Dilatant Fluids Research Articles

Exploring the Thermal Behavior of Cu-water and CuO-water Power-law Nanofluids on a Rotating Circular Disc: A Computational Analysis

The current theoretical investigation focuses on the thermal behavior of a power-law nanofluid flow on a rotating circular disc. In which nanofluid is made by taking colloidal suspension of copper (Cu) and copper oxide (CuO) nanoparticles in a base fluid like water. A theoretical investigation is conducted by formulating a mathematical model of a power-law fluid (which exhibits shear thickening and thinning effects) along with the Tiwari and Das model. A similarity transformation is employed to transform the nonlinear partial differential equations (PDEs) into ordinary differential equations (ODEs) and these ODEs are then numerically solved using the shooting technique. The study's findings are analyzed graphically by plotting radial, tangential, and axial velocity profiles, temperature profiles, Nusselt number, and skin friction coefficients to show how various factors affect the fluid's flow and heat transfer. It is revealed that drag force reduces in Cu-water nanofluid as compared to CuO-water nanofluid for all types of fluids (Newtonian, pseudoplastic, and dilatant fluids) and Nusselt number becomes high in Cu-water nanofluid for both Newtonian and dilatant fluids as compared to CuO-water nanofluid but in case of pseudoplastic reverse behavior is observed. Heat transfer rate in Cu-water dilatant and pseudoplastic nanofluids increases up to 20.4% and 12.5% with respect to base fluid and in CuO-water dilatant and pseudoplastic water nanofluids, it increases up to 18.6% and 15.2%.

Thermo‐rheological snapshot of melter feed conversion to glass

AbstractSlurry feed charged into an electric melter creates a layer of reacting and melting material (termed cold cap) that floats on the surface of molten glass. The rheological behavior of heated melter feed affects the spreading of slurry at the top of the cold cap and the stability of the primary foam, affecting cold‐cap coverage and melter plenum temperatures. The apparent viscosity of a high‐alumina high‐level waste melter feed was assessed by thermomechanical analysis, high‐temperature viscometer, and the hot stage microscopy method, yielding viscosity estimates from ≈107.5 Pa s at 550°C to ≈102.5 Pa s at 1050°C. As the temperature of feed materials increased, their state changed from rigid solid to dilatant fluid, to pseudoplastic bubbly liquid with dissolving solids, to fully developed foam, and finally to Newtonian glass melt.

Power-law fluid flow in the entrance region between two parallel plates

Flow of non-Newtonian fluids between parallel plates has many uses including heat transfer applications. Many non-Newtonian fluids can be categorized as pseudoplastic fluids. A broader category, power-law fluids, covers in addition dilatant and Newtonian fluids. Models for developing power-law fluid flow between parallel plates include computational and integral boundary layer methods. Most published studies include partial results and apply to one of the three categories. The present work addresses the three cases and exclusively shows the transition from developing to fully developed flow. In the inlet region, viscous effects are restricted to the boundary layer. The present approach is based on the inlet-filled region concept, and includes an additional zone, called filled region in which viscous effects are present in the whole region, with the flow asymptotically reaching the fully developed solution. The integral boundary layer method is used in both regions to solve for the flow. The results are found to be in good agreement with published Newtonian, pseudoplastic and dilatant fluid results for boundary layer thickness, centerline velocity, local friction factor, pressure drop profiles, and entrance region size. The present model is fundamentally analytical with minor computational work required.

Improving the rheological properties of ultra-processed powdered goat milk beverage using texture additives.

This study aimed to investigate the static and dynamic rheological properties of an ultra-processed powdered goat milk beverage containing carboxymethyl cellulose (CMC), guar gum (GG), and xanthan gum (XG), using a mixture design. Fourteen samples were evaluated, in addition to the original beverage. The flow curves classified the fluids as non-Newtonian and characterized all the reconstituted beverages with pseudoplastic behavior, precisely due to the addition of hydrocolloids that increased the viscosity, and the fresh beverage sample showed the behavior of a dilatant fluid. The stress sweep verified the changes in the storage module (G') and the loss module (G″), the G' ranged from 1.97 to 20.36 (Pa) and the G″ ranged from 5.94 to 11.30 (Pa), demonstrating that there was the formation of beverages with elastic and viscous behaviors. The results showed a synergistic effect between the texture improvers, and the formulations with GG identified a greater effect on the tension. The frequency sweep tests showed that the behavior of the samples was that of a weak gel; however, when subjected to a certain frequency, the values of G' exceeded the value of G″, becoming a sample with more elastic characteristics and consequently, presenting the behavior of a stronger gel. Finally, according to the data presented, it is assumed that formulations containing GG and xanthan gum may produce desirable consumer properties for the reconstituted goat milk drink. Samples with a higher concentration of GG exhibited improved rheological performance, characterized by greater consistency, increased resistance to tension, and higher viscosity at low frequencies. PRACTICAL APPLICATION: The powdered goat milk drink is an innovative product that meets the demands of the food industry and consumers by offering a nutritious and sustainable beverage alternative.

Impact of dilating forcing amplitudes on a peristaltically driven non-Newtonian fluid in an elastic tube: application to swallowing disorders

Abstract We investigate the flow dynamics within an elastic tube transporting a power-law fluid, where the tube is subject to a specified external forcing in the form of a progressive traveling wave. The oesophagus is cylindrical in shape and exhibits linear elastic properties. The flow is creeping, and the long wavelength and low Reynolds number approximations are employed for a solution. The relationship between the pressure distribution within the oesophagus and the radial variation of the tube characterizes the behavior of the tube. Findings reveal that the elasticity and the variations in the applied dilating forcing amplitude substantially impact pressure resulting from sinusoidal wave forcing. Notably, even a nominal increase in the inward radial force amplitude for dilatant fluid results in significant pressure changes compared with Newtonian fluid. We also observe a notable distinction between time-averaged volume flow rate and velocity in pseudo-plastic and dilatant forms. Our study also identifies that the radial velocity experiences either attenuation or enhancement due to the fluid’s shear thickening and thinning characteristics. Moreover, our research uncovers a novel dimension by highlighting that in shifting from pseudo-plasticity to dilatancy, the fluid requires higher pressure to propel the bolus toward the hiatus. This observation has important implications, suggesting that feeding a more dilatant fluid to patients with pre-diagnosed swallowing disorders, such as sliding hiatus hernia, is not advisable, fearing increased pressure.

On the stability and accuracy of TRT Lattice-Boltzmann method for non-Newtonian Ostwald-de Waele fluid flows

This paper brings a numerical analysis of the TRT modeling for the Lattice-Boltzmann method when solving flow for dilatant and pseudoplastic power-law fluids. Firstly, the method was reviewed to describe the required simulation parameters and the numerical methodology. Secondly, a mathematical procedure was performed to identify the characteristic relaxation frequency as a function of both flow and fluid properties and to work as a guide parameter for LBM operation. Then, a simple shearing Poiseuille flow was employed so its characteristic shear rate could be calculated as a function of fluid properties, given the flow was characterized by the Reynolds and Mach numbers. For this test case, convergence was then explored for a broad range of parameters, and its non-monotonic dependency on the Mach number for a given convergence criterion was shown. Then, stability maps were constructed based on the characteristic relaxation frequency, which showed a strong dependency between consistency and flow index so the simulation could converge. This was explored against the results from the converged tests, which pointed out the usefulness of the characteristic relaxation frequency in predicting stable solutions. Finally, quantitatively, it was shown that for this power-law fluid flow, the ||L2|| relative error depends on the Mach number to the power of 2(2−n) being now a function of the flow index, extending the previously reported dependency of the Mach number to the power of 2 for plane-Poiseuille flow.

Ultrasonography of Facial and Submandibular Hidradenitis Suppurativa and Concomitance with Acne Vulgaris.

To describe the ultrasound characteristics of facial and submandibular hidradenitis suppurativa (HS) and detect acne vulgaris (AV) concomitance in these cases. We performed a retrospective study of the ultrasound images of patients with facial HS who had been clinically evaluated by dermatologists. The reported ultrasound diagnostic criteria, severity (mSOS-HS), and activity (US-HAS) staging of HS were used to categorize the patients. The finding of fragments of hair tracts within the key lesions (dilated hair follicles, pseudocysts, fluid collections, and tunnels) was considered a pivotal sign to discriminate HS from AV. Demographic and morphological analysis of the images were considered. Thirty-three patients met the criteria (78.8% male/21.2% female). Of these, the mSOS- HS scoring was stage I in 51.5%, stage II in 27.3%, and stage III in 21.2%. Dilation of the hair follicles and the presence of pseudocysts, fluid collections, and tunnels were detected in the HS cases; 63.1% of pseudocysts, 62.4% of tunnels, and 46.2% of fluid collections contained fragments of hair tracts. In all HS cases, there was a key lesion(s) with fragments of hair tracts. Four (12.1%) patients showed concomitant facial HS and acne ultrasound lesions. The acne lesions were pseudocysts without inner hair tract fragments in all cases, and the SOS-Acne scoring was stage II for all of them. Facial HS can be detected on ultrasound and shows a morphology similar to that of HS in other corporal regions. In some cases, facial HS could be concomitant with AV. The subclinical ultrasonographic information can support a better management of these cases.

Analyzing the impact of convective boundary conditions on fluid–particle mixture flow in a ciliated walled horizontal tube filled with Rabinowitsch fluid

This study investigates the impact of convective boundary conditions, thermal radiation, and viscous dissipation on the flow of fluid–particle mixture in a ciliated walled horizontal tube filled with Rabinowitsch fluid. A mathematical model is developed using partial differential equations of continuity, motion, and energy, which are solved using the symbolic software MATHEMATICA 12.0 with convective boundary conditions. Exact solutions for velocity, temperature distribution, pressure gradient, pressure rise, stream function, and heat transfer rate are obtained and analyzed for dilatant, Newtonian, and pseudoplastic fluids. Computational results reveal that the velocity and temperature profiles are highest at the center of the tube for pseudoplastic and Newtonian fluids compared to dilatant fluid. Additionally, pressure gradient fluctuates near the tube walls. The study also explores special cases where the Rabinowitsch fluid model is reduced to dilatant, Newtonian, and pseudoplastic fluids. The findings have potential applications in medical treatments for respiratory system tumors, airway cleaning, physiological fluids, and manufacturing processes involving peristaltic flow. This original research contributes to the understanding of fluid dynamics in complex systems and has implications for various practical applications.

Stability analysis of Reiner–Philippoff nanofluid flow due to sinusoidal waves past a nonuniform channel with Brownian and thermophoretic diffusions

The need for understanding peristaltic flow (PF) is growing frequently because of its applicability in several scientific and technical domains, particularly in biological and medical field. The primary objective of this analysis is to examine the PF in tapering network considering Reiner–Philippoff nanofluid (RPF-NF) under the influence of pseudoplastic fluid (PF) and dilatant fluid (DF) performance. In order to examine the heat and mass transportation inquiry, Buongiorno’s nanofluid model (BNFM) is taken into consideration. The suitable alterations are taken to transform the channel from static reference to stirring frame and, then used the dimensionless variables to transform the moving frame to dimensionless form. Since the Reynolds number (RN) is small and the wavelength is long, the underlying equations are simplified. The statistical consequences are gained through bvp4c technique. The motivation of the physical features on the liquefied crescendos is particularized using graphs as well as tables. For the immovability exploration, eigenvalues are figured. The lowest positive eigenvalues suggest the reliable resolutions; however, the negative eigenvalues denote the unreliable solution. It has been shown that altering the RPF parameter causes the velocity of fluid to switch from a dilatant liquid to a Newtonian fluid and from Newtonian to Pseudoplastic. The results show that the temperature curves ascend with increasing Brownian motion and thermophoretic factors and decrease with increasing Prandtl number. Additionally, a brief mathematical and graphical investigation of the effects of each key parameter on the flow characteristics is conducted.

CFD study of heat transfer in power‐law fluids over a corrugated cylinder

AbstractThe computational study of power‐law fluid flow, along with heat transfer attributes over a corrugated heated cylinder, is explored using ANSYS FLUENT (Version 18.0). Fluids power‐law indices fall in the range of 0.25 ≤ n ≤ 1.5, and the Reynolds number spans in the range of 1 ≤ ReN ≤ 40. The flow is two‐dimensional, steady, and laminar. A wide range of Prandtl numbers (0.7 ≤ PrN ≤ 500) is used to cover the most industrially applied fluids. A domain height of 135Dh is used. A grid with the smallest element size of 0.04 m and 135,914 nodes was used. Flow and heat transfer attributes were studied using streamlines, isotherms, and local and average Nusselt numbers. The average Nusselt number increases with ReN and/or PrN. The heat transfer rate is significantly lower in dilatant fluids and higher in pseudoplastic fluids than in Newtonian fluids. The onset of wake formation behind the cylinder takes place at ReN = 10. The increase in Reynolds number (ReN) and power‐law index (n) causes an increase in wake size. Heat transfer increases with the Reynolds number and/or decrease in the power‐law index. The enhancement in heat transfer due to corrugation is studied in detail in terms of average Nusselt number, which has not been studied for arched corrugated cylinder, even for Newtonian fluids in low Reynolds number range. A Nusselt number correlation is also developed for the given ranges of conditions.

Thermal transport characteristics of fluid-particle suspension in a vertical uniform tube: A computational study on Rabinowitsch fluid with uniform heat source

Problem statement The thermal transport of fluid-particle suspension in Rabinowitsch fluid is discussed theoretically in a vertical uniform tube under the consideration of a uniform heat source. Methodology The fluid and particle phase models are used to develop the mathematical model in the form of partial differential equations which are solved through the symbolic software MATHEMATICA version 12.0 and present the exact solution of temperature distribution, velocity of fluid and particle phases, wall shear stress, pressure gradient, pressure rise, and stream function, etc. Computational results and findings The volume fraction density of the particles slows down the motion of the fluid particles. The velocity of Newtonian fluid is maximum as compared to pseudo-plastic and Dilatant fluids. The fluid phase velocity is superior to particle phase velocity distribution for all pertinent parameters of the analysis. The pressure rise increases in the case of Newtonian and pseudo plastic fluid and decreases in Dilatant fluid. The trapping phenomena are strongly associated with the volume fraction density of the particle. The shear stress shows a decreasing trend against the volume fraction density of the particles, Grashoff number, and heat source parameter. Special case The current fluid model (Rabinowitsch fluid) can be reduced in Newtonian, pseudo plastic, and Dilatant fluid for taking κ → 0 , κ < 0 , and κ > 0 , respectively. Applications The current analysis can be useful in biomedical engineering to observe the blood supply through the arteries, the removal of kidney stones, and also the passage of urine to the bladder from the ureter. Originality The present research is original and has not been published before.

Cross-diffusion and heat transfer effects on peristaltic flow of Reiner-Philippoff nanofluid with pseudoplastic and dilatant fluids over tapered channel: Multiple solutions and stability analysis

Peristaltic flow is used in many scientific and technological fields, including biology and medical technology. The goal of this research is to investigate the peristaltic behavior in an asymmetric non-uniform (tapering) channel using a Reiner-Philippoff fluid model (RPFM)-based nanofluid under the influence of dilatant and pseudoplastic fluid behavior. The Buongiorno nanofluid model (BNFM) is considered to investigate heat mass transportation. The channel is transformed from static reference to movement frame using the subsequent set of modifications, and the dynamic frame is transformed back to dimensionless form using the dimensionless parameters. The fundamental equations have been streamlined due to the long wavelength and small Reynolds number. Novelty of the current study is to examine the stability of numerical framework for RPFM-based nanofluid with dilatant and pseudoplastic fluid behavior. The boundary value problem fourth order code (bvp4c) technique is used to obtain the numerical results. With the use of graphs and tables, the physical elements that influence fluid dynamics are further explained. Stability evaluation has been performed mathematically and graphically. The most reliable solution is shown by the lowest positive eigenvalues, while the unreliable solution is indicated by the negative eigenvalues. It has been proven that changing the Reiner-Philippoff fluid (RPF) factor results in a fluid's velocity changing from dilatant to Newtonian as well as from Newtonian to pseudoplastic. According to the findings, the temperature curves rise as thermophoretic components and Brownian motion increase while decreasing as the Prandtl number increases. A brief theoretical and graphical analysis of each important parameter's effects on the flow dynamics is also carried out.

Microemulsions based on Acer truncatum seed oil and its fatty acids: fabrication, rheological property, and stability

Aims To construct the microemulsion delivery system (ME) loading ATSO and NA and study their physicochemical characteristics to enhance their stability and water solubility. Methods By plotting ternary phase diagrams, the composition and proportions of the MEs were determined. The physicochemical characteristics and stability of MEs were evaluated by mean diameter, polydispersity index (PDI), pH, electrical conductivity, transmission electron microscopy (TEM), rheological behaviour measurement, and phase inversion temperature (PIT). Results The MEs was composed with EL-40 as a surfactant and specifically with the addition of ethanol as a cosurfactant in NA-loaded ME. The mean diameters of ATSO-loaded ME and NA-loaded ME were 39.65 ± 0.24 nm and 32.90 ± 2.65 nm, and PDI were 0.49 ± 0.01 and 0.28 ± 0.14, respectively. The TEM confirmed the spherical and smooth morphology of MEs. The rheological results indicated that MEs are dilatant fluids with the advantages of low viscosity, high fluidity, and tolerance to temperature fluctuations. The mean diameter and PDI of MEs showed no significant change after storage at 25 °C for 28 days and centrifugation. Conclusion The prepared microemulsions could expand the application prospects of ATSO and NA products in cosmetics, medicine, foods and other fields.

Investigation of natural convection and entropy generation of non-Newtonian flow in molten polymer-filled odd-shaped cavities using finite difference lattice Boltzmann method

This study examines the natural convection heat transfer (NCHT) and entropy generation (EG) of a non-Newtonian (NN) flow inside an odd-shaped cavity filled with molten polymer. The cavity configuration comprises hot internal walls, cold external walls, and insulated remaining walls. The finite difference lattice Boltzmann method (FDLBM) is employed to solve the governing equations involved. The input parameters span a range of values, with Rayleigh number (Ra) varying from 104 to 105, power-law index (n) covering a range from 0.5 to 1.5, and width ratio (WR) ranging from 0.2 to 0.4, while maintaining Prandtl number (Pr) at a constant value of 10. The results revealed that at Ra values of 104 and 105, the overall entropy increases as the WR increases from 0.2 to 0.4 and decreases as the n index increases. In contrast to dilatant fluids, where heat transfer (HT) decreases as the n index increases from 1 to 1.5, pseudo-plastic fluids show an opposite trend with HT increasing as the n index decreases from 1 to 0.5. This trend is attributed to the general decrease in the average Nusselt number (Nu) as the n index increases. Additionally, it is observed that the n index has no significant impact on the average Nu due to low buoyancy force at Ra = 104 and WRs of 0.2 and 0.3. However, it notably influences the Bejan number (Be) across all WRs. Overall, the present model demonstrates excellent agreement with previous numerical results, affirming the FDLBM as a superior, reliable, and well-suited technique for relevant applications. These results suggest the potential to extend the application of the FDLBM approach to various cavity shapes, allowing for a comprehensive exploration of NCHT and EG under various conditions.

Hall current effect on molecules motion in viscous non-Newtonian power law fluid with Joule heating and fluxing model of Cattaneo-Christov

This study examines the molecules motion influences and thermal attributes in power-law non-Newtonian dissipative fluids' magnetohydrodynamic behavior, Joule heating, electromigration, and Cattaneo-Christov effects. Effects of Hall on both flow velocity and temperature, as well as the heat transport are considered. The investigation looks at heat transference that occurs when there is a slippage consequence, how the temperature influences the viscosity of the fluid, and how the potential parameters influence the exponential non-Newtonian flow of fluid via an extensible sheet. Runge-Kutta-Fehlberg's approach, which is based on the shooting procedure, was used to develop computational solutions for nonlinear ordinary differential equations. When exposed to a deformation that is generated by expansion, pressure, or agitation, a dilatant fluid is characterized by a phenomenon in which its viscosity rises and may harden. This phenomenon is referred to as the dilatation phenomenon. High shearing rates provide the impression that it is stable. When expanded, subjected to pressure, or agitated, dilatant fluids become more viscous and transform into solids. Both the non-equilibrium that occurs within the fluid and the reduction of the irreversibility processes that occur within it are caused by the acquired charges that are a result of Hall effect of fluid molecules.

A Comparative Study of Newtonian and Non-Newtonian Nanofluids with Variable Thermal Conductivity Over a 3-D Stretching Surface

This study presents a comprehensive numerical and statistical analysis of the flow, heat/mass transfer management of Newtonian and non-Newtonian nanofluid over a bidirectional Darcy-Forchheimer stretching sheet. The external effects of MHD, Joule heating, thermal radiation, heat generation/absorption, Brownian motion, thermal diffusion and chemical reaction are taken into account. It is presumed that the thermal conductivity of fluid varies linearly with temperature. The non-linear coupled P.D.Es are converted into nonlinear coupled O.D.Es using similarity transformation. These equations are solved using MATLAB by implementing four-stage Lobatto IIIa formula and the outcomes of numerous flow parameters are presented graphically. In addition to numerical investigations, a comprehensive statistical analysis is performed using R-software to evaluate the sensitivity of key input parameters towards variable thermal conductivity. The values of local wall friction, local wall heat flux, and wall mass flux for various parameters are tabulated. The study reveals that the heat transmission is significant for dilatant fluids (156.8%) when compared to the pseudoplastic fluids (113.8%). Enriching the values of the Brownian motion parameter suppresses the molecular diffusion while a contrary nature is observed for the thermal diffusion parameter. Further, the mass transfer coefficient shows a very strong negative correlation with variable thermal conductivity parameter for Shear thinning fluids, whereas for Newtonian and Shear thickening fluids it shows a very strong positive correlation.

Pulsating non-Newtonian heat and fluid flow in a concentric annular duct: An analysis using perturbation series method

In the current study, an analytical analysis is conducted to examine laminar pulsating flow and heat transfer of power-law fluid in a concentric annular channel that is uniformly heated. The momentum and energy balance equations are solved analytically using the perturbation series method under the assumption that fully developed hydrodynamic and thermal conditions exist. Nondimensional frequency and amplitude effects on periodic and period-averaged friction factor and Nusselt number are obtained for various power-law index values, representing pseudoplastic, Newtonian, and dilatant fluids. The results from the present study are compared to those from the literature for some specific cases, and an excellent agreement is observed.

Numerical Analysis of Non-Newtonian Fluid Effects on the Equilibrium Position of a Suspended Particle and Relative Viscosity in Two-Dimensional Flow

A solvent in suspension often has non-Newtonian properties. To date, in order to determine these properties, many constitutive equations have been suggested. In particular, power-law fluid, which describes both dilatant and pseudoplastic fluids, has been used in many previous studies because of its simplicity. Then, the Herschel–Bulkley model is used, which describes fluid with yield stress. In this study, we considered how a non-Newtonian solvent affected the equilibrium position of a particle and relative viscosity using the regularized lattice Boltzmann method for fluid and a two-way coupling scheme for the particle. We focused on these methods so as to evaluate the non-Newtonian effects of a solvent. The equilibrium position in Bingham fluid was closer to the wall than that in Newtonian or power-law fluid. In contrast, the tendency of relative viscosity in Bingham fluid for each position was similar to that in power-law fluid.

Interplay of fluid rheology and micro-patterning toward modulating draining characteristics on an inclined substrate

We investigate a gravity-driven thin film flow of a non-Newtonian liquid over an inclined micro-patterned surface. We demonstrate the effect of micro-patterning on the film draining rate and the velocity profile by varying the relative slit width (Tr) and the length of the periodic irregularities (L). We unveil the interplay of the substrate structure and the fluid rheology by modeling the non-Newtonian thin film using the Carreau model, and the rheology of the film is varied for different values of power index n. Through numerical simulations, we delineate the effects of inertia, viscous, and capillary forces on the physics of thin film flow. We report a significant augmentation of flow velocity for both shear-thinning and shear-thickening fluids as a result of substrate micro-patterning, with the relative slit width playing a dominant role while the length of the periodic irregularities has only a minor influence on drainage characteristics. However, when the sole effect of fluid rheology is considered, flow velocity enhances for pseudoplastic fluid and decreases for dilatant fluid in comparison to Newtonian fluid. We examine the combined effect of rheology and substrate topography, revealing the dominating influence of micro-patterning at high slit-widths, while the fluid rheology has a greater role to play at lower slit-widths. We also demonstrate that the susceptibility of flow physics on varying rheology or topography is greatest for low viscosity liquids. Finally, we mark different regimes where the augmentation of average velocity and surface velocity are individually achieved. Hence, we propose a suitable combination of substrate structure and fluid rheology to engineer a flow characteristic. Based on the suitability for various applications, we provide the key to simultaneously optimizing the fluid rheology and substrate micro-patterning for precise engineering and controlling the draining characteristics of a thin film.

Magnetic field effect on mixed convection flow inside an oval-shaped annulus enclosure filled by a non-Newtonian nanofluid

The phenomenon of flow around a static or rotating circular cylinder has significant applications in various engineering fields, such as building, bridge, and structure engineering. It can be used to control flow-induced vibration, blowing or suction, moving surfaces, acoustic thriller, and synthetic jet. Additionally, there is a need to enhance heat transfer rates in many life and industrial applications, including cavity shape enhancement, heating or cooling spread inside a cavity, heat dissipation in electronic devices, thermal mixing in storage units, solar collectors, desalination, and journal bearing lubrication. This study explores the effect of a horizontal magnetic field and a rotating inner circular cylinder on mixed convection within a two-dimensional oval-shaped enclosure filled with a non-Newtonian nanofluid. The Galerkin Finite Element Method (GFEM) is utilized for analysis, with the enclosure undergoing differential heating and cooling on the inner cylinder wall and the enclosure wall, respectively. The nanofluid consists of water infused with copper nanoparticles. The study explores various simulation parameters, including the Richardson number (Ri), Hartmann number (Ha), the inclination angle of the enclosure (β), power-law index (n), circle center eccentricity (e), and nanoparticles volume fraction (φ). It has been observed that as the Ha and n index increase for different Ri values, a wavy trend in local Nusselt number (Nu) profiles along the heat source surface is observed. Additionally, the heat transfer rate decreases with increasing Ri for various combinations of Ha and n index. Under specific conditions, such as Ri = 0.001, Ha = 60, e = 0, φ = 0.09, and β = 90, the results show that, compared to a Newtonian fluid (n = 1), the heat transfer rate exhibits percentage gains of approximately 6.31% for a pseudo-plastic fluid (n = 0.6) and 8.47% for a Dilatant fluid (n = 1.4). The convective heat transfer was significantly enhanced when the eccentricity of the cylinder was positioned in the lower or upper regions of the oval-shaped enclosure, particularly at e = - 0.3. The highest heat transfer rates were observed at β = 60 and 240.