Newtonian Fluid Research Articles

Examining laminar, non-stationary viscoelastic fluid flow between two parallel planes

The generalized Maxwell model is used to handle problems involving the unsteady flow of a viscoelastic fluid in a flat channel under the effect of a constant pressure gradient. Formulas for fluid flow, velocity distribution, and other hydrodynamic characteristics were found. Transient processes during unsteady flow of a viscoelastic fluid in a flat channel are investigated based on the discovered formulas. The analysis’s conclusions demonstrated that, at small Debord number values, the procedures of changing a viscoelastic fluid’s properties from an unstable to a stationary state essentially don’t differ from those of a Newtonian fluid. Exceeding the Debord number relatively unity, it has been established that the process of transition of a viscoelastic fluid from an unsteady state to a stationary state is of a wave nature, in contrast to the transition process of a Newtonian fluid, and the transition time is several times longer than that of a Newtonian fluid. It was also discovered that perturbed processes can arise during the transition. These disturbances occurring in unsteady flows of a viscoelastic fluid can be stabilized by mixing the Newtonian fluid within it. The implementation of this property is important in preventing technical failures or malfunctions.

Comparative predictions of turbulent non-isothermal flow of a viscoplastic fluid with yield stress

RANS simulation of turbulent non-isothermal flow in a pipe by transition of Newtonian fluid into a viscoplastic non-Newtonian fluid is carried out. Carrier phase turbulence was modeled using two-equation isotropic k‒ε˜ – model and Reynolds stress transport model. Results of calculations of Newtonian and non-Newtonian power-law fluids were compared with data of DNS calculations of other authors. Comparisons with data from other works for isothermal Schwedoff-Bingham fluid were performed in this work using k‒ε˜ – model. Satisfactory agreement was obtained with data from other studies for the axial averaged velocity and turbulent kinetic energy radial profiles (the difference is up to 15 %). Reynolds stress transport model showed significant anisotropy between streamwise and transverse velocity fluctuations (up to several times) and good agreement with DNS results of other authors. Averaged and pulsation profiles express the indicated transformation of the non-isothermal turbulent flow.

Elasto-inertial instabilities in the merging flow of viscoelastic fluids.

Many engineering and natural phenomena involve the merging of two fluid streams through a T-junction. Previous studies of such merging flows have been focused primarily upon Newtonian fluids. We observed in our recent experiment with five different polymer solutions a direct change from an undisturbed to either a steady vortical or unsteady three-dimensional flow at the T-junction with increasing inertia. The transition state(s) in between these two types of merging flow patterns is, however, yet to be known. We present here a systematic experimental study of the merging flow of polyethylene oxide (PEO) solutions with varying polymer concentrations and molecular weights. Two new paths of flow development are identified with the increase of Reynolds number: one is the transition in very weakly viscoelastic fluids first to steady vortical flow and then to a juxtaposition state with an unsteady elastic eddy zone in the middle and a steady inertial vortex on each side, and the other is the transition in weakly viscoelastic fluids first to a steady vortical and/or a juxtaposition state and then to a fully unsteady flow. Interestingly, the threshold Reynolds number for the onset of elastic instabilities in the merging flow is not a monotonic function of the elasticity number, but instead follows a power-law dependence on the polymer concentration relative to its overlap value. Such a dependence turns out qualitatively consistent with the prediction of the McKinley-Pakdel criterion.

Dissipation in nonequilibrium thermodynamics and its connection to the Rayleighian functional

We examine quantitatively the role of dissipation in nonequilibrium thermodynamics and its connection to variational principles and the Rayleighian functional. The extremum of the Rayleighian is sometimes used to describe the inertialess (dissipation-dominated) dynamics of continuum systems, and it has been applied recently for the modeling of soft matter dynamics. We discuss how dissipation is considered within one of the modern complete descriptions of nonequilibrium thermodynamics, namely the single generator bracket formalism. Within this formalism, dissipation is introduced through the use of the dissipation bracket, describing irreversible dynamics, which is added to a Poisson bracket that describes the reversible dynamics of the system. A possible connection with the Rayleighian functional is then demonstrated that in all cases considered herein, the Rayleighian is equal to minus one half of the effective dissipation rate of the Lagrangian functional. The effective dissipation rate is obtained starting with an inertial (i.e., flux-based or velocity-based) system description, involving the Poisson bracket and the primitive part (i.e., without the entropy correction term) of the dissipative bracket. Several examples are discussed in detail, ranging from an algebraic model (damped oscillator) to continuum ones: modeling of fluid flow in porous particle media, viscous Newtonian compressible and incompressible fluid flows, and more interestingly, flow of a nematic liquid-crystalline material.

Numerical way out through finite volume method for Navier-Stokes type blood flow inside stenosed curved arteries

This article explores the intricate fluid dynamics within stenosed curved arteries, focusing on Newtonian or viscous fluids' incompressible, two-dimensional, and time-independent flow. The modeled Navier-Stokes equations in curvilinear coordinates are solved numerically through the finite volume method by using open foam, and exact solutions are also computed after using the assumptions of mild stenosis. The flow inside a stenosed curved artery having computational results through FVM is the main achievement of the present work. We have included 2D and 3D graphics depicting pressure gradient, velocity distribution, and shear stress for physical visualization. This helps provide a clear understanding of the physical circumstances exhibited in the analysis. This work contributes significantly to biomechanics by unraveling the intricacies of fluid flow in stenosed curved arteries. The combination of numerical simulations, exact solutions, and visual representations enhances our understanding of the underlying physical phenomena, paving the way for further advancements in cardiovascular research and clinical applications. These visual representations serve as crucial tools for physical visualization, enhancing the interpretability of the complex flow patterns observed in the analysis.

Molecular dynamics simulation and experimental study of the rheological performance of graphene lubricant oil

The microscopic molecular motion behavior between graphene and the liquid lubricant oil affects the rheological and frictional behavior of the nano-lubricant. However, the effect of graphene on the rheological behavior of industrial #3 lubricant oil has not been revealed. Thus, molecular dynamics (MD) and experimental study are used to investigate the effect of graphene concentration, size, temperature, and shear rate on the viscosity, mean square displacement (MSD), and density of graphene lubricant oil are investigated. The results show that the viscosity of GLO increases with the increase of graphene concentration and decreases with the increase of temperature (293 K–330 K). The MSD of graphene lubricant oil decreases with the increase of graphene size and increases with the increase of temperature. It is worth noting that graphene lubricant oil with 3G has the maximum value of MSD, which means the graphene has the best diffusion performance at this concentration. Compared to the base oil, the simulation and experiment viscosity values of the GOL with 3G increased by 22.9 % and 47.6 %, respectively. The GOL has the characteristics of a Newtonian fluid. This study can provide a reference for the application of graphene lubricant oil in industry.

Drop impact dynamics of complex fluids: a review.

The impact of fluid drops on solid substrates has widespread interest in many industrial coating and spraying applications, such as ink-jet printing and agricultural pesticide sprays. Many of the fluids used in these applications are non-Newtonian, that is they contain particulate or polymeric additives that strongly modify their flow behaviour. While a large body of experimental and theoretical work has been done to understand the impact dynamics of Newtonian fluids, we as a community have much progress to make to understand how these dynamics are modified when the impact fluid has non-Newtonian rheology. In this review, we outline recent experimental, theoretical, and computational advances in the study of impact dynamics of complex fluids on solid surfaces. Here, we provide an overview of this field that is geared towards a multidisciplinary audience. Our discussion is segmented by two principal material constitutions: polymeric fluids and particulate suspensions. Throughout, we highlight promising future directions, as well as ongoing experimental and theoretical challenges in the field.

Steady Newtonian fluid flow in nephritis with linear dripping at the walls

Steady Newtonian fluid flow in nephritis with linear dripping at the walls

Oscillatory flow of rheological complex fluid in a flat channel

The article examines the oscillatory flow of rheological complex fluids in a flat channel, in which the rheological complex fluid was obtained based on the Maxwell model, and its mixture is described based on the Newtonian fluid model. Both mixtures of fluids are represented as a homogeneous model of a two-component liquid. In this case, differential equations of motion of homogeneous liquid mixtures are given. Based on this equation, the problem of oscillatory flows of rheological complex fluids in a flat channel is solved analytically. When solving, formulas are given for determining the longitudinal velocity. Using the obtained formulas, graphs of the longitudinal velocity distribution over the cross section of the channel are determined depending on the change in the oscillation frequency parameter, and with their help, appropriate conclusions are drawn.

Electroosmotic flow and heat transfer characteristics of a class of biofluids in microchannels at high Zeta potential

Peristalsis is an important dynamic phenomenon in the field of biomedical research, and has great application prospects in microscale fluids. In recent years, this biomimetic (peristaltic) phenomenon has gained widespread attention due to its large-scale applications in various medical and industrial fields, such as radiation therapy, peristaltic blood pumps, and drug delivery systems. In this study, the electroosmotic flow and heat transfer characteristics are investigated under high wall Zeta potential and slip boundary conditions for a certain type of biological fluid that satisfies the Newtonian fluid model. Fluid flows under the joint action of external electric field, magnetic field, and Joule heating. Firstly, without using the Debye-Hückel linear approximation, the numerical solutions are given by using the Chebyshev spectral method for the nonlinear Poisson-Boltzmann equation, the fourth-order differential equation satisfied by the stream function, and the thermal energy equation. The results are compared with those obtained by using the Debye-Hückel linear approximation to demonstrate the effectiveness of the numerical method used in this study. Secondly, the effects of wall Zeta potential, Hartmann number <inline-formula><tex-math id="M11">\begin{document}$H$\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="6-20231685_M11.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="6-20231685_M11.png"/></alternatives></inline-formula>, electroosmotic parameter <inline-formula><tex-math id="M12">\begin{document}$m$\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="6-20231685_M12.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="6-20231685_M12.png"/></alternatives></inline-formula>, slip parameter <inline-formula><tex-math id="M13">\begin{document}$\beta $\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="6-20231685_M13.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="6-20231685_M13.png"/></alternatives></inline-formula> are discussed on the flow characteristics, peristaltic pumping, and trapping phenomena under electromagnetic environments, and the influence of Joule heating parameter <inline-formula><tex-math id="M14">\begin{document}$\gamma $\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="6-20231685_M14.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="6-20231685_M14.png"/></alternatives></inline-formula> and Brinkman number <inline-formula><tex-math id="M15">\begin{document}$Br$\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="6-20231685_M15.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="6-20231685_M15.png"/></alternatives></inline-formula> is explored on heat transfer characteristics. The results show that 1) wall Zeta potential plays an important role in controlling the velocity of fluid peristaltic flow; 2) the increase of electroosmotic parameter <inline-formula><tex-math id="M16">\begin{document}$m$\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="6-20231685_M16.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="6-20231685_M16.png"/></alternatives></inline-formula> and slip parameter <inline-formula><tex-math id="M17">\begin{document}$\beta $\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="6-20231685_M17.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="6-20231685_M17.png"/></alternatives></inline-formula> increases the flow velocity in the central region of the channel, while the increase of Hartmann number <inline-formula><tex-math id="M18">\begin{document}$H$\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="6-20231685_M18.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="6-20231685_M18.png"/></alternatives></inline-formula> hinders the flow of fluid; 3) these flow behaviors exhibit opposite trends near the channel walls; 4) the number of streamlines captured by peristaltic transport decreases with Hartmann number <inline-formula><tex-math id="M19">\begin{document}$H$\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="6-20231685_M19.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="6-20231685_M19.png"/></alternatives></inline-formula> and electroosmotic parameter <inline-formula><tex-math id="M20">\begin{document}$m$\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="6-20231685_M20.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="6-20231685_M20.png"/></alternatives></inline-formula> increasing; 5) the increase of Joule heating parameter <inline-formula><tex-math id="M21">\begin{document}$\gamma $\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="6-20231685_M21.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="6-20231685_M21.png"/></alternatives></inline-formula> and Brinkman number <inline-formula><tex-math id="M22">\begin{document}$Br$\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="6-20231685_M22.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="6-20231685_M22.png"/></alternatives></inline-formula> leads temperature to rise.

Comparison between Newtonian fluid flow, Stokes flow and Stokes-Oseen flow

Viscosity is an intrinsic property of fluids. It originates in the thermal interactions of molecular collisions. There are two types of it: kinematic viscosity and dynamic viscosity. In this work, we try to model the flow of viscous fluid in three cases: Newtonian fluid flow, Stokes flow and the Stokes-Oseen flow.

Buoyant miscible viscoplastic displacements in vertical pipes: Flow regimes and their characterizations

We experimentally study miscible displacement flows of a light Newtonian fluid by a heavy viscoplastic fluid, in a vertical pipe with a large aspect ratio (δ−1≫1). We use camera imaging, laser-induced fluorescence, and ultrasound Doppler velocimetry techniques, to capture and process data. Four dimensionless parameters, namely, the Reynolds (Re), Bingham (B), viscosity ratio (M), and densimetric Froude (Fr) numbers (or their combinations), mainly govern the flow dynamics. We identify and characterize three distinct flow regimes, including plug, separation, and mixing regimes, while we describe each regime's dynamics in detail, particularly in terms of the velocity and concentration fields as well as the displacement front velocity. In addition, we analyze the plug regime concerning the residual wall layers, the separation regime in terms of the separation dynamics, spatiotemporal separation zone, and viscoplastic layer thinning, and the mixing regime regarding the mixing index and macroscopic diffusion. Finally, we develop a simplified model to help delineate the flow regime classification, in the plane of Re/Fr2 and M.

Ion current rectification properties of non-Newtonian fluids in conical nanochannels.

Ionic current rectification generated by the geometric asymmetry of conical nanochannels has gradually attracted attention, but most studies have been limited to Newtonian fluids. In this study, the ionic current rectification characteristics in conical nanochannels filled with non-Newtonian fluids are investigated by numerical simulations. Electroosmotic flow and ion transport in Sisko fluids are solved using the Poisson-Nernst-Planck equations and the Navier-Stokes equations. The effects of the Debye parameter, power-law indexes and applied voltage on the ionic current, axial potential, ion concentration, radial velocity and rectification ratio in the nanopores are investigated. When κRt = 1, the current rectification ratio increases with the increase of the power-law index. However, when κRt = 6, the current rectification ratio first increases and then decreases with the increase of the power law index, reaching the maximum value at n = 1.0. These findings have positive implications for the construction of some nanodevices such as nanofluidic diodes.

Numerical Investigation of Entropy Generation on Micropolar Trihybrid Nanofluid Flow with Blood as Base Fluid in a Channel

This research paper focuses on investigating the phenomenon of entropy generation, specifically within the context of blood flow. Blood is modeled as a three‐layered liquid model, with micropolar and Newtonian fluids occupying the center and periphery sections of the tube, respectively. A narrow glycocalyx layer adjacent to the wall is regarded as indicating a permeable area caused by the accumulation of carbohydrates and fibrous tissues within the tube wall. Further, the walls of the cylinder are taken as permeable. The objectives of this study include understanding the mechanisms and factors contributing to entropy generation in blood patterns, exploring the relationship between entropy generation and flow characteristics, and analyzing the impact of entropy generation on the overall energy efficiency of the system. The transformation of ordinary differential equations (ODEs) from partial differential equations (PDEs) can be accomplished by employing a similarity approach that combines shooting methods with the inculcation of the RK‐4 method. This integrated technique facilitates the transformation process effectively. Then, MATLAB software is used to plot graphs for accuracy purposes. Under various physical limitations, the comparison study demonstrates that trihybrid nanoliquids exhibit ultrahigh thermal efficiency compared to ordinary nanoliquids, and incorporating these nanofluids enhances entropy generation, temperature, and Bejan profiles, improving thermal conductivity and energy transfer. This integration ensures sustained performance over time, benefiting from carefully selected nanoparticles for stability optimization. As a result, these fluids are extremely useful for industrial applications, particularly filtration and ultrahigh heat.

Aspects of Dual Simulation for Modified Thermal Flux Advances in Non‐Newtonian Reiner–Philippoff Fluid Flow past a Shrinking Plate Embedded in a Porous Medium

This study investigates the effects of non‐Newtonian Reiner–Philippoff fluids on porous media, particularly in the context of steady radiative mixed convection flow and heat transfer near a shrinking plate surface in the presence of magnetohydrodynamics (MHD). The mathematical model is constructed using PDEs and transformed into ODEs via similarity transformations, with numerical solutions obtained using MATLAB’s bvp4c function. The results demonstrate that boundary layer separation occurs slowest for dilatant fluids and fastest for pseudoplastic fluids, with Newtonian fluids exhibiting moderate separation rates. Thermal radiation and media porosity parameters are found to reduce heat transfer by approximately 0.95% and 0.02%, respectively, while accelerating boundary layer separation. Conversely, magnetic effects and suction parameters increase heat transfer by about 0.08% and 4.25%, respectively, enhancing both fluid velocity and temperature. The mixed convection parameter indicates the possibility of dual solutions, with the opposing flow favoring this phenomenon more than the assisting flow. The time‐based stability analysis reveals that the first solution is stable, whereas the second solution is unstable. These findings provide significant insights into the behavior and control of Reiner–Philippoff fluids in practical applications involving porous media and magnetic fields.

Two-relaxation-time lattice Boltzmann model of the velocity profiles and volumetric flow rate of generalized Newtonian fluids in a single-screw extruder

Single-screw extruders and injection molding machines are essential equipment in polymer processing. It is of great importance for the optimization of operating parameters and the design of extrusion screw to predict the throughput of an extruder and the metering time of an injection molding machine according to the geometric parameters of the screw, operating parameters, and the rheological behavior of materials. Most polymer melts exhibit non-Newtonian behavior. The lattice Boltzmann method has many advantages in simulating the flow of non-Newtonian fluids. Herein, the dimensionless velocity profiles and dimensionless volumetric flow rate of generalized Newtonian fluids in a screw channel have been studied using the two-relaxation-time lattice Boltzmann method (TRT–LBM). The numerical results of power-law fluids are in good agreement with the analytical solutions, which verifies the validity of TRT–LBM. Through research, the change rule of the dimensionless volumetric flow rate of Bingham fluids with dimensionless pressure gradient has been obtained. It was found that the rheological properties of polymer melts and the dimensionless pressure gradient significantly affect the dimensionless velocity profiles and dimensionless volumetric flow rate. The dimensionless volume flow rate has some unexpected changes with the increase of the dimensionless pressure gradient. This study can provide theoretical guidance for the optimization of operating parameters and the design of extrusion screws.

Instability of adiabatic shear flows in a channel

The combined forced and free convection flow of a Newtonian fluid in a horizontal plane-parallel channel is examined. The boundary walls are considered as adiabatic, so that the only thermal effect acting in the fluid is the viscous dissipation due to the nonzero shear flow. As the shear flow may be caused by either an imposed horizontal pressure gradient or an imposed velocity difference between the bounding walls, one may envisage two scenarios where the stationary basic flow is Poiseuille-like or Couette-like, respectively. Both cases are surveyed with a special focus on practically significant cases where the Gebhart number is considered as very small, though nonzero. Furthermore, the Prandtl number is assumed as extremely large, thus pinpointing a scenario of creeping buoyant flow with a fluid having a very large viscosity. Within such a framework, the instability of the basic flow is analysed versus small-amplitude perturbations.

EFFECT OF RADIATION AND INJECTION ON A NEWTONIAN FLUID FLOW DUE TO POROUS SHRINKING SHEET WITH BRINKMAN MODEL

This paper is centered on an analytical solution of radiation and injection effects on a Newtonian fluid flow due to a porous shrinking sheet with the Brinkman model. For the momentum equations, the Brinkman model is employed. In addition, the effects of radiation and injection factors on temperature and concentration are considered. Consideration is given to the cross-diffusion relationship between temperature and concentration. By using a similarity transformation, the flow and heat transfer-related coupled partial differential equations are transformed into coupled ordinary differential equations that are non-linear. The exact solutions are obtained for the governing equations analytically. Energy, as well as concentration equations, are solved using the Euler-Cauchy equation method. The accuracy of the method is verified with the existing results, and they are found to be in good agreement. The effect of various physical parameters such as the Darcy number, shrinking parameter, radiation, Soret, and Dufour numbers on non-dimensional velocity, temperature, and concentration profiles have been graphically interpreted. It is found that the velocity profile decreases as the porous parameter increases asymptotically. The temperature increases with an increase in the parameter value of the radiation. The shear stress profile improves when the inverse Darcy value is raised, but it degrades when the suction parameter is moved. Heat transfer rate increases with an increasing Soret number for small values of Dufour number, but it slightly decreases with an increasing Soret number for larger values of Dufour number, and the mass transfer rate reacts in the opposite direction.

An active learning SPH method for generalized Newtonian free surface flows

This paper presents an active learning smoothed particle hydrodynamics (ALSPH) method to simulate generalized Newtonian free surface flows. First, an improved smoothed particle hydrodynamics (ISPH) method is established to obtain more reliable results for free surface flows by coupling the modified kernel gradient, the artificial viscosity, the density diffusive term, and the optimized particle shifting technique. Second, based on data and Gaussian process regression (GPR), an active learning strategy is developed to provide an effective constitutive relation. It is the first time that the ISPH method is combined with GPR to simulate generalized Newtonian free surface flows. Not only can the constitutive relation of any generalized Newtonian fluid in nature be accurately predicted, but a small amount of sampling data is also able to ensure accuracy over a wide range of the shear deformation rate. The challenging droplet impact and dam break are first modeled to validate the ISPH method. Due to the lack of an analytical constitutive relation for an arbitrary generalized Newtonian fluid in nature, the Cross model is then adopted and offers the required data to validate the ALSPH method. The results indicate that the learned constitutive relation is quite consistent with the analytical one and the simulation results match well. In addition, predictive accuracy and time consumption are proven. Furthermore, to verify the applicability of the learned constitutive relation, the jet buckling case and the jet entering the static fluid case are modeled. The good performance demonstrates the ALSPH method has a promising prospect of applications in simulating complex flows in nature.

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.