Search Results (8)

This study deals with the analysis of the heat and velocity profile of the fractional-order Oldroyd-B bio-nanofluid within a bounded channel. The study has a wide range of scope in modern fields of basic science such as medicine, the food industry, electrical appliances, nuclear as well as industrial cooling systems, reducing pollutants, fluids used in the brake systems of vehicles, etc. Oldroyd-B fluid is taken as a bio-nanofluid composed of base fluid (blood) and copper as nanoparticles. Using the fractional-order Oldroyd-B parameter, the governing equation is generalized from an integer to a non-integer form. A strong approach, i.e., a finite difference scheme, is applied to discretize the model, because the fractional approach can well address the physical phenomena and memory effect of the flow regime. Therefore, a Caputo fractional differentiation operator is used for the purpose. The transformations for the channel flow are utilized to transfigure the fractional-order partial differential equations (PDEs) into non-dimension PDEs. The graphical outcomes for non-integer ordered Oldroyd-B bio-nanofluid dynamics and temperature profiles are navigated using the numerical technique. These results are obtained under some very important physical conditions applied as a magnetic field effect, variable thermal conductivity, permeable medium, and heat source/sink. The results show that the addition of (copper) nanoparticles to (blood) base fluids enhances the thermal conductivity. For a comparative study, the obtained results are compared with the built-in results using the mathematical software MAPLE 2016. Full article

Hyperthermia, an alternative medical approach aiming at locally increasing the temperature of a tumor, can cause the “death” of cancer cells or the sensitization of them to chemotherapeutic drugs and radiation. In contrast with the conventional treatments, hyperthermia provokes no injury to normal tissues. In particular, magnetic hyperthermia can utilize iron oxide nanoparticles, which can be administered intravenously to heat tumors under an alternating magnetic field. Currently, there is no theoretical model in the relative literature for the effective thermal conductivity of blood and magnetic nanoparticles. The scope of the present study is twofold: (a) development of a theoretical relationship, based on experimental findings and blood structure and (b) study of the laminar natural convection in a simplified rectangular porous enclosure, by using the asymptotic expansions method for deriving ordinary differential equations of the mass, momentum and energy balances, as a first approach of investigating heat transfer and providing theoretical guidelines. In short, the thermal conductivity of the resulting bio-nanofluid tends to increase by both increasing the concentration of the nanoparticles and the temperature. Furthermore, the heat transfer is enhanced for more intense internal heating (large Rayleigh numbers) and more permeable media (large Darcy numbers), while larger nanoparticle concentrations tend to suppress the flow. Full article

This study aimed to develop novel bio-nanofluids using Solanum torvum extracts in synergy with nanoparticles of different chemical nature as a proposal sustainable for enhanced oil recovery (EOR) applications. For this, saponin-rich extracts (SRE) were obtained from Solanum torvum fruit using ultrasound-assisted and Soxhlet extraction. The results revealed that Soxhlet is more efficient for obtaining SRE from Solanum torvum and that degreasing does not generate additional yields. SRE was characterized by Fourier transformed infrared spectrophotometry, thermogravimetric analysis, hydrophilic–lipophilic balance, and critical micelle concentration analyses. Bio-nanofluids based on SiO₂ (strong acid), ZrO₂ (acid), Al₂O₃ (neutral), and MgO (basic) nanoparticles and SRE were designed to evaluate the effect of the chemical nature of the nanoparticles on the SRE performance. The results show that 100 mg L⁻¹ MgO nanoparticles improved the interfacial tension up to 57% and the capillary number increased by two orders of magnitude using this bio-nanofluid. SRE solutions enhanced with MgO recovered about 21% more than the system in the absence of nanoparticles. The addition of MgO nanoparticles did not cause a loss of injectivity. This is the first study on the surface-active properties of Solanum torvum enhanced with nanomaterials as an environmentally friendly EOR process. Full article

The main objective of this study is to develop a novel green-nanofluid from Sapindus Saponaria for its application in enhanced oil recovery (EOR) processes. The bio-nanofluid is composed of a green active compound (AGC), bio-ethanol, and commercial surfactant (SB) at a low concentration. The AGC was obtained from soapberry “Sapindus Saponaria” using the alcoholic extraction method and characterized by Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and critical micellar concentration (CMC) to verify the content of saponins as active agents with surface-active behavior. Three types of silica-based nanoparticles were used and characterized by FTIR, TGA, and dynamic light scattering (DLS) analysis. Two commercial nanoparticles (SiO₂-C₁ and SiO₂-C₂) were evaluated, and a third one (SiO₂-RH) was synthesized from rice husks as an ecological nanomaterial alternative. The performance of the adjusted systems was evaluated by capillary number (effective interfacial tension (${\sigma }_e$), wettability and viscosity) and finally with coreflooding tests under reservoir conditions. The FTIR results confirm the presence of saponins in the AGC. In addition, according to the TGA, the AGC is stable under the reservoir temperature of interest. Regarding nanoparticles, siloxane and silanol groups were observed in all samples. For SiO₂-C₁ and SiO₂-C₂ samples, the weight loss was lower than 5% for temperatures up to 700 °C. Meanwhile, SiO₂-RH had a weight loss of 12% at 800 °C, and 8% at reservoir temperature. Results show a decrease in the interfacial tension (IFT) of up to 83% of the tuned system with only 100 mg·L⁻¹ of rice husk nanoparticles compared to the system without nanoparticles, reaching values of 1.60 × 10⁻¹ mN·m⁻¹. In the coreflooding test, increases of up to 13% of additional crude oil were obtained using the best bio-nanofluid. This work presents an excellent opportunity to include green alternatives to improve conventional techniques with added value during the injection of chemicals in chemical-enhanced oil recovery (CEOR) processes. Full article

Rheology of MHD bioconvective nanofluid containing motile microorganisms is inspected numerically in order to analyze heat and mass transfer characteristics. Bioconvection is implemented by combined effects of magnetic field and buoyancy force. Gyrotactic microorganisms enhance the heat and transfer as well as perk up the nanomaterials’ stability. Variable transport properties along with assisting and opposing flow situations are taken into account. The significant influences of thermophoresis and Brownian motion have also been taken by employing Buongiorno’s model of nanofluid. Lie group analysis approach is utilized in order to compute the absolute invariants for the system of differential equations, which are solved numerically using Adams-Bashforth technique. Validity of results is confirmed by performing error analysis. Graphical and numerical illustrations are prepared in order to get the physical insight of the considered analysis. It is observed that for controlling parameters corresponding to variable transport properties c₂, c₄, c₆, and c₈, the velocity, temperature, concentration, and bioconvection density distributions accelerates, respectively. While heat and mass transfer rates increases for convection parameter and bioconvection Rayleigh number, respectively. Full article

Three different fractional models of Oldroyd-B fluid are considered in this work. Blood is taken as a special example of Oldroyd-B fluid (base fluid) with the suspension of gold nanoparticles, making the solution a biomagnetic non-Newtonian nanofluid. Based on three different definitions of fractional operators, three different models of the resulting nanofluid are developed. These three operators are based on the definitions of Caputo (C), Caputo–Fabrizio (CF), and Atnagana–Baleanu in the Caputo sense (ABC). Nanofluid is taken over an upright plate with ramped wall heating and time-dependent fluid velocity at the sidewall. The effects of magnetohydrodynamic (MHD) and porous medium are also considered. Triple fractional analysis is performed to solve the resulting three models, based on three different fractional operators. The Laplace transform is applied to each problem separately, and Zakian’s numerical algorithm is used for the Laplace inversion. The solutions are presented in various graphs with physical arguments. Results are computed and shown in various plots. The empirical results indicate that, for ramped temperature, the temperature field is highest for the ABC derivative, followed by the CF and Caputo fractional derivatives. In contrast, for isothermal temperature, the temperature field of C-derivative is higher than the CF and ABC derivatives, respectively. It was noticed that the velocity field for the ABC derivative is higher than the CF and Caputo fractional derivatives for ramped velocity. However, the velocity field for the Caputo fractional derivative is lower than the ABC and CF for isothermal velocity. Full article

The study of laminar flow of heat and mass transfer over a moving surface in bionanofluid is of considerable interest because of its importance for industrial and technological processes such as fabrication of bio-nano materials and thermally enhanced media for bio-inspired fuel cells. Hence, the present work deals with the unsteady bionanofluid flow, heat and mass transfer past an impermeable stretching/shrinking sheet. The appropriate similarity solutions transform the boundary layer equations with three independent variables to a system of ordinary differential equations with one independent variable. The finite difference coupled with the Richardson extrapolation technique in the Maple software solves the reduced system, numerically. The rate of heat transfer is found to be higher when the flow is decelerated past a stretching sheet. It is understood that the state of shrinking sheet limits the rate of heat transfer and the density of the motile microorganisms in the stagnation region. Full article

This paper studies the combined effects of viscous dissipation, first and second-order slip and variable transport properties on phase-change hydromagnetic bio-nanofluid convection flow from a stretching sheet. Nanoscale materials possess a much larger surface to volume ratio than bulk materials, significantly modifying their thermodynamic and thermal properties and substantially lowering the melting point. Gyrotactic non-magnetic micro-organisms are present in the nanofluid. The transport properties are assumed to be dependent on concentration and temperature. Via appropriate similarity variables, the governing equation with boundary conditions are converted to nonlinear ordinary differential equations and are solved using the BVP4C subroutine in the symbolic software MATLAB. The non-dimensional boundary value features a melting (phase change) parameter, temperature-dependent thermal conductive parameter, first as well as second-order slip parameters, mass diffusivity parameter, Schmidt number, microorganism diffusivity parameter, bioconvection Schmidt number, magnetic body force parameter, Brownian motion and thermophoresis parameters. Extensive computations are visualized for the influence of these parameters. The present simulation is of relevance in the fabrication of bio-nanomaterials for bio-inspired fuel cells. Full article