed in two commercial oil grades (5W-30 and 5W-40) under conditions similar to those of engine operation. The addition of such a filler increases the viscosity without affecting the Newtonian fluid behavior, while four-ball tests show a reduction in wear, indicating improved lubrication performance. Finally, preliminary bench-test on a commercial car engine showed increased power output corresponding to enhanced engine efficiency. The results clearly indicate the effective improvement in lubricating commercial oils due to GRM additives.

Flow and Heat Transfer of Micropolar Ferrofluid at Stagnation Point on a Horizontal Flat Plate in the Presence of Magnetic Field and Thermal Radiation

Ferrofluid demonstrates Newtonian or non-Newtonian fluid behaviour depending on the characteristics of ferrofluid. Generally, ferrofluid consists of a stable colloidal suspension of single-domain magnetic particles in a base fluid that can assume non-Newtonian fluid behaviour involving a spin vector and microinertia tensor in flow motion. These two properties possess the theory of micropolar fluid which exhibits microrotational motions and spin inertia in microscopic behaviour. Therefore, this theoretical study is focused to investigate the boundary layer of micropolar ferrofluid flow and heat transfer at the stagnation point on the horizontal flat plate. Magnetite (Fe3O4) nanoparticles and water (H2O) compose in ferrofluid exposed to the magnetic field and thermal radiation is considered. The influences of ferroparticles volume fraction and micropolar parameter on the ferrofluid flow and heat transfer are evaluated mathematically. The partial differential equations have been formulated based on purposed assumptions using Tiwari and Das model and are simplified into ordinary differential equations, which are then solved numerically by Runge-Kutta Fehlberg (RFK45) method. The numerical results of the velocity profile, temperature profile, angular velocity profile, reduced skin friction and reduced Nusselt number are scrutinised in different values of ferroparticles volume fraction and micropolar parameter to estimate the ferrofluid flow and heat transfer. It is found the velocity profile of micropolar ferrofluid flow increases when elevates the ferroparticles volume fraction but decreases when increasing the micropolar parameter. Meanwhile, enlarging ferroparticles volume fraction of micropolar ferrofluid also enhances the temperature profile, reduced skin friction and reduced Nusselt number in the presence of magnetic field and thermal radiation parameter.

Lattice Boltzmann simulation of cavity flows driven by shear and internal heat generation for both Newtonian and viscoplastic fluids

Following our recent investigation [G. Kefayati, “Internally heated convection of viscoplastic fluids in enclosures using a lattice Boltzmann method,” Phys. Fluids 35, 013108 (2023)], this paper centers on exploring the influence of shear on internally heated convection and its flow within a square cavity. The study delves into the behavior of both Newtonian and viscoplastic fluids within this setup. The cavity features two vertical side walls that consistently maintain low temperatures, serving as isotherms. Meanwhile, the horizontal walls are adiabatic and provide thermal insulation. In this work, we present dimensional macroscopic equations and introduce innovative non-dimensional macroscopic equations. To generate shear, the top lid is continuously translated, and we quantify its intensity using the corresponding Richardson number. For investigating the viscoplastic behavior and defining the yielded (fluid) and unyielded (solid) zones, we employ an exact Bingham model, which relies on a unique tensor. To tackle the problem effectively, we develop a dimensionless lattice Boltzmann method to derive the specified macroscopic non-dimensional equations and subsequently solve the fluid motion scenario. Throughout the study, we introduce modified non-dimensional parameters, including the introduced yield number (Y), Reynolds number (R) ranging from 0 to 400, Prandtl number (Pr) ranging from 0 to 100, and the modified Grashof number (G) within the range of 104–106. By varying these parameters, we analyze their influence on streamlines, isotherms, and the regions of yield and unyielded zones. The obtained results revealed that shear plays a significant role in influencing fluid flow, heat transfer, and the behavior of the unyielded section within the enclosure.

Altered blood rheology in multiwidth microchannels: Hematocrit and tonicity variation

We present a theoretical model for the characterization of the behavior of Newtonian and non-Newtonian fluids inside a microchannel with segments of different widths. This allows us to find the relation required to have collapsed viscosity curves for different fluids in just one experiment. Diverse experiments have been carried out with our setup. We consider different hematocrit concentration samples as well as samples of blood altered with different solutions in order to modify their tonicity. The data are acquired using microscale electronic detection of a fluid/air front advance. This will disclose different diseases that can be distinguished by the change in the normal rheological characteristics of blood or plasma. The results obtained demonstrate that using our setup and mathematical model, we can both distinguish blood with different concentrations of erythrocytes as well as discriminate when a same sample of blood is non-altered, altered with sodium chloride (NaCl) or de-ionized water (DIW), which emulates the abnormalities in the red blood cells of some pathologies. The results show that DIW causes blood to have more non-Newtonian behavior. On the other hand, NaCl causes the sample to become a hypertonic solution, causing the red blood cells to crenate, causing the blood to have a more Newtonian behavior.

Formulation and Characteristics of Edible Oil Nanoemulsions Modified with Polymeric Surfactant for Encapsulating Curcumin.

Curcumin (Cur) is a beneficial phytochemical with numerous health advantages. However, its limited solubility in oil and poor stability hinder its potential for biomedical applications. In this study, we employed a mixture of food-grade Tween 60, a polymeric surfactant, and Span 60 to adjust the hydrophilic lipophilic balance number (HLBt) and prepared nanoemulsions (NEs) of coconut oil (Cc oil) as carriers for Cur. The effects of HLBt values, surfactant-to-oil ratio, and oil ratio on the physicochemical characteristics of the food-grade oil-NEs were investigated using dynamic light scattering, transmission electron microscopy, differential scanning calorimetry, fluorescence polarization spectroscopy, and viscometry. Increasing the addition ratio of Tween 60 in the NEs, thereby increasing the HLBt, resulted in a reduction in NE size and an improvement in their storage stability. The temperature and size of the phase transition region of the NEs decreased with increasing HLBt. NEs with higher HLBt exhibited a disordering effect on the intra-NE molecular packing of Cc oil. NEs with high HLBt displayed low viscosity and demonstrated nearly Newtonian fluid behavior, while those with lower HLBt exhibited pseudoplastic fluid behavior. Cur was effectively encapsulated into the Cc oil-NEs, with higher encapsulation efficiency observed in NEs with higher HLBt values. Furthermore, the Cur remaining activity was significantly enhanced through encapsulation within stable NEs. The biocompatibility of the Cc oil-NEs was also demonstrated in vitro. In summary, this study highlights the preparation of stable NEs of Cc oil by adjusting the HLBt using Tween 60, facilitating effective encapsulation of Cur. These findings provide valuable insights for the development of Cur carriers with improved solubility, stability, and bioavailability.

Investigating the impact of zinc ion substitution on the rheological properties and hyperthermia potential of cobalt ferrite-based ferrofluids

Zn-substituted cobalt ferrite-based ferrofluids (FFs) were successfully synthesized using a modified co-precipitation method. In this study, we aimed to investigate the heating performance of the synthesized FFs using a resonance coil-based magnetic hyperthermia setup and characterize their viscoelastic behaviour using a magneto rheometer. The crystalline spinel phase with Fd3m (227) symmetry was confirmed through Powder X-ray Diffraction (PXRD. Additionally, Vibrating Sample Magnetometer (VSM) measurements allowed us to analyze the effect of Zn substitution on the room temperature magnetic properties of the FFs. To gain insights into the viscoelastic properties, steady-state rheological measurements were performed. The FFs exhibited non-Newtonian behaviour at low shear rates (<100 s−1) and transitioned to Newtonian fluid behaviour at higher shear rates. Furthermore, we investigated the magneto-viscoelastic behaviour of the FFs across a range of magnetic field strengths (0 to 1 T) using three different fluids. It was observed that the viscosity increased as the field strength increased, which can be attributed to the formation of chain-like structures. The heating efficiency of the FFs was evaluated in terms of Specific Absorption Rate (SAR) using the Initial Slope Method (ISM) and Box Lucas Method (BLM). The SAR values for the FFs exhibited a significant increase with Zn substitution, with the maximum values recorded as 188 ± 8 W/g (ISM) and 212 ± 9 W/g (BLM) for Zn0.4Co0.6Fe2O4, surpassing the SAR value of CoFe2O4 (72 ± 8 W/g, ISM; 92 ± 5 W/g, BLM). To assess biocompatibility, we conducted a cell viability assay using HEK-293 cell lines. The results demonstrated high cell viability (>75%) for Zn0.4Co0.6Fe2O4 at a concentration of 100 µg/ml after a 48-hour incubation period.

Darcy flow of unsteady Casson fluid subject to thermal radiation and Lorentz force on wavy walls: Case of slip flow for small and large values of plastic dynamic viscosity

This article describes the evolution of the velocity slip and heat transfer effects on the magnetohydrodynamic oscillatory flow of Casson fluid in a wavy channel immersed in a porous medium in the presence of thermal radiation. The Casson fluid model is used to describe non-Newtonian fluid behaviour. Analytical solutions to the dimensionless governing equations are compared to the numerical outcomes produced by MATLAB's built-in numerical solver, bvp4c. The effect of various physical parameters on momentum and energy profiles of the Casson fluid is analysed. This report also examines a parametric analysis illustrating the impact of the Nusselt number and Casson parameter. Increased velocity fields result from higher values of the thermal radiation and Casson-Viscous parameters. When thermal radiation increases, the impact of thermal diffusivity and temperature increases, and the Prandtl number suppresses the temperature distribution. Furthermore, one slip parameter decreases the velocity field while the other increases fluid velocity. For various values of viscous and radiation parameter, the variations for skin friction coefficient and Nusselt number occur periodically because of the asymmetric wavy motion. A comparative study is carried out to characterise Newtonian and non-Newtonian fluid behavior by analyzing the velocity for β – small (non-Newtonian fluid) and β – large (Newtonian fluid) values of plastic dynamic viscosity using linear slope regression analysis.

Fatty acid profile and rheological behavior of annatto seed oil (Bixa orellana), cupuassu seed fat (Theobroma grandiflorum), and their blends

Annatto seed oil (ASO) and cupuassu seed fat (CSF) were combined at the ratios: 30:70, 50:50, and 70:30 (% w/w). Their fatty acid profile, nutritional quality, FTIR (Fourier Transform Infrared) spectra, and rheological behavior were evaluated. ASO increased the content of polyunsaturated fatty acids in the blends; whereas CSF conferred higher contents of monounsaturated fatty acids. The blends exhibited low atherogenicity and thrombogenicity indices, suggesting nutritional advantages. The Newtonian fluid behavior and FTIR results suggested that mixing ASO and CSF at different proportions did not affect the functional groups. ASO showed an activation energy value which indicated that this fat viscosity was more sensitive to temperature changes. The Newtonian model proved to be suitable to describe the behavior of samples, according to statistical fit parameters R2, χ2, and RSS. The resulting blends presented improved physicochemical properties and nutritional attributes, indicating their feasibility for the development of new products.

A synergistic effect of zinc oxide nanoparticles and polyethylene butene improving the rheology of waxy crude oil

This research examined the use of 75 nm zinc oxide nanoparticles (nano ZnO) and polyethylene butene (PEB) to decrease the viscosity of Nigerian waxy crude oil. The rheology of the crude oil was assessed by measuring the viscosity and shear stress of samples containing PEB at 500, 1000, 2000, 3000, 4000 or 5000 ppm and nano ZnO at 1, 2, 3 or 4 wt% between 10 and 35 °C at shear rates from 1.7 to 1020 s−1. Rheological modeling indicated that a power law pseudoplastic model was the best fit for the experimental data, giving a regression coefficient of 0.99. The addition of these inhibitors induced Newtonian fluid behavior in the crude samples such that the shear stress-shear rate relationship plots were linear at all temperatures. The optimum concentrations of the inhibitors in this study were 2000 ppm PEB (providing a 33% viscosity reduction) and 1 wt% nano ZnO (providing a 26% viscosity reduction). A combination of these additives at these concentrations provided a synergistic effect and gave a greater viscosity reduction of 41%. This work demonstrates that a blend of ZnO nanoparticles and PEB can improve the flowability of waxy crude.

Delivering β-carotene from O/W emulsion-based systems: Influence of phase ratio and carrier lipid composition

The functional performance of emulsified delivery systems depends on the nature of the ingredients, emulsifier type, bioactive compound, droplet volume fraction, and interfacial tension between the oil and aqueous phases. In this context, this study evaluated the effect of β-carotene incorporation in oil-in-water (O/W) emulsions with different volume fractions of the dispersed phase (20, 40 and 60%) assessing the characteristics and in vitro digestibility of these emulsions, using palm or sunflower oil as the oil phase. The presence of the bioactive compound did not influence the rheological behavior of the emulsions, which presented Newtonian fluid behavior. However, emulsions showed higher mean droplet size with adding β-carotene and increasing the O/W ratio. In general, systems with a higher O/W ratio (40:60 and 60:40) showed excellent kinetic stability due to the limitation of droplet movement caused by the high viscosity, regardless of the oil type. Overall, palm oil emulsions showed better characteristics as delivery systems, such as smaller droplet size, better stability, and less color change after 7 days of storage than sunflower oil emulsions. Furthermore, a higher release of free fatty acids from palm oil emulsions was observed, indicating a more significant action of lipase and bile salts at the droplet interface during in vitro digestion. However, sunflower oil emulsion showed a higher bioaccessibility of β-carotene than those incorporated in palm oil one since the fat crystal network inside the palm oil droplets slowed down the β-carotene diffusion from the droplet core to the interface during the digestion process.