Thermal analysis of nanofluid flow containing gyrotactic microorganisms in bioconvection and second-order slip with convective condition

Journal of Thermal Analysis and Calorimetry - Bioconvection in magneto-nanoliquid embedded with gyrotactic microorganisms across an elongated sheet with velocity slip of second order is addressed....     

Thermal and concentration convection in nanofluids for peristaltic flow of magneto couple stress fluid in a nonuniform channel

Journal of Thermal Analysis and Calorimetry - This article addresses the influence of double-diffusivity convection in nanofluids in relation to peristaltic flow of magneto couple stress fluid in a...     

Thermal convection and boiling in a porous medium

Experimental observations of boiling in a water-saturated porous medium are reported. The porous medium is contained in a vertical circular cylinder of diameter D and height H which is heated from below and cooled from above. Single-cell thermal convection occurs prior to the onset of boiling. With the onset of boiling, an isothermal two-phase zone forms above the bottom in regions of ascending convection. The size of the two-phase zone increases with increasing heat flux. At high heat fluxes the cellular convertion flow disappears; a horizontal water layer is then observed to overlie a two-phase layer. A vertical countercurrent flow of liquid and vapor dominates heat transfer in the two-phase layer. In the layered state, an oscillatory boiling mode can develop which is attributed to the periodic formation of a vapor layer at the heating surface.     

Computational modeling of porous medium inside a channel with homogeneous nanofluid

Journal of Thermal Analysis and Calorimetry - In the present study, the flow field and heat transfer have been simulated numerically inside a channel. The channel is under the constant heat flux....     

Simulation of thermal radiation in a micropolar fluid flow through a porous medium between channel walls

Journal of Thermal Analysis and Calorimetry - Among numerous methods which have been employed to reinforce the thermal efficiency in many systems, one is the thermal radiation which is a mode of...     

Pulsating flow in a channel filled with a porous medium under local thermal non-equilibrium condition: an exact solution

Journal of Thermal Analysis and Calorimetry - The present work investigates analytically the problem of forced convection heat transfer of a pulsating flow, in a channel filled with a porous medium...     

Synthesis and characterization of ZnS nanosized semiconductor particles within mesoporous solids

ZnS semiconductor quantum dots have been synthesized using a method involving melt exchange reaction inside the pores of MCM-41 and subsequent reaction with H(2)S. The ZnS quantum dots-MCM-41 composite, which has been studied with XRD, EDS, and BET techniques, is shown to have retained within the pores the formed quantum dots, with a size distribution exhibiting a maximum nanoparticle diameter of ca. 1.8 nm. The structure and the sorption properties of the ZnS/MCM-41 composite have been studied by means of X-ray diffraction, Fourier transform infrared spectroscopy, and surface area measurements. All experimental data reveal that all the final composite products, containing up to 9.3 wt % ZnS as verified by EDS analysis, keep the basic structural characteristics of MCM-41 materials, without significant reduction of their active surface areas. The quantum dot optical properties have been studied with UV-vis, photoluminescence, and photoluminescence excitation spectroscopies providing evidence for the low-dimensional character of the ZnS semiconductor particles.     

Scaling group analysis of bioconvective micropolar fluid flow and heat transfer in a porous medium

Journal of Thermal Analysis and Calorimetry - The current and potential applications of bioconvection renewed drive for theoretical research on synthesis and process control in biofuel cells and...     

Entropy analysis on the bioconvective peristaltic flow of gyrotactic microbes in Eyring-Powell nanofluid through an asymmetric channel

The educational value of nanofluids in several industrial and biological sectors, particularly in fluid movement systems known as peristalsis, has piqued researchers' interest in studying the peristaltic movement of nanofluids. Additionally, nanoparticles have crucial roles in many engineering and manufacturing processes, including those involving heat exchangers, cooling systems, boilers, MEMS, chemical engineering, laser diode arrays, and cool automotive engines. Various studies have been conducted on this subject. This is done by looking at how migratory gyrotactic microorganisms migrate through an artery that is anisotropically narrowing in a blood-based nanofluid that is non-Newtonian. To comprehend, the Powell-Eyring fluid model is used how the blood's rheology differs from that of a Newtonian fluid. Both Newtonian fluid characteristics and non-Newtonian traits can be seen in this fluid pattern. Equations for continuity, temperature, motile microbes, momentum, and concentration are used to create the mathematical formulation. The series solutions, which are produced using perturbation theory solutions are discussed using graphs for all dominant parameters. Discussion also includes the distribution of temperature, velocity, and swimming microorganisms. Additionally, the effects of wall shear stress, the Nusselt and Sherwood numbers, as well as the phenomena of trapping, are all examined in detail and shown in the graphs. Entropy generation analyses have also been undertaken. The investigation also reveals a crucial behaviour in the use of the heart-lung engine for extracorporeal blood circulation in medicine that may have an impact on the damage of red blood cells as a result of the large fluctuation in wall shear stress. When liquids are transported using arthro pumps and roller pumps in living organs, the results are likewise of significant use. The results are very helpful for executing particle movements in cardiac surgery and may be applicable to the fluid peristaltic pump used in haemodialysis.     

Effect of wall slip on the shear flow of a polymer in a channel with a wavy bottom

The effect of stick and wall slip boundary conditions on the specific features of the shear flow of viscous polymers in a confined two-dimensional channel with a wavy bottom is studied. The distribution of flow-rate disturbances across the transverse cross section of the channel is calculated by the numerical simulation of the Navier-Stokes equation for an incompressible fluid at arbitrary amplitudes and an arbitrary wave number of the wall. The wall slip is modeled by the introduction of a thin layer of a low-viscosity fluid at the bottom face. Slippage leads to a marked enhancement of flow rate disturbances including inertial advection. The results agree with the known analytical solutions for the low-amplitude wall wave.     

Impact of heat and mass transfer on the peristaltic mechanism of Jeffery fluid in a non-uniform porous channel with variable viscosity and thermal conductivity

Journal of Thermal Analysis and Calorimetry - The present examination emphasizes the effects of heat and mass transfer on the peristaltic flow of Jeffery fluid through a non-uniform channel with...     

The adsorption interaction of a rutin-biopolymer complex with nanosized silica particles

The influence of complex formation with biopolymers on the optical and acid properties of natural flavonoid rutin was studied. The adsorption interaction of biologically active flavonoids from officinal plants with the surface of nanosized silica particles was found to depend on the chemical nature of the biopolymer and adsorbate and solution properties.     

Stability of the jet flow of charged particles in a gaseous medium

The dynamics of the unidimensional straight-line motion of charged liquid droplets has been considered. Stability criterion has been derived for the jet motion of liquid droplets in a space bounded by two electrodes. The motion of an ensemble of charged droplets in a constant electric field and in a nonuniform field between a needle-like electrode and a plane has been calculated by the molecular dynamics method. Experimental data have been presented on the motion of micron and submicron charged particles formed by the electrostatic spraying of different liquids. The experimental data have been compared with the theoretical calculations and numerical simulation results.     

Dynamics of a bilayer membrane with membrane-solvent partial slip boundary conditions

We discuss the dynamics of a bilayer membrane with partial slip boundary conditions between the monolayers and the bulk fluid. Using Onsager’s variational principle to account for the associated dissipations, we derive the coupled dynamic equations for the membrane height and the excess lipid density. The newly introduced friction coe?cients appear in the renormalized fluid viscosities. For ordinary lipid bilayer membranes, we find that it is generally justified to ignore the e?ects of permeation and parallel slip at the membrane surface.     

Synthesis of nanosized BaSO4 particles with a membrane reactor: effects of operating parameters on particles

Nanosized BaSO₄ particles were synthesized successfully by a membrane reactor, in which Na₂SO₄ solution permeated through the micropores of ultrafiltration (UF) membrane gradually into BaCl₂ solution to control the saturation ratio, nucleation and growth rates. The effects of membrane molecular weight cut-off (MWCO), temperature, transmembrane pressure and reactant concentration on the particles morphology were investigated. The results reveal that the products tend from nanoparticles towards aggregates with the increase in membrane MWCO and reactant concentrations. Higher temperature favors the synthesis of regular particles. Transmembrane pressure does not show significant influences on the particles under the experimental conditions.     

Local non-similar solutions for free convective flow with uniform lateral mass flux in a porous medium

The problem of free convection along a vertical plane source or sink with uniform lateral mass flux in a porous medium is solved by the local non-similarity approximation. Solutions are carried out to the third level of truncation. Results for heat transfer characteristics as obtained from the third level of truncation are found in excellent agreement with a previous investigation using the finite difference method for a wide range of the mass flux parameter.     

Synthesis of nanosized BaSO4 and CaCO3 particles with a membrane reactor: effects of additives on particles

Nanosized BaSO(4) particles, about 15 nm in size, were synthesized successfully by a membrane reactor at the aids of additives, in which Na(2)SO(4) solutions were added into BaCl(2) solutions gradually through the micropores of ultrafiltration membranes to control the saturation ratio, subsequently the nucleation and growth rates. The effects of additives species, additives concentrations, and membranes molecular weight cut-off (MWCO) on the particle morphology, along with the formation processes of particles, were investigated. CaCO(3) nanoparticles of 30-60 nm in size were also prepared by the reactor. The results revealed that the addition of methyl alcohol, ethanol etc. favor the synthesis of nanoparticles with small size. The particles size decreases with the increase in ethanol concentrations. With the increase in membrane MWCO, the products tend from nanoparticles towards aggregates.     

Thermal analysis for heat transfer enhancement in electroosmosis-modulated peristaltic transport of Sutterby nanofluids in a microfluidic vessel

Viscosity plays a crucial role in the flow and heat transfer process of nanofluids. To effectively calculate and predict the changing characteristics of nanofluids viscosity, this study presents a theoretical model combining the static interface layer and dynamic Brownian motion mechanisms of spherical nanoparticles for water-based Newtonian nanofluids. The model describes the reasonable dependences of nanofluids viscosity on physical properties of nanoparticles (density, volume fraction, size) and base fluid (temperature, viscosity, density). Taking four kinds of typical water-based Newtonian nanofluids containing spherical oxide nanoparticles (Al₂O₃, CuO, SiO₂ and TiO₂) as examples, the prediction performance of different viscosity models is analyzed in detail. From the comparison studies, it is demonstrated that the new viscosity model developed in this paper can exhibit better prediction performance than many well-known theoretical models and empirical correlations. Not only do the predicted results of model agree well with the experimental data from various studies, but also the effects of different factors are reflected effectively.

     

Entropy generation analysis for nanofluid flow inside a duct equipped with porous baffles

Journal of Thermal Analysis and Calorimetry - In this research, a numerical simulation is performed to investigate thermal and viscous irreversibilities for Al2O3–water nanofluid inside a...