Durability performance of Green Concrete Incorporating Various Wastes: A Review

The present manuscript stands for the review on the topic of durability attribute of concretes developed by means of green conception with incorporation of a variety of solid industrial waste slag from Ground Granulated Blast Furnace, silica fume, rice husk ash, pulverised fly ash, glass powder waste as well as materials that have undergone recycling in order to know its degree of sustainability. It is highly sought-after to transform these types of waste into a precious adding up materials in place of Ordinary Portland Cement (OPC) in building-up of Green concrete with affordable cost and more essential with a little carbon footprint. How far these Green concept concretes have succeeded in context to its durability characteristic is the principal focus of this review study. There prevails an enormous demand for cost-effective construction materials for offering enough residences and infrastructure networks to get rid of the burgeoning population on the planet earth. The centre of attention is to make researcher, engineer and infrastructure related peoples, as well as construction industry au courant of absorbing the, dissipate materials and their promotion as an acceptable, sustainable and cost-effective building materials. The apposite standards of durability and still excellent researches on the sustainability of this novel Green concept concrete will encourage for espousal of gargantuan construction and infrastructures projects globally. Looking to the above facts, it can be predicted that the said Green technology bestows the impression to have dazzling potential and its approval in construction industries which establishes it as the most promising future edifice material

Mean turbulence statistics in boundary layers over high-porosity foams

This paper reports turbulent boundary layer measurements made over open-cell reticulated foams with varying pore size and thickness, but constant porosity ($\epsilon \approx 0.97$). The foams were flush-mounted into a cutout on a flat plate. A Laser Doppler Velocimeter (LDV) was used to measure mean streamwise velocity and turbulence intensity immediately upstream of the porous section, and at multiple measurement stations along the porous substrate. The friction Reynolds number upstream of the porous section was $Re_\tau \approx 1690$. For all but the thickest foam tested, the internal boundary layer was fully developed by $<10 \delta$ downstream from the porous transition, where $\delta$ is the boundary layer thickness. Fully developed mean velocity profiles showed the presence of a substantial slip velocity at the porous interface ($>30\%$ of the free stream velocity) and a mean velocity deficit relative to the canonical smooth-wall profile further from the wall. While the magnitude of the mean velocity deficit increased with average pore size, the slip velocity remained approximately constant. Fits to the mean velocity profile suggest that the logarithmic region is shifted relative to a smooth wall, and that this shift increases with pore size until it becomes comparable to substrate thickness $h$. For all foams, the turbulence intensity was found to be elevated further into the boundary layer to $y/ \delta \approx 0.2$. An outer peak in intensity was also evident for the largest pore sizes. Velocity spectra indicate that this outer peak is associated with large-scale structures resembling Kelvin-Helmholtz vortices that have streamwise length scale $2\delta-4\delta$. Skewness profiles suggest that these large-scale structures may have an amplitude-modulating effect on the interfacial turbulence

On the design of optimal compliant walls for turbulence control

This paper employs the theoretical framework developed by Luhar et al. (J. Fluid Mech., 768, 415-441) to consider the design of compliant walls for turbulent skin friction reduction. Specifically, the effects of simple spring-damper walls are contrasted with the effects of more complex walls incorporating tension, stiffness and anisotropy. In addition, varying mass ratios are tested to provide insight into differences between aerodynamic and hydrodynamic applications. Despite the differing physical responses, all the walls tested exhibit some important common features. First, the effect of the walls (positive or negative) is greatest at conditions close to resonance, with sharp transitions in performance across the resonant frequency or phase speed. Second, compliant walls are predicted to have a more pronounced effect on slower-moving structures because such structures generally have larger wall-pressure signatures. Third, two-dimensional (spanwise constant) structures are particularly susceptible to further amplification. These features are consistent with many previous experiments and simulations, suggesting that mitigating the rise of such two-dimensional structures is essential to designing performance-improving walls. For instance, it is shown that further amplification of such large-scale two-dimensional structures explains why the optimal anisotropic walls identified by Fukagata et al. via DNS (J. Turb., 9, 1-17) only led to drag reduction in very small domains. The above observations are used to develop design and methodology guidelines for future research on compliant walls

Durability performance of Green Concrete Incorporating Various Wastes: A Review

The present manuscript stands for the review on the topic of durability attribute of concretes developed by means of green conception with incorporation of a variety of solid industrial waste slag from Ground Granulated Blast Furnace, silica fume, rice husk ash, pulverised fly ash, glass powder waste as well as materials that have undergone recycling in order to know its degree of sustainability. It is highly sought-after to transform these types of waste into a precious adding up materials in place of Ordinary Portland Cement (OPC) in building-up of Green concrete with affordable cost and more essential with a little carbon footprint. How far these Green concept concretes have succeeded in context to its durability characteristic is the principal focus of this review study. There prevails an enormous demand for cost-effective construction materials for offering enough residences and infrastructure networks to get rid of the burgeoning population on the planet earth. The centre of attention is to make researcher, engineer and infrastructure related peoples, as well as construction industry au courant of absorbing the, dissipate materials and their promotion as an acceptable, sustainable and cost-effective building materials. The apposite standards of durability and still excellent researches on the sustainability of this novel Green concept concrete will encourage for espousal of gargantuan construction and infrastructures projects globally. Looking to the above facts, it can be predicted that the said Green technology bestows the impression to have dazzling potential and its approval in construction industries which establishes it as the most promising future edifice material

Phase relationships between velocity, wall pressure, and wall shear stress in a forced turbulent boundary layer

A large scale spatio-temporally periodic disturbance was excited in a turbulent boundary layer via a wall-actuated dynamic roughness. Streamwise velocity, wall pressure, and direct wall shear stress measurements were made with a hot wire, pressure microphone, and a micro-scale differential capacitive sensor, respectively. Phase-averaged fields for the three quantities were calculated and analyzed. A phase calibration between the various sensors was performed with an acoustic plane wave tube over a range of operating conditions to validate a direct phase comparison between the respective quantities. Results suggest encouraging agreement between the phase of the wall shear stress and velocity near the wall; however, more refined velocity measurements are needed to make quantitative comparisons to the wall pressure. Overall, this work highlights the potential for wall-based control with applications towards reducing turbulent drag

Plant patch hydrodynamics in streams : Mean flow, turbulence, and drag forces

Peer reviewedPreprin

Trends in the socioeconomic patterning of overweight and obesity and predictions of the future prevalence of diabetes in India

The prevalence of overweight and obesity in India has increased substantially in recent decades, and Indians are particularly predisposed to diabetes. Despite this, recent trends in the socioeconomic patterning of overweight and obesity are currently unknown, and reliable future forecasts of overweight, obesity and diabetes to assist policy makers are over-simplistic. The main aims of this thesis were to: (I) examine recent trends in the socioeconomic patterning of overweight and obesity in India, (II) estimate the future prevalence of overweight, obesity and diabetes to 2040, and (III) estimate residual lifetime risk of diabetes. The first objective was addressed using multilevel regression analysis, and the second and third by building dynamic simulation models. Input data were extracted from national surveys, census demographic data and community level cohort studies. The research identified considerably greater increases in overweight and obesity prevalence between 1998 and 2016 in poorer, compared to richer, socioeconomic groups particularly in urban areas, the most economically developed states, and among women. Among 20-69-year-old Indians, overweight and obesity prevalence is forecast to reach 30% and 10% among men, and 27% and 14% among women by 2040. The resultant prevalence of diabetes among urban men and women, respectively, in 2040 is expected to reach 27% and 25%. The lifetime probability of developing diabetes at 20 years among urban men and women is 69% and 75%, respectively, however is considerably higher among the obese population. This thesis marks the most recent attempt to identify the trends in the socioeconomic patterning of excess weight in India, the most thorough attempt to forecast future overweight, obesity and diabetes, and the first to examine the lifetime risk of diabetes. These findings are intended to guide future policy and monitor progress goals related to both excess weight and diabetes