Passive control of nanoparticles in stagnation point flow of Oldroyd-B nanofluid with aspect of magnetic dipole

The present research focuses on nanoparticle suspensions and flow properties in the context of their applications. The application of these materials in biological rheological models has piqued the attention of many researchers. Magneto nanoparticles have an important function in controlling the viscoelastic physiognomies of ferrofluid flows. Having such substantial interest in the flow of ferroliquids our vision is to discuss the stagnation point flow of ferromagnetic Oldroyd-B nanofluid through a stretching sheet. The Buongiorno nanofluid model with Brownian motion and thermophoretic properties is examined. A chemical reaction effect and porous medium is also taken into account. Moreover, the modelled equations are changed to ordinary differential equations (ODEs) using suitable similarity transformations. Which are then solved using classical Runge-Kutta (RK) process with shooting technique. The solutions for the flow, thermal, concentration, skin friction, rate of heat and mass transfer features are attained numerically and presented graphically. The significant results of the current study are that, the growing values of ferromagnetic interaction parameter and porosity parameter declines the velocity profile. The rising values of chemical reaction rate parameter and Brownian motion parameter declines the mass transfer but inverse behaviour is seen for augmented values of thermophoresis parameter.

Analysis of Maxwell bioconvective nanofluids with surface suction and slip conditions in the presence of solar radiations

Several researchers have studied nanofluids over the past several decades and tried to identify potential agents that are added to nanofluids (nanoparticle suspensions) with tremendous thermal conductivity. In such suspensions, the Brownian motion of nanoparticles is the only means expected to be associated with the improved thermal conductivity of nanofluids, and the sections that may add to this are the subject of main conversation and discussion. In the current evaluation, the effect of Brownian motion has been investigated by injecting nanoparticles into the base fluid, and the existing fundamental information is available at creation. Propagation results show that this mixing effect can significantly increase the thermal conductivity of nanofluids. One of the interesting features of this model is that the temperature can be increased by the energy of sunlight, which is required for some industrial processes. The stretching property of the sheet is more conducive to the temperature rise. This model contains features that have not been previously studied, which is driving demand for this model in a variety of industries, now and in future generations.

The Protection of Building Materials of Historical Monuments with Nanoparticle Suspensions

Marble and limestone have been extensively used as building materials in historical monuments. Environmental, physical, chemical and biological factors contribute to stone deterioration. The rehabilitation of stone damage and the delay of further deterioration is of utmost importance. Inorganic nanoparticles having chemical and crystallographic affinity with building materials is very important for the formation of protective coatings or overlayers. In the present work, we have tested the possibility of treating calcitic materials with suspensions of amorphous calcium carbonate (am-CaCO3, ACC) and amorphous silica (AmSiO2). Pentelic marble (PM) was selected as the test material to validate the efficiency of the nanoparticle suspension treatment towards dissolution in undersaturated solutions and slightly acidic pH (6.50). Suspensions of ACC and AnSiO2 nanoparticles were prepared by spontaneous precipitation from supersaturated solutions and by tetraethyl orthosilicate (TEOS) hydrolysis, respectively. The suspensions were quite stable (nine days for ACC and months for AmSiO2). ACC and Am SiO2 particles were deposited on the surface of powdered PM. The rates of dissolution of PM were measured in solutions undersaturated with respect to calcite at a constant pH of 6.50. For specimens treated with ACC and AmSiO2 suspensions, the measured dissolution rates were significantly lower. The extent of the rate of dissolution reduction was higher for AmSiO2 particles on PM. Moreover, application of the nanoparticles on the substrate during their precipitation was most efficient method.

The damping of terahertz acoustic modes in aqueous nanoparticle suspensions

In this work, we investigate the possibility of controlling the acoustic damping in a liquid when nanoparticles are suspended in it. To shed light on this topic, we performed Inelastic X-Ray Scattering (IXS) measurements of the terahertz collective dynamics of aqueous suspensions of nanospheres of various materials, size, and relative concentration, either charged or neutral. A Bayesian analysis of measured spectra indicates that the damping of the two acoustic modes of water increases upon nanoparticle immersion. This effect seems particularly pronounced for the longitudinal acoustic mode, which, whenever visible at all, rapidly damps off when increasing the exchanged wavevector. Results also indicate that the observed effect strongly depends on the material the immersed nanoparticles are made of.

Particle Deposition in Drying Porous Media

The drying of porous media is a ubiquitous phenomenon in soils and building materials. The fluid often contains suspended particles. Particle deposition may modify significantly the final material, as it could be pollutants or clogging the pores, decreasing the porosity, such as in salt, in which particles and drying kinetics are coupled. Here, we used SEM and X-ray microtomography to investigate the dried porous media initially saturated by nanoparticle suspensions. As the suspensions were dried, nanoparticles formed a solid deposit, which added to the initial solid matrix and decreased the porosity. We demonstrate that since the drying occurred through the top surface, the deposit is not uniform as a function of depth. Indeed, the particles were advected by the liquid flow toward the evaporative surface; the deposit was significant over a depth that depended on the initial volume fraction, but the pore size was affected over a very narrow length. These findings were interpreted in the frame of a physical model. This study may help to design better porous media and take into account particle influence in drying processes.

Crustal-scale transport of nanoparticle emulsion forms ore deposits

A 10- to 10 000-fold enrichment is required to form economic metal deposits. Such enrichment is achieved through the accumulation of metals transported in hydrothermal fluids from their source to the deposit. The contribution of gold nanoparticle suspensions in fluids is required to form bonanza gold grades. However, as the source of gold is spatially disconnected from the deposit location, it is not known how the transport of gold nanoparticles is achieved. Here we show that metal nanoparticles (Au, AgO, AuAg Cu) are stabilised by colloidal silica in nanoparticle emulsion and transported with the aid of low-density carbonic phases. We document systematic occurrence of metals nanoparticle in five deposits that show a previously unrecognized association with amorphous silica and carbon. Our results demonstrate that stabilisation of metal nanoparticles may be achieved over kilometres through the Earth’s upper crust and offers a step change in our understanding of metalliferous deposit formation.