Higher Order Chemical Reaction and Radiation Effects On MHD Flow of a Maxwell Nanofluid with Cattaneo-Christov Heat Flux Model Over a Stretching Sheet in a Porous Medium

In this paper, we investigated the heat and mass transfer analysis of an MHD convection flow of Maxwell nanofluid with Cattaneo-Christov heat flux model along with a porous stretching sheet. The effects of thermal radiation, viscous dissipation, suction/injection and higher-order chemical reaction are taken into consideration. By using similarity transformations the governing equations of the study are reduced into a system of ordinary differential equations and solved numerically by using the BVP5C MATLAB package. The effects of dimensionless parameters on the present study are deliberated with the aid of graphs and tables. It is found that an increase in thermal Grashof number, thermal radiation and thermal relaxation time parameter drops the temperature field. The heat transfer rate is declined with enhancing heat source, Brownian motion and thermophoresis parameters. Also, observed that the concentration field reduces with the rising value of chemical reaction. The numerically computed values of Nusselt number and Sherwood number are validated with existing literature and found a good agreement.

Heat Transfer of Nanomaterial over an Infinite Disk with Marangoni Convection: A Modified Fourier’s Heat Flux Model for Solar Thermal System Applications

The demand for energy due to the population boom, together with the harmful consequences of fossil fuels, makes it essential to explore renewable thermal energy. Solar Thermal Systems (STS’s) are important alternatives to conventional fossil fuels, owing to their ability to convert solar thermal energy into heat and electricity. However, improving the efficiency of solar thermal systems is the biggest challenge for researchers. Nanomaterial is an effective technique for improving the efficiency of STS’s by using nanomaterials as working fluids. Therefore, the present theoretical study aims to explore the thermal energy characteristics of the flow of nanomaterials generated by the surface gradient (Marangoni convection) on a disk surface subjected to two different thermal energy modulations. Instead of the conventional Fourier heat flux law to examine heat transfer characteristics, the Cattaneo–Christov heat flux (Fourier’s heat flux model) law is accounted for. The inhomogeneous nanomaterial model is used in mathematical modeling. The exponential form of thermal energy modulations is incorporated. The finite-difference technique along with Richardson extrapolation is used to treat the governing problem. The effects of the key parameters on flow distributions were analyzed in detail. Numerical calculations were performed to obtain correlations giving the reduced Nusselt number and the reduced Sherwood number in terms of relevant key parameters. The heat transfer rate of solar collectors increases due to the Marangoni convection. The thermophoresis phenomenon and chaotic movement of nanoparticles in a working fluid of solar collectors enhance the temperature distribution of the system. Furthermore, the thermal field is enhanced due to the thermal energy modulations. The results find applications in solar thermal exchanger manufacturing processes.

Component-Based Model for Building Material Stock and Waste-Flow Characterization: A Case in the Île-de-France Region

Building demolition is one of the main sources of waste generation in urban areas and is a growing problem for cities due to the generated environmental impacts. To promote high levels of circular economy, it is necessary to better understand the waste-flow composition; nevertheless, material flow studies typically focus on low levels of detail. This article presents a model based on a bottom-up macro-component approach, which allows the multiscale characterization of construction materials and the estimation of demolition waste flows, a model that we call the BTP-flux model. Data mining, analytical techniques, and geographic information system (GIS) tools were used to assess different datasets available at the national level and develop a common database for French buildings: BDNB. Generic information for buildings in the BDNB is then enriched by coupling every building with a catalog of macro-components (TyPy), thus allowing the building’s physical description. Subsequently, stock and demolition flows are calculated by aggregation and classified into 32 waste categories. The BTP-flux model was applied in Île-de-France in a sample of 101,320 buildings for residential and non-residential uses, representative of the assessed population (1,968,242 buildings). In the case of Île-de-France, the building stock and the total demolition flows were estimated at 1382 Mt and 4065 kt, respectively. For its inter-regional areas—departments—, stock and demolition waste can vary between 85 and 138 tons/cap and 0.263 and 0.486 tons/cap/year, respectively. The mean of the total demolition wastes was estimated at 0.33 tons/cap/year for the region. Results could encourage scientists, planners, and stakeholders to develop pathways towards a circular economy in the construction sector by implementing strategies for better management of waste recovery and reintegrating in economic circuits, while preserving a maximum of their added value.

The ice thickness distribution of a debris-covered glacier: Tasman Glacier, New Zealand

<p>The ice thickness distribution of mountain valley glaciers is an important physical constraint for modelling their flow. Ice thickness measurements are used to calculate the geometry and ultimately the driving stress of a glacier. This information is all required if realistic models are to forecast the response of glaciers to climate forcings. For New Zealand's Tasman Glacier, two factors complicate its response to climate: 1) A layer of insulative rocky debris covers the lower half of the glacier, retarding surface melt, and 2) the glacier has recently entered a period of iceberg calving into a proglacial lake, introducing complex mechanical processes. These complications, along with the uncertainty of the current bed topography of the Tasman Glacier, make future predictions of its retreat behaviour difficult. The bed of the Tasman Glacier has not been fully imaged but ice thickness measurements obtained through seismic and gravity surveys have provided constraints for parts of the glacier. This study applies a range of geophysical methods (gravity and refraction seismics) to measure and model the ice thickness distribution of the lower Tasman Glacier. We surveyed orthogonal to glacier flow to obtain 12 transects within the lower 5 km of the glacier. Two-dimensional and three-dimensional gravity models generally indicate a U-shaped valley with ice thicknesses of 92-722 m from the present day terminus to the most upstream transect respectively. These results were used as input data to a simple mass flux model to assess its performance in estimating ice thickness and volume for the Tasman Glacier. The mass-flux model estimated a volume of 14.96 km3 for the Tasman Glacier, but generally underestimated ice thickness with an RMSE of 148 m between the modelled and the gravity-derived ice thickness. This discrepancy could be reduced by constraining ice thickness for a larger area of the glacier and providing a more recent DEM to the mass flux model. Studies such as this highlight the importance of constraining ice thickness in order to improve glacio-dynamic models and global volume estimates.</p>

The ice thickness distribution of a debris-covered glacier: Tasman Glacier, New Zealand

<p>The ice thickness distribution of mountain valley glaciers is an important physical constraint for modelling their flow. Ice thickness measurements are used to calculate the geometry and ultimately the driving stress of a glacier. This information is all required if realistic models are to forecast the response of glaciers to climate forcings. For New Zealand's Tasman Glacier, two factors complicate its response to climate: 1) A layer of insulative rocky debris covers the lower half of the glacier, retarding surface melt, and 2) the glacier has recently entered a period of iceberg calving into a proglacial lake, introducing complex mechanical processes. These complications, along with the uncertainty of the current bed topography of the Tasman Glacier, make future predictions of its retreat behaviour difficult. The bed of the Tasman Glacier has not been fully imaged but ice thickness measurements obtained through seismic and gravity surveys have provided constraints for parts of the glacier. This study applies a range of geophysical methods (gravity and refraction seismics) to measure and model the ice thickness distribution of the lower Tasman Glacier. We surveyed orthogonal to glacier flow to obtain 12 transects within the lower 5 km of the glacier. Two-dimensional and three-dimensional gravity models generally indicate a U-shaped valley with ice thicknesses of 92-722 m from the present day terminus to the most upstream transect respectively. These results were used as input data to a simple mass flux model to assess its performance in estimating ice thickness and volume for the Tasman Glacier. The mass-flux model estimated a volume of 14.96 km3 for the Tasman Glacier, but generally underestimated ice thickness with an RMSE of 148 m between the modelled and the gravity-derived ice thickness. This discrepancy could be reduced by constraining ice thickness for a larger area of the glacier and providing a more recent DEM to the mass flux model. Studies such as this highlight the importance of constraining ice thickness in order to improve glacio-dynamic models and global volume estimates.</p>

Homotopy perturbation method solution of magneto-polymer nanofluid containing gyrotactic microorganisms over the permeable sheet with Cattaneo–Christov heat and mass flux model

Many non-Newtonian materials behave as a polymeric solution and this type of materials is used in various industrial and physical applications such as polymer extraction, manufacturing processes, various geophysical systems, and glass production. Especially the gyrotactic microorganisms have widely used for the production of biodiesel, hydrogen, an essential sustainable energy source and in water treatment plants. This study intends to examine the impacts of magnetic field, convective boundary state on bioconvection of a tangent hyperbolic nanofluid in the presence of gyrotactic microorganisms over a porous stretching surface with a Cattaneo–Christov heat and mass flux model. Appropriate self-similarity variables are implemented to transform the fluid transport equations into ordinary differential equations that have been resolved using the homotopy perturbation method. The influences of effective parameters on transport properties of the fluid are represented with graphs and tables. This model forecast the shear-thinning attitude significantly and exactly describes the flow of fluids. It is noted from the obtained results that the velocity profile declines with raising the Weissenberg number and buoyancy ratio parameter. It also observed that the temperature profile rises with a growth in the radiation and thermal relaxation parameters. The higher values of the stagnation parameter increase the rate of heat transfer while it is opposite nature in the mixed convection parameter. Microorganisms density uplifts with an increase in Peclet number, while it decreases for the microorganism concentration difference. Microorganisms density increases with an enlargement in bioconvection Schmidt number.