Convective Energy Research Articles

Influence of Aqueous‐Phase Chemistry on the Concentrations of PM2.5 and Hydrometers During the Development of Convective Clouds Over the Yellow Sea in July of 2017

AbstractMeteorological processes are investigated during the development of deep convective clouds over the Yellow Sea inside a quasi‐stationary rainy front in the East Asian region. WRF‐Chem simulations were conducted to assess the effects of aqueous‐phase chemistry on the concentrations of PM2.5 and hydrometers in deep convective clouds and the associated precipitation. A reduction in the south‐north air temperature gradient induced an inactive quasi‐stationary rainy front with nonlinear zonal clouds during the Changma period in the East Asian region in 2017, causing intensified surface heating due to solar radiation. A mesoscale cyclone was formed near the Shantung Peninsula inside the inactive quasi‐stationary rainy front, extending the eastward tongue of the troughs across the Yellow Sea. Deep convective clouds (CC16 on July 16, CC17 on July 17, and CC18 on July 18) formed in a severe mode on the east side of the mesoscale cyclone over the Yellow Sea at midnight as the warm type, as the warm and humid south‐southwesterly winds present at that time produced convection energy. PM2.5 from eastern China flowed into warm‐type CC16, CC17, and CC18 areas, producing more cloud droplets below 500 hPa via activation. In contrast, the release of additional condensation heat amplifies updrafts within convective clouds during efficient nighttime environmental cooling, thereby enhancing the production of cold‐type ice, reaching altitudes of up to 15 km. The WRF‐Chem PM2.5 outcomes indicate a significant increase in heavy rainfall, exceeding 10 mm hr−1, particularly in the context of the development of cold‐type convective clouds.

Analytical, Experimental and Computational Analysis of Heat Released from a Hot Mug of Tea Coupled with Convection, Conduction, and Radiation Thermal Energy Modes

Analytical, Experimental and Computational Analysis of Heat Released from a Hot Mug of Tea Coupled with Convection, Conduction, and Radiation Thermal Energy Modes

A hybrid discrete exterior calculus and finite difference method for anelastic convection in spherical shells

The present work develops, verifies, and benchmarks a hybrid discrete exterior calculus and finite difference (DEC-FD) method for density-stratified thermal convection in spherical shells. Discrete exterior calculus (DEC) is notable for its coordinate independence and structure preservation properties. The hybrid DEC-FD method for Boussinesq convection has been developed by Mantravadi et al. (2023). Motivated by astrophysics problems, we extend this method assuming anelastic convection, which retains density stratification; this has been widely used for decades to understand thermal convection in stars and giant planets. In the present work, the governing equations are splitted into surface and radial components and discrete anelastic equations are derived by replacing spherical surface operators with DEC and radial operators with FD operators. The novel feature of this work is the discretization of anelastic equations with the DEC-FD method and the assessment of a hybrid solver for density-stratified thermal convection in spherical shells. The discretized anelastic equations are verified using the method of manufactured solution (MMS). We performed a series of three-dimensional convection simulations in a spherical shell geometry and examined the effect of density ratio on convective flow structures and energy dynamics. The present observations are in agreement with the benchmark models.

Benign Prostatic Hyperplasia Surgery: A Snapshot of Trends, Costs, and Surgical Retreatment Rates in the USA

BackgroundAn increasing number of novel surgical treatments (NSTs) for benign prostatic hyperplasia (BPH) have been proposed over time to achieve similar functional outcomes to, but better perioperative and sexual outcomes than traditional procedures. ObjectiveTo assess the trends in the utilization and costs of BPH surgical procedures over the past decade, and to analyze the need for surgical retreatment after each procedure. Design, setting, and participantsA retrospective observational population-based analysis was conducted using the PearlDiver Mariner (PearlDiver Technologies, Colorado Springs, CO, USA) database, including all-payer nationally available claims records collected from 2011 to 2022. Outcome measurements and statistical analysisThe number and type of BPH surgical procedures per year, costs associated with each BPH surgical treatment, incidence of BPH surgical retreatment rate, and time to BPH surgical retreatment were assessed. Negative binomial regression and Cochran-Armitage test were used for the temporal trend analysis. A multivariable logistic regression analysis evaluated the predictors of BPH surgical retreatment. Results and limitationsIn the study period, 274 808 patients received surgical treatment for BPH. The most common procedure was transurethral resection of the prostate (TURP; 71.7%). The overall utilization of BPH surgical treatment increased over the study period. Traditional surgery remained most performed for the entire period (87.8%), but a statistically significantly rising trend of NSTs was recorded. The mean reimbursements paid per procedure was 1.43 times higher (p < 0.001) for NSTs than for traditional procedures. The surgical retreatment rate was 9.4%. The mean time to surgical retreatment was 25.3 mo, with 85.5% of cases re-treated within 5 yr. At the multivariable analysis, transurethral incision of the prostate, photoselective vaporization of the prostate, prostatic urethral lift, convective water vapor energy, and prostatic artery embolization had a significantly greater likelihood of surgical retreatment than TURP. Holmium/thulium laser enucleation of the prostate (HoLEP/ThuLEP), open simple prostatectomy (SP), and laparoscopic/robot-assisted SP were associated with a lower probability of resurgery than TURP, but a similar probability between these procedures. Retrospective design and a lack of relevant clinical data were the main limitations. ConclusionsOver the past decade, there has been a progressive increase in the adoption of NSTs. The rate of surgical retreatment appears <10%, with patients undergoing SP and HoLEP/ThuLEP experiencing a statistically significantly lower probability of surgical retreatment. Patient summaryWe investigated the trends, costs, and surgical retreatments of benign prostatic hyperplasia surgery. Transurethral resection of the prostate remains the most common procedure. Novel surgical treatments are associated with an upward trend, despite appearing more expensive overall. Retreatment is necessary in <10% of patients and generally within 5 yr.

2D unified atmosphere and wind simulations of O-type stars

Context. Massive and luminous O-type star (O star) atmospheres with winds have been studied primarily using one-dimensional (1D), spherically symmetric, and stationary models. However, observations and theory have suggested that O star atmospheres are highly structured, turbulent, and time-dependent. As such, when making comparisons to observations, present-day 1D modeling tools require the introduction of ad hoc quantities such as photospheric macro- and microturbulence, wind clumping, and other relevant properties. Aims. We present a series of multi-dimensional, time-dependent, radiation-hydrodynamical (RHD) simulations for O stars that encapsulate the deeper sub-surface envelope (down to T ~ 450 kK), as well as the supersonic line-driven wind outflow in one unified approach. Our overarching aim is to develop a framework that is free from the ad-hoc prescriptions that plague present-day 1D models. Here, we start with an analysis of a small set of such multi-dimensional simulations and then compare them to atmospheric structures predicted by their 1D counterparts. Methods. We performed time-dependent, two-dimensional (2D) simulations of O star atmospheres with winds using a flux-limiting RHD finite volume modelling technique. Opacities are computed using a hybrid approach combining tabulated Rosseland means with calculations (based on the Sobolev approximation) of the enhanced line opacities expected for supersonic flows. The initial conditions and comparison models were derived using similar procedures as those applied in standard 1D stationary model atmosphere with wind codes. Results. Structure starts appearing in our simulations just below the iron-opacity peak at ~200 kK. Local pockets of gas with radiative accelerations that exceed gravity then shoot up from these deep layers into the upper atmosphere, where they interact with the line-driven wind outflow initiated around or beyond the variable photosphere. This complex interplay creates large turbulent velocities in the photospheric layers of our simulations, on the order of ~30–100km s−1, with higher values for models with higher luminosity-to-mass ratios. This offers a generally good agreement with observations of large photospheric ‘macroturbulence’ in O stars. When compared to 1D models, the average structures in the 2D simulations display less envelope expansion and no sharp density-inversions, along with density and temperature profiles that are significantly less steep around the photosphere, and a strong anti-correlation between velocity and density in the supersonic wind. Although the wind initiation region is complex and highly variable in our simulations, our average mass-loss rates agree well with stationary wind models computed by means of full co-moving frame radiative transfer solutions. Conclusions. The different atmospheric structures found in 2D and 1D simulations are likely to affect the spectroscopic determination of fundamental stellar and wind parameters for O stars as well as the empirical derivation of their chemical abundance patterns. To qualitatively match the different density and temperature profiles seen in our multi-dimensional and 1D models, we need to add a modest amount of convective energy transport in the deep sub-surface layers and a large turbulent pressure around the photosphere to the 1D models.

Are longer and more intense heatwaves more prone to extreme precipitation?

Simultaneous/sequential occurrence of multiple extreme climate events has the tendency to inflict greater damage compared to isolated extreme climate events. The exploration of simultaneous or continuous extreme events holds profound implications for disaster risk prevention. Therefore, we identified the compound heatwaves and extreme precipitation events (CHP, extreme precipitation events following heatwaves) in China based on ERA5 data. Then, the individual extreme events and compound events were undertaken through event coincidence analysis. Furthermore, the atmospheric background of individual extreme events and compound extreme events was further investigated. The results show that the CHP events with an increasing trend mainly occurred in northern China and northeastern the Qinghai-Tibet Plateau (QTP). Notably, after the year 2000, the time interval of extreme precipitation in CHP events was significantly shortened. In July and August, the trigger coincidence rate of extreme precipitations by heatwaves occurred higher and extreme precipitation events following heatwaves accounted for 40%. Moreover, Extreme precipitation is more likely to occur after a longer duration and higher intensity heatwave in the QTP. Convective effective potential energy (CAPE) and relative humidity manifest a considerable increase during the heatwave duration, greatly augmenting the risk of extreme precipitation events. In addition, the frequency of CHP events is higher in northern and northeastern China during El Niño years. While it predominantly concentrates in the northeast region in La Niña years.

Major Role of Marine Heatwave and Anthropogenic Climate Change on a Giant Hail Event in Spain

AbstractA severe hailstorm that occurred in Spain on 30 August 2022, caused material and human damage, including one fatality due to giant hailstones up to 12 cm in diameter. By applying a pseudo‐global warming approach, here we evaluate how a simultaneous marine heatwave (and anthropogenic climate change) affected a unique environment conductive to such giant hailstones. The main results show that the supercell development was influenced by an unprecedented amount of convective available energy, with significant contributions from thermodynamic factors. Numerical simulations where the marine heatwave is not present show a notable reduction in the hail‐favorable environments, related mainly to modifications in thermodynamic environment. Our simulations also indicate that the environment in a preindustrial‐like climate would be less favorable for convective hazards and thus the hailstorm event would likely not have been as severe as the observed one, being possible to perform a novel attribution of such kind.

Convective scale and subadiabatic layers in simulations of rotating compressible convection

Context. Rotation is thought to influence the size of convective eddies and the efficiency of convective energy transport in the deep convection zones of stars. Rotationally constrained convection has been invoked to explain the lack of large-scale power in observations of solar flows. Aims. Our main aims are to quantify the effects of rotation on the scale of convective eddies and velocity as well as the depths of convective overshoot and subadiabatic Deardorff layers. Methods. We ran moderately turbulent three-dimensional hydrodynamic simulations of rotating convection in local Cartesian domains. The rotation rate and luminosity of the simulations were varied in order to probe the dependency of the results on Coriolis, Mach, and Richardson numbers measuring the influences of rotation, compressibility, and stiffness of the radiative layer. The results were compared with theoretical scaling results that assume a balance between Coriolis, inertial, and buoyancy (Archimedean) forces, also referred to as the CIA balance. Results. The horizontal scale of convective eddies decreases as rotation increases, and it ultimately reaches a rotationally constrained regime consistent with the CIA balance. Using a new measure of the rotational influence on the system, we found that even the deep parts of the solar convection zone are not in the rotationally constrained regime. The simulations captured the slowly and rapidly rotating scaling laws predicted by theory, and the Sun appears to be in between these two regimes. Both the overshooting depth and the extent of the Deardorff layer decrease as rotation becomes more rapid. For sufficiently rapid rotation, the Deardorff layer is absent due to the symmetrisation of upflows and downflows. However, for the most rapidly rotating cases, the overshooting increases again due to unrealistically large Richardson numbers that allow convective columns to penetrate deep into the radiative layer. Conclusions. Relating the simulations with the Sun suggests that the convective scale, even in the deep parts of the Sun, is only mildly affected by rotation and that some other mechanism is needed to explain the lack of strong large-scale flows in the Sun. Taking the current results at face value, the overshoot and Deardorff layers are estimated to span roughly 5% of the pressure scale height at the base of the convection zone in the Sun.

Double diffusive on powell eyring fluid flow by mixed convection from an exponential stretching surface with variable viscosity/thermal conductivity

This study delves into heat and mass transference in fluids with variable thermo-physical features, focusing on the Powell-Eyring fluid, a non-Newtonian substance with unique characteristics. Our aim is to understand the behaviour of this shear-thinning fluid when interacting with an exponentially stretchable surface, considering factors like mixed convection and thermal radiation. Our research endeavours to uncover novel findings in this intricate domain, with the primary objective of comprehending how this shear-thinning fluid behaves when it encounters an exponentially stretchable surface. To address the complexities, we employ the BVP4C technique in MATLAB, transforming governing equations into nonlinear partial differential equations (PDEs) based on mass, linear momentum, and energy conservation principles. The Homotopy method aids in navigating these equations, and numerical solutions are calculated using the powerful BVP4C technique for ordinary differential equations (odes). The research stands out for its comprehensive exploration of the interplay among diverse factors, including radiation, variable viscosity, mixed convection, and activation energy constraints. Findings are presented through tables and graphs, offering valuable insights into the intricate physical phenomena within this multifaceted field.

Kinetic plasma-sheath self-organization

The interaction between a plasma and a solid surface is studied in a (1D–1V) kinetic framework using a localized particle and convective energy source. Matching the quasineutral plasma region and sheath horizon is addressed in the fluid framework with a zero heat flux closure. It highlights non-polytropic nature of the physics of parallel transport. Shortfalls of this approach compared to a reference kinetic simulation highlight the importance of the heat flux as the measure of kinetic effects. Non-collisional closure and higher moment closure are used to determine the sound velocity. Within these frameworks, no gain in the fluid predictive capability is obtained. The kinetic constraint at the sheath horizon is discussed and modified to account for conditions that are actually met in simulations, namely quasineutrality with a small but finite charge density. Analyzing the distribution functions shows that collisional transfer is mandatory to achieve steady-state self-organization on the open field lines.

Radar, Lightning, and Synoptic Observations for a Thunderstorm on 7 January 2012 during the CHUVA-Vale Campaign

Thunderstorms can generate intense electrical activity, hail, and result in substantial economic and human losses. The development of very short-term forecasting tools (nowcasting) is essential to provide information to alert systems in order to mobilize most efficiently the population. However, the development of nowcasting tools depends on a better understanding of the physics and microphysics of clouds and lightning formation and evolution. In this context, the objectives of this study are: (a) to describe the environmental conditions that led to a genesis of a thunderstorm that produce hail on 7 January 2012, in the Metropolitan Area of São Paulo (MASP) during the CHUVA-Vale campaign, and (b) to evaluate the thunderstorm microphysical properties and vertical structure of electrical charge. Data from different sources were used: field campaign data, such as S-band radar, and 2- and 3-dimensional lightning networks, satellite data from the Geostationary Operational Environmental Satellite-13 (GOES-13), the Meteosat Second Generation (MSG), and reanalysis of the European Centre for Medium-Range Weather Forecasts Reanalysis v5 (ERA5). The thunderstorm developed in a region of low-pressure due to the presence of a near-surface inverted trough and moisture convergence, which favored convection. Convective Available Potential Energy (CAPE) of 1053.6 J kg−1 at the start of the thunderstorm indicated that strong convective energy was present. Microphysical variables such as Vertically Integrated Liquid water content (VIL) and Vertically Integrated Ice (VII) showed peaks of 140 and 130 kg m−2, respectively, before the hail reached the surface, followed by a decrease, indicating content removal from within the clouds to the ground surface. The thunderstorm charge structure evolved from a dipolar structure (with a negative center between 4 and 6 km and a positive center between 8 and 10 km) to a tripolar structure (negative center between 6 and 7.5 km) in the most intense phase. The first lightning peak (100 flashes in 5 min−1) before the hail showed that there had been a lightning jump. The maximum lightning occurred around 18:17 UTC, with approximately 350 flashes 5 min−1 with values higher than 4000 sources 500 m−1 in 5 min−1. Likewise, the vertical cross-sections indicated that the lightning occurred ahead of the thunderstorm’s displacement (maximum reflectivity), which could be useful in predicting these events.

A modified model to assess the thermal protective performance of fire-retardant clothing exposed to both flame and radiant source

The present work evaluates the thermal protective performance (TPP) of a multi-layered fire-resistant fabric system subjected to a high intensity risky thermal environment integrating both flame and radiant heat exposure by developing a modified model for the fabric as well as the skin. The present numerical analysis takes into consideration a multiple-layer flameproof gear (outer shell, moisture barrier, and thermal liner), an airgap separating fabric and skin, and a three-layer of skin (epidermis, dermis, and fat layer). The present model is formulated by considering a two-flux model for the radiative heat interaction in the porous fabric medium and a nonlinear bioheat transfer model for the multi-layered skin. The radiative part of the total incident energy from the flame and the radiant heater is considered to be absorbed, emitted, reflected, and transmitted through the porous fibrous layer. Here, a two-flux model is implemented to simulate the self-emission of hot gas trapped inside the porous fabrics. The thermal response in multi-layered skin is analysed using a non-linear bioheat transfer model considering a temperature dependent thermal conductivity of the living tissue. Purely radiant exposure markedly impairs turnout gear protection, while performance deteriorates more gradually with increased convective thermal energy. Greater fabric transmissivity negatively affects skin temperature distribution and TPP ratings more than equivalent reflection reduction. These study results aid in enhancing flame-resistant fabric thermal protection.

Journey to the cosmos: Navigating stellar evolution with differential equations

Differential equations are a fundamental and versatile mathematical tool that finds widespread application across diverse academic disciplines, from physics and biology to economics and engineering. The primary objectives of this report are to demonstrate the application of differential equations in stellar evolution, construct a mathematical model to demonstrate nuclear reactions in a star, and illustrate energy transport within a star. Triangulation was used to prepare this report, with literature studies being the primary method. This study includes several documents and field data analyzed using qualitative research. Through research and observations, two hypothetical case studies illustrate the indispensable application of differential equations in modeling energy transport and nuclear reactions within stars through which the value of luminosity was calculated in a particular star due to both radiative energy transport and convective energy transport while in another star, the helium abundance in the core was estimated to approach a value of 1.195*1077. These differential equations are not only limited to the growth of a lead but also have broader applications that are essential for understanding the chemical composition of the universe and its prolonged evolution. The report also underscores the enduring importance of differential equations in advancing our understanding of the cosmos and their vital role in space exploration and technological innovations.

Insight into the dynamics of heat and mass transfer in nanofluid flow with linear/nonlinear mixed convection, thermal radiation, and activation energy effects over the rotating disk

In this paper, we study linear and nonlinear mixed convection, activation energy, and heat radiation effects caused by nanoparticles. This study aims to improve the understanding of how nanofluids behave in the presence of rotating disks and develop more efficient and effective cooling technologies. The flow problem consisted of partial differential equations (PDE). It is challenging to calculate these equations as a result of these nonlinear PDEs. Consequently, we use appropriate similarities to transform them into ordinary differential equations (ODEs). The bvp4c Matlab built-in technique is then used to resolve these ODEs. The velocities, temperature, and concentration outcomes with the various factors are examined graphically. Additionally, tables are employed to analyze the skin friction and Nusselt number values. It is analyzed that increasing the linear and linear mixed convection parameters enhances the velocity profiles of nanofluid. Enhancements in heat are analyzed by increasing nonlinear thermal radiation and enhancement in concentration is examined by increasing activation energy. Furthermore, as the variables for thermophoresis and Brownian motion are increased, the Nusselt number falls. The heat transfer rate is 27.16% for Rd=0.6\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$Rd=0.6$$\\end{document} and 39.28% for Rd=1.4\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$Rd=1.4$$\\end{document}. Thus, the heat transfer rate is enhanced 12.12%. This study’s practical applications include improving the behavior of fluids and the transfer of heat in rotating frameworks, which may affect energy systems, heat exchangers, and cooling advances in technology.

Magneto-thermal convection and entropy production of hybrid nanofluid in an inclined chamber having a solid block

PurposeThis paper aims to examine the thermal transmission and entropy generation of hybrid nanofluid filled containers with solid body inside. The solid body is seen as being both isothermal and capable of producing heat. A time-dependent non-linear partial differential equation is used to represent the transfer of heat through a solid body. The current study’s objective is to investigate the key properties of nanoparticles, external forces and particular attention paid to the impact of hybrid nanoparticles on entropy formation. This investigation is useful for researchers studying in the area of cavity flows to know features of the flow structures and nature of hybrid nanofluid characteristics. In addition, a detailed entropy generation analysis has been performed to highlight possible regimes with minimal entropy generation rates. Hybrid nanofluid has been proven to have useful qualities, making it an attractive coolant for an electrical device. The findings would help scientists and engineers better understand how to analyse convective heat transmission and how to forecast better heat transfer rates in cutting-edge technological systems used in industries such as heat transportation, power generation, chemical production and passive cooling systems for electronic devices.Design/methodology/approachThermal transmission and entropy generation of hybrid nanofluid are analysed within the enclosure. The domain of interest is a square chamber of size L, including a square solid block. The solid body is considered to be isothermal and generating heat. The flow driven by temperature gradient in the cavity is two-dimensional. The governing equations, formulated in dimensionless primitive variables with corresponding initial and boundary conditions, are worked out by using the finite volume technique with the SIMPLE algorithm on a uniformly staggered mesh. QUICK and central difference schemes were used to handle convective and diffusive elements. In-house code is developed using FORTRAN programming to visualize the isotherms, streamlines, heatlines and entropy contours, which are handled by Tecplot software. The influence of nanoparticles volume fraction, heat generation factor, external magnetic forces and an irreversibility ratio on energy transport and flow patterns is examined.FindingsThe results show that the hybrid nanoparticles concentration augments the thermal transmission and the entropy production increases also while the augmentation of temperature difference results in a diminution of entropy production. Finally, magnetic force has the significant impact on heat transfer, isotherms, streamlines and entropy. It has been observed that the external magnetic force plays a good role in thermal regulations.Research limitations/implicationsHybrid nanofluid is a desirable coolant for an electrical device. Various nanoparticles and their combinations can be analysed. Ferro-copper hybrid nanofluid considered with the help of prevailing literature review. The research would benefit scientists and engineers by improving their comprehension of how to analyses convective heat transmission and forecast more accurate heat transfer rates in various fields.Practical implicationsDue to its helpful characteristics, ferrous-copper hybrid nanofluid is a desirable coolant for an electrical device. The research would benefit scientists and engineers by improving their comprehension of how to analyse convective heat transmission and forecast more accurate heat transfer rates in cutting-edge technological systems used in sectors like thermal transportation, cooling systems for electronic devices, etc.Social implicationsEntropy generation is used for an evaluation of the system’s performance, which is an indicator of optimal design. Hence, in recent times, it does a good engineering sense to draw attention to irreversibility under magnetic force, and it has an indispensable impact on investigation of electronic devices.Originality/valueAn efficient numerical technique has been developed to solve this problem. The originality of this work is to analyse convective energy transport and entropy generation in a chamber with internal block, which is capable of maintaining heat and producing heat. Effects of irreversibility ratio are scrutinized for the first time. Analysis of convective heat transfer and entropy production in an enclosure with internal isothermal/heat generating blocks gives the way to predict enhanced heat transfer rate and avoid the failure of advanced technical systems in industrial sectors.

Radiative and dissipative MHD Eyring–Powell nanofluid bioconvective flow through peristaltic waves in the presence of bilateral chemical reaction with Arrhenius activation energy: Entropy optimization

The novel characteristics of nanofluids made them potentially important in the heat transfer mechanisms happening in industrial and medical processes, such as electronic devices, pharmacological techniques, hybrid combustion engines, thermal management of cars, refrigerator, chiller, temperature of gases reduction, and so on. In comparison to base fluid, these procedures have a propensity to improve thermal conductivity and convective transference of heat. This distinctive aspect has recently generated interest in nanofluids through various fluid flow models. The issue at hand involves the peristaltic flow of magnetohydrodynamics Eyring–Powell nanofluids through a microchannel containing oxytactic bacteria and nanoparticles. For a thorough analysis of irreversibility optimization, the analysis of entropy is additionally taken into consideration. To comprehend the flow physics associated with bolus formation and the effect of reflux on the micro vessel, a 3-D computational fluid dynamic analysis is performed. The effects of bilateral chemical interaction with nonlinear mixed convection and Arrhenius activation energy are considered in the present analysis. The complexity of the system was achieved through a numerical approach based on the concepts of small Reynolds number and large wavelength. The resulting nonlinear coupled differential equation system is solved numerically using the built-in command in MATHEMATICA (Parametric ND Solve Function). To perform a thorough comparative examination for various values of the considered sections of the channel, graphs have been used. Some of the investigation’s findings are the entropy profile has been improved for incremental values of Hartmann number and Brinkmann number whereas the axial velocity shows a downward trend for the highest values of the Hartmann number and the material fluid parameter.

Evaluation of the Thermal Performance of Two Passive Facade System Solutions for Sustainable Development

Sustainable development is essential for the future of the planet. Using passive elements, like ventilated facades based on insulation and air chambers, or living walls, which are solutions based on nature, is a powerful strategy for cities to improve their thermal environment, reduce energy consumption, and mitigate the effects of climate change. This approach allows for the quantification of the influence of passive surfaces on energy fluxes compared to bare surfaces. In addition, it delves into understanding how the incorporation of vegetation on building facades alters surface energy fluxes, involving a combination of physical and biochemical processes. This comprehensive investigation seeks to harness the potential of passive and natural solutions to address the pressing challenges of urban sustainability and climate resilience. This research uses a surface energy balance model to analyze the thermal performance of two facades using experimental data from a PASLINK test cell. This study uses the grey box RC model, which links continuous-time ordinary differential equations with discrete measurement data points. This model provides insight into the complex interplay among factors that influence the thermal behavior of building facades, with the goal of comprehensively understanding how ventilated and green facades affect the dynamics of energy flow compared to conventional facades. The initial thermal resistance of the bare facade was 0.75 (°C m2)/W. The introduction of a ventilated facade significantly increased this thermal resistance to 2.47 (°C m2)/W due to the insulating capacity of the air chamber and its insulating layer (1.70 (°C m2)/W). Regarding the modular living wall, it obtained a thermal resistance value of 1.22 (°C m2)/W (this vegetated facade does not have an insulating layer). In this context, the modular living wall proved to be effective in reducing convective energy by 68% compared with the non-green facade. It is crucial to highlight that evapotranspiration was the primary mechanism for energy dissipation in the green facade. The experiments conclusively show that both the modular living wall and open-ventilated facade significantly reduce solar heat loads compared with non-passive bare wall facades, demonstrating their effectiveness in enhancing thermal performance and minimizing heat absorption.

Thermal convective transport energy and environmental applications for magnetised flow with parallel (non-parallel) walls movement simulation of staggered cavity

Thermal convective transport energy and environmental applications for magnetised flow with parallel (non-parallel) walls movement simulation of staggered cavity

Thermal Study of the Utilization of Rice Husks Using the Forced Convection Method as Energy for a Rotating Cylinder Dryer

Small farmers in rural areas use the sun as their main energy source to dry post-harvest products. Due to limited knowledge and technology, farmers depend on the sun through direct drying. Direct use of the sun for the drying process has disadvantages in uncertain weather such as cloudy or rainy. This results in the drying process not being optimal or even stopping. This research aims to use rice husks as energy to replace direct sun drying to produce optimal temperatures so that drying time is shorter and the quality of the dried food is hygienic. Rice husk as an energy source is applied through a rotating cylinder dryer. This dryer is tailored to farmers' needs, namely easy to operate at an affordable price. This energy can be utilized sustainably because it is abundant through a forced convection system and energy conversion using a heat exchanger. The design of the compact rotary dryer includes an integrated drying chamber in one unit with the combustion furnace and a heat exchanger. The drying chamber includes a rotating cylinder and a fixed cylinder. The test results show that hot air from burning rice husks flows through the heat exchange pipes by conduction from the furnace to the walls of the drying chamber and by forced convection through an exhaust fan installed in the drying chamber. The average environmental temperature of 29.55-29.69oC has increased when using one exhaust fan to 64.46oC and two exhaust fans to 60.11oC. This drying temperature can produce shorter drying times, so it can be applied to post-harvest product drying, which is energy-efficient and sustainable for small farmers. Based on research results, rotating cylinder dryers powered by rice husks are very suitable for small farmers to replace direct sun drying.

Arrhenius activation energy effect in thermally viscous dissipative flow of micropolar material with gyrotactic microorganisms

The rheology of micropolar material with heat energy transport features is fully progressive, which allows considerable industrial and engineering applications. In this study, numerical analysis is presented to examine the micro-rotation characteristics of magnetized micropolar fluid flow towards the stagnation point region on a porous shrinking surface with gyrotactic microorganisms. To describe the convective energy transport features, Arrehenius activation energy, thermal radiation, Ohmic, and viscous dissipation effects are taken into consideration. The governing equations are converted into ordinary differential equations using appropriate similarity variables. The physical features of flow constraints are displayed and explained for velocity, thermal and solutal distributions, microorganism profile, as well as friction drag, couple stress, and energy transport rate. The results revealed that suction strength contributes to the increment of friction drag, couple stress, and energy transport rate, but the boosted values of the micropolar parameter lower the values of these physical quantities. For a specific range of the shrinking parameter, analysis confirmed the persistence of non-uniqueness solutions. Further, the microorganism profile declines as the bioconvection Lewis number and the bioconvection Peclet number increases. Additionally, according to time-dependent stability analysis, only the upper branch of solutions is physically stable, while the lower branch is not physically.