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In an indoor kitchen environment, proper installation of supplying air system is essential for maintaining optimal human thermal comfort level. Current thermal comfort investigation has been accomplished during "various cooking periods (breakfast, lunch, snacks, dinner)" inside the air‐conditioned kitchen environment of railway pantry car in India. The study goals to improve thermal comfort inside the pantry kitchen by implementing proper installation of the supply air system. A field experiment and computational fluid dynamics approach has been carried out during the summer season. Also, standard effective temperature (SET) index was utilized to determine the thermal comfort status. Three proposed design modified cases of pantry cars (based on supplying air system concepts) have been executed followed by validation and comparison with the existing case model. Results revealed modified Case III as a better design concept (indicating better air supply circulation and temperature decrease at the desired location) compared to the existing and other two proposed cases. Simultaneously, the SET index range was 26.5–28.6°C; indicating "comfortable thermal sensation throughout the cooking period." This study's outcomes suggest improvements in thermal comfort and energy savings of "air‐conditioned" pantry car kitchens in "Indian Railways" that could be referred directly. [ABSTRACT FROM AUTHOR]

The Indian River, which is celebrated for its breathtaking beauty and diverse heritage of cultures, has an extensive amount of potential for producing green hydroelectric electricity. 7.5 % of the world's energy came from renewable sources in 2022, with India making up 36 % of the share and growing. India has nearly reached the 5 GW objective for small hydro projects and has reached 68 % of its 175 GW renewable energy ambition. At 90 % efficiency, bulb turbines are hydroelectric turbines that produce power from water, making them a perfect choice for high flow rates and low water head conditions. In order to optimize bulb turbines, this research investigates the use of computational fluid dynamics (CFD) to assess variables including the number of guiding vanes, the angle of the draft tube, and the design of the blades. According to studies, efficiency is increased when guiding vanes increase. The geometry of guiding vanes also has a significant impact on performance. Draft tubes, which restore kinetic energy from water entering the turbine, can enhance efficiency with proper design. Adding anti-cavitation capabilities to runner blades improves performance even further. CFD models verify these conclusions, with little variations from the field data. By fine-tuning important parameters such as 14 guiding vanes and adjusting the draft tube angle to 2.5°, the turbine's efficiency jumped from 87 % to 97 %. [ABSTRACT FROM AUTHOR]

The thermal management system of battery pack was investigated based on the combination of two different phase change materials OM35 and Paraffin wax coupled with forced air cooling to maintain the thermal distribution in the battery pack at a discharge rate of 1C. Numerical investigations were carried out by computational fluid dynamics (CFD) to understand the effects of battery thermal characteristics on environmental conditions in different cities of India. Furthermore, the thermal behavior of the system in an active and passive cooling was analyzed. The result indicates that active cooling can reduce the temperature rise in the battery pack by 2.8°C in the discharge cycle. The above studies identified active cooling not always required when the vehicle speed increases above 40 km/h. Environmental conditions during summer have a significant impact on the temperature rise in the battery pack. [ABSTRACT FROM AUTHOR]

The global warming challenge is mostly the cause of floods today. Individuals everywhere in India had to deal with the impact of fluid load affecting bridges in the last 30 years. The latest methodology analyzed is a Finite Volume Technique (F.V.M.). In this research, actual dimensions of the bridge are used and for this, the data is collected from the Government of Maharashtra public works department (PWD Miraj). Also, Indian standard codal equations for pressure exerted on bridge pier are compared. For bridge pier modelling, square and circular segments are assessed. In addition to bed and sidewalls, consideration was given to simplifying the nonslip boundary of the stream for the fluid zone. The dimension of the fluid domain is 21 m x 23 m x 21.145m and the size of the pier is 1.5 m x 1.5 m. A numeric model with a water rate from 0.5 m/sec to 10 m/sec is established to test the impact of hydrodynamic pressure on the platform. The configuration conditions by all pier models are the same. Concerns about the effects of fluid flowing through a pier surface and pressure circulation combined with pier height are essential for this research. This study emphasizes that AS5100, I. R. C. 6, I. R. S. technique is ideal for a suitable conservative measurement of the pressure in square cross-section, but has a harmful margin of protection for circular cross-section bridge piers and hence can be used cautiously. [ABSTRACT FROM AUTHOR]

Coal mining plays a significant role in the economy of India. The health and safety of miners working in underground mines is a serious concern. One of the risk factors is with regard to the ventilation systems. Computational fluid dynamics is one of the major tools used to study the air-flow distribution. It helps in understanding the blind galleries which may need adequate ventilation. It also helps suppress the spontaneous heating of poorly ventilated workings and in generating heat-stress plots inside the galleries to ensure the safety of mineworkers. [ABSTRACT FROM AUTHOR]

Purpose -- Heat gain in buildings occurs due to heat transfer through the building fabric or envelope, especially the walls and roof. The purpose of this paper is to identify and recommend the suitable wall materials for better thermal performance in buildings in warm and hot climatic zones of India. As India lies between the tropic of cancer and the equator, the solar radiation from the sun falls more on the walls than the roofs of the buildings. Thus, it is imperative to protect the walls from heat gain to promote thermal comfort in naturally ventilated buildings and reduce the energy loads due to artificial cooling systems in air-conditioned buildings. Design/methodology/approach -- In this paper, an investigation of heat flow characteristics in steadystate and the transient state for five different uninsulated wall structures using computational fluid dynamics (CFD) software has been carried out. The climate conditions at Madurai, India have been considered for this study. Findings -- The findings of the study revealed that aerated autoclaved concrete (AAC) and hollow clay blocks (HCB) for external walls in naturally ventilated buildings in warm climatic regions could improve the building's thermal performance index and reduce peak indoor operative temperature by about 6°C--7°C. The results of steady-state and transient state analysis were found to be in good agreement with the results of the reviewed literature. Research limitations/implications -- Over the past few decades, only very few architects and builders have been successful in influencing their clients to accept alternate materials such as AAC blocks, HCB, stabilized earth blocks, adobe blocks, fly-ash bricks as an alternate to conventional bricks in an attempt of highlighting their benefits, such as; materials that are easily available, more energy-efficient, can withstand the extreme weather conditions, promote thermal comfort and cost-effective. This paper provides strong evidence that AAC and HCB blocks are the most appropriate materials for improving the thermal performance of envelope walls in regions where the outdoor temperatures are above 40°C. Originality/value -- This paper has made an attempt to identify the appropriate wall materials for effective thermal performance in warm and hot climates. A comparative analysis between five different wall types under the existing solar conditions has been analyzed using CFD simulation study in steady-state and transient conditions under summer conditions and the appropriate wall materials have been suggested. There has been no attempt carried out so far to analyze the thermal performance of different walls using 24 h transient approach in CFD. [ABSTRACT FROM AUTHOR]

Currently demand of Indian budget cars also called people's car in India is in great demand and around 1 million cars have been sold in the last financial year with 12% increase of sales in every forthcoming year. These are categorized in sub 4m category of sedan, hatchbacks and medium size SUVs' and their price ranges between 7 to 11 lakhs. The aerodynamics significantly affects the performance of the vehicle particularly at high speed. The manufactures are more focused on styling and giving a luxury look and other features of the car which sometimes make them to compromise on its aerodynamic design. This may lead to increase in fuel consumption at Indian road conditions. A cost-effective way to reduce fuel consumption, drag coefficient, lift force is to improve aerodynamic behavior and reduce the aerodynamic drag. The software used in this work is Solidworks, Ansys Fluent and commercial CFD post. Consequently, of using this software, it allows us to apply, learn and link technical knowledge of aerodynamics and computer knowledge. [ABSTRACT FROM AUTHOR]

Open drying is practiced for drying Capsicum frutescens in the cottage industries of India. In order to improve drying, an experimental set-up of solar rack dryer is constructed and studied different heat transfer augmentation techniques. A passive heating coil extended from the header of a water-in-glass evacuated tube coupled with parabolic trough is used to augment the heat in the collector section of the dryer. The drying rate in rack dryer is found to be 62% higher than that of open air drying of green chillies. Moreover, the drying rate in augmented rack dryer is found to be 7% higher than that of rack dryer. In addition to this, an effective design for the dryer cabinet with respect to air circulation is arrived through computational fluid dynamics analysis. Through this new design, the drying rate is improved further by 3%. Based on energy analysis, the specific energy consumption during the drying of this particular product using the augmented dryer is found to be 1.27 kWh/kg. The exergy efficiency of the drying chamber is found to be in the range of 4%-45% with an average of 16% for Capsicum frutescens. [ABSTRACT FROM AUTHOR]

Flexible, sand-filled, geotextile bags (geobags) have been used in both India and Bangladesh along the banks of the Brahmaputra for protection against riverbank erosion. Geotextile containers have been researched extensively for their use in coastal structures; however, there is a gap in knowledge of the application of smaller geobags used in riverbank protection structures. In 2018, flume experiments (scaled 1:7) were performed to study the incipient motion of geobags and the methodology for sizing geobags. Building on the data collected from the flume experiments, numerical models have been employed to gain further insight into the hydraulic forces acting on the bags. The numerical models have been created using ANSYS CFX. While there is not enough data to obtain a Shields parameter which can be used for design purposes, initial estimates find the Shields value for geobags lies around 0.09, which is much larger than the value for rocks, around 0.045. The results from this study suggest that the Shields parameter varies with fill percentage of the bags. This paper also presents first results on the roughness of underwater geobag aprons. • Building on data collected from flume experiments, numerical models have been employed to gain further insight into the hydraulic forces acting on geobags. [ABSTRACT FROM AUTHOR]

A walk-in type 222Rn calibration chamber (~ 22 m3) is established at the Centre for Advanced Research in Environmental Radioactivity (CARER), Mangalore University, India which is being used by research groups working on 222Rn in India and other countries as well. In recent times, computational fluid dynamics (CFD) technique is opted as an alternative approach for the prediction of 222Rn concentration profile in the closed domain. CFD simulations were carried out to study the transient build-up and spatial behavior of 222Rn concentration in the calibration chamber. Measurements were performed using active 222Rn measuring devices and results of the CFD predictions and direct measurements were compared. A good agreement was observed between the simulated and experimental results with deviation between the two entities being ~ 3% in the case of transient build up and ~ 8% in the case of spatial distribution of 222Rn concentration. [ABSTRACT FROM AUTHOR]

Solar food drying is a well-established food-conserving process in India. Various researchers had developed solar dryer models which were usually validated using experimental observations and numerical simulation processes that are time-consuming and money-consuming. Computational fluid dynamics (CFD) simulation software facilitates the simulation of the models and gives same results in a comparatively small frame of time. This research paper is focused on CFD simulation, validation of design, energy analysis and numerical computation for domestic direct-type solar dryer for which experimental observations were performed at Ludhiana in November 2006. The design and simulation of the domestic direct-type multi-shelf dryer at no load condition are performed using ANSYS Fluent 14.0 software. The temperature of the air inside the dryer is found to be 326 K, which validates the design and purpose of the domestic direct-type multi-shelf dryer. The embodied energy of the constituents used in the construction of dryer is obtained as 339.015 kWh, and the energy payback time and carbon credit are found to be 7.57 years and INR 2055, respectively. The convective heat transfer coefficient for the dryer varies from 2.4 to 2.8 W m−2 °C−1. Coefficient of determination is estimated to be 0.98 under no load condition which shows the fare agreement between predicted and experimental value. [ABSTRACT FROM AUTHOR]

In this study, we attempt to mitigate household air pollution (HAP) through improved kitchen design. Field surveys were conducted in ten kitchens of rural western India, which were then modelled and simulated for dynamic indoor airflow network analysis. The simulated results were statistically clustered using principal component analysis and hierarchical agglomerative clustering, to construct a cumulative built environment parameter called 'Built Factor' for each kitchen, and subsequently a derivative matrix was developed. Categorization of better performing kitchens from this derivative matrix enabled in deriving the built parameter thresholds for a 'better' kitchen design. This derived kitchen showed 60 % reduction in PM2.5 peak concentration during cooking hours. The evaluation described here is essentially a 'proof of concept', that effective building design can be an alternative way to reduce HAP without the introduction of chimneys, improved cookstoves or shifting to cleaner fuel. [ABSTRACT FROM AUTHOR]

Methane-based inflammable underground coal mine environment has led to catastrophic losses in the past. Migration of methane from the working seam and desorption region above and below the seam causes explosion hazard. In this study, the computational fluid dynamics (CFD)-based simulations of a longwall panel in a methane-rich inclined coal seam of the Moonidih mine in India established that the ventilation parameters greatly influence the methane flow in the longwall tailgate and porous medium of the goaf. The field survey and CFD analysis revealed that methane accumulation on the "rise side" wall of the tailgate is attributable to the geo-mining parameters. Further, the turbulent energy cascade was observed to impact the distinct dispersion pattern along the tailgate. The numerical code was used to investigate the changes in ventilation parameters made to dilute the methane concentration in the longwall tailgate. Methane concentration in the tailgate outlet decreased from 2.4 to 1.5% as the inlet air velocity increased from 2 to 4 m/s. The oxygen ingress into the goaf increased from 0.5 to 4.5 lps as the velocity was increased, causing the explosive zone in the goaf to expand from 5 to 100 m. Amongst all velocity variations, the lowest level of gas hazard was observed at an inlet air velocity of 2.5 m/s. This study, thus, demonstrated the ventilation-based numerical method to assess the coexistence of gas hazard in the goaf and longwall workings. Moreover, it provided impetus to the necessity of novel strategies to monitor and mitigate the methane hazard in U-type longwall mine ventilation., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Abstract: Thermal performance of earth air tunnel heat exchanger (EATHE) under transient operating conditions has been evaluated for predominantly hot and dry climate of Ajmer (India) using experimental and computational fluid dynamics modeling. Effect of time duration of continuous operation and thermal conductivity of soil on thermal performance of EATHE under transient conditions has been analyzed. Results show that the transient thermal performance of EATHE is significantly dependent on thermal conductivity of the soil and duration of its continuous operation. Under steady state condition, a drop of 18.8°C is obtained in air passing through EATHE having 0.1m diameter and 60m length, at 5ms−1 flow velocity, whereas, the transient analysis shows that for soil having thermal conductivity of 0.52Wm−1 K−1, the cooling of air reduces from 18.7°C to 16.6°C, after 24h of continuous operation. Change in cooling effect after 24h of operation for soil thermal conductivity of 2.0Wm−1 K−1 and 4.0Wm−1 K−1, reduced from 18.8°C to 18.5°C and 18.8°C to 18.7°C respectively. The analyzed cases have shown the range of derating to be as minimal as 0% to as high as 64%, which if ignored while designing may lead to poor performance of earth air heat exchangers. [Copyright &y& Elsevier]

Abstract: Thermal performance of Earth Air Tunnel Heat Exchanger (EATHE) under transient operating conditions in winter season has been evaluated for predominantly hot and dry climate of Ajmer (India) using experimental and Computational Fluid Dynamics (CFD) modeling. Effect of time duration of continuous operation and thermal conductivity of soil on thermal performance of EATHE under transient conditions has been analyzed. Results show that the transient thermal performance of EATHE is significantly dependent on thermal conductivity of the soil and duration of its continuous operation. Under steady state condition, a rise of 19.6°C is obtained in air passing through EATHE having 0.1m diameter and 60m length, at 5m/s flow velocity, whereas, the transient analysis shows that for soil having thermal conductivity of 0.52Wm−1 K−1, the heating of air reduces from 19.4°C to 17.2°C, after 24h of continuous operation. Heating effect after 24h of operation for soil thermal conductivity of 2.0Wm−1 K−1 and 4.0Wm−1 K−1, reduced from 19.6°C to 19.2°C and 19.6°C to 19.5°C, respectively. The analyzed cases have shown the range of derating to be as minimal as 0% to as high as 64%, which if ignored while designing may lead to poor performance of earth air heat exchangers. [Copyright &y& Elsevier]

Abstract: Thermal performance of Earth Air Tunnel Heat Exchanger (EATHE) under transient operating conditions has been evaluated for predominantly hot and dry climate of Ajmer (India) using experimental and Computational Fluid Dynamics modeling. Effects of time duration of continuous operation, thermal conductivity of soil pipe diameter and flow velocity on thermal performance of EATHE under transient conditions have been analyzed. Results show that the transient thermal performance of EATHE is significantly dependent on thermal conductivity of the soil and duration of its continuous operation. The analyzed cases have shown the range of derating to be as minimal as 0% to as high as 64%, which if ignored while designing may lead to poor performance of EATHE. Study reveals that the effect of pipe diameter due to prolonged use of EATHE system on its thermal performance is least in case of soil with higher value of thermal conductivity. Results show that the increase in flow velocity leads to deterioration in thermal performance of EATHE system. Under steady state condition, drop of 18.8°C in air temperature is obtained, whereas, under transient conditions cooling of air reduces from 18.7°C to 16.6°C for soil thermal conductivity of 0.52Wm−1 K−1, after 24h of continuous operation. [Copyright &y& Elsevier]

Abstract: Component failures due to excessive flow-induced vibration are still affecting the performance and reliability of nuclear power stations. Tube failures due to fretting-wear in nuclear steam generators, and vibration related damage of reactor internals are of particular concern. In the Indian nuclear industry, flow induced vibrations are assessed early in the design process and the results are incorporated in the design procedures. In this paper the details of flow induced vibration studies on internals like liquid zone control unit and poison injection units of heavy water filled calandria of 700MWe Indian pressurized heavy water reactor is given. This includes computational fluid dynamics studies from which the velocities are extracted for the components lying inside the calandria. With these velocities as input, further studies are performed to predict the dynamic behavior of these components. Results of these calculations as well as conclusions derived from this investigation are presented. Based on the studies it has been established that flow induced vibration is not a concern in the present design of 700MWe calandria internals. [Copyright &y& Elsevier]

Summary: The world’s largest dew and rain collecting system, comprised of ridge-and-trough modules, was constructed in March 2006 at Panandhro in the semi-arid area of Kutch (NW India). The main goals were (i) to collect dew on a scale that could be beneficial to the local population (ii) to determine the efficiency of this new module shape, (iii) to determine whether results obtained from small measurement condensers can be projected to large condensers, (iv) to apply a computational fluid dynamic simulation to improve the condenser set-up. Preliminary studies performed with four standard plane condensers of 1m2 surface area, inclined 30° from horizontal, identified Panandhro as a promising site. The cumulated dew water during 192days was 12.6mm with a maximum of 0.556mm/night. A large dew condenser (850m2 net total surface) was designed with 10 ridge-and-trough modules. The ridges are trapezoidal, 33m long, 0.5m wide at the top, 2.2m wide at the base and sloping 30° from horizontal. The depth of the troughs between the ridges is 0.5m. A 2.5cm thick polystyrene foam rests on the surface as insulation with a radiative foil on top (similar to that developed by OPUR, see www.opur.fr). Numerical simulations using the computational fluid dynamic software PHOENICS were performed. The most profitable orientation was with the condenser oriented back to the wind direction, a configuration that lowers the wind velocity near the foil due to the combination of free convection and wind recirculation flows. A comparison of water yields over one year of measurements between four 1m2 plane condensers and a 850m2 ridge condenser showed a 42% lower yield on the large condenser. The difference is attributed mainly to folds in the plastic foil allowing water to fill the central ridge, thus decreasing radiative cooling. The output for 2007 was 6545L, corresponding to 7.7mm/day on average. The largest event was 251.4L/night (0.3mm). Such a condenser can also collect rain (and, to a lesser extent, fog). Chemical and biological analyses showed that dew water, once filtered and bottled, could be used for drinking after a light treatment to increase the pH. The price of this water could be lowered to reach 30% (dew only) or even 3% (dew plus rain) of the market prize. [Copyright &y& Elsevier]

Abstract: The management of hydrogen in a Nuclear Reactor Containment after LOCA (Loss Of Coolant Accident) is of practical importance to preserve the structural integrity of the containment. This paper presents the results of systematic work carried out using the commercial Computational Fluid Dynamics (CFD) software FLUENT to assess the concentration distribution of hydrogen in a typical Indian Nuclear Reactor Containment. In order to obtain an accurate estimate of hydrogen concentration distribution, a suitable model for turbulence closure is required to be selected. Using guidelines from the previous studies reported in the literature and a comparative simulation study using simple benchmark problems, the most suitable turbulence model for hydrogen mixing prediction was identified. Subsequently, unstructured meshes were generated to represent the containment of a typical Indian Nuclear Reactor. Analyses were carried out to quantify the hydrogen distribution for three cases. These were (1) Uniform injection of hydrogen for a given period of time at room temperature, (2) Time varying injection as has been computed from an accident analysis code, (3) Time varying injection (as used in case (2)) at a high temperature. A parametric exercise was also carried out in case (1) where the effect of various inlet orientations and locations on hydrogen distribution was studied. The results indicate that the process of hydrogen dispersal is buoyancy dominated. Further for typical injection rates encountered following LOCA, the dispersal is quite poor and most hydrogen is confined to the fuelling machine vault. [Copyright &y& Elsevier]

A review of the emergence and maturing of computational fluid dynamics (CFD) research in India over the last four decades is presented. The status of in-house developed CFD codes in various aerospace laboratories and academic institutions in the country is described along with their strengths and weaknesses. Although, some level of maturity is achieved in CFD to address the external flow problems of an aerospace vehicle, the slow growth of indigenous reacting CFD codes forced Indian aerospace industry to depend solely on the commercial software for addressing the internal flow problems related to propulsion and combustion. A brief account of various technical and managerial issues in CFD development is presented. A roadmap is proposed for the graduation of CFD codes, from analysis tool to design tool. [ABSTRACT FROM AUTHOR]

The role of computational fluid dynamics (CFD) in the design of fighter aircraft, transport aircraft, launch vehicle and missiles in India is explained. Indigenous developments of grid generators, 3-D Euler and Navier- Stokes solvers using state-of-the-art numerical techniques and physical models have been described. Applications of these indigenous softwares for the prediction of various complex aerodynamic flows over a wide range of Mach number, angle of attacks, are presented. Emergence of CFD methods as an efficient tool for aerospace vehicle design is highlighted. [ABSTRACT FROM AUTHOR]

The paper addresses the design optimization of the radiation chamber of Sludge Hygenization Research Irradiator (SHRI). The distribution and placement of source assembly are the parameters of optimization. The physical parameters that are associated with radiation effects are the absorbed dose rate, the dose distribution and radiation quality. The objective of the present study is to achieve increased average absorbed dose rate with improved distribution by minimal alteration in the geometry of the existing SHRI that was designed by the Bhabha Atomic Research Centre and installed in Vadodara, India. A new approach is proposed to evaluate the time averaged absorbed dose rate and is validated. A better design for the arrangement of source assembly inside the irradiator vessel of SHRI has been proposed. [ABSTRACT FROM AUTHOR]

This article presents the computational flow analysis of an axial-centrifugal flow system used for transformer oil cooling in WAP-5 and WAP-7 electric locomotives of Indian Railways. The commercial computational fluid dynamics code 'FLUENT' was used for the numerical simulation of the flow system. A standard k-ϵ turbulence model was employed for turbulence modelling. The flow field through the impeller was analysed to investigate the effect of blade twists and to determine the forces on the blades. A modified impeller design is suggested whose diameter is less than the existing one, which helps in reducing the centrifugal forces. The flow field analysis of the modified impeller shows improvement in the flow through the impeller channels with better performance and reduction in forces on the blades. [ABSTRACT FROM AUTHOR]

• Arsenic-contaminated water is a major public health issue in India and Bangladesh. • Laterite soil provides a novel and cost-efficient way of removing arsenic from water. • A mathematical model determines filter lifetime and an upscaling protocol. • The model captures the filter behaviour through three simple parameters. • The model plays an essential role in the filter deployment and maintenance. Arsenic is among the most hazardous contaminants present in drinking water. Recent increase in agricultural growth and fertiliser use in India and Bangladesh has led to the release of naturally occurring arsenic from the rocks, creating a major public health issue. A novel technology has been developed using naturally abundant laterite soil to filter arsenic, providing potable water to more than 5000 people. To upscale this technology and realise its full potential, a comprehensive understanding of the dependence of filter life on operating regime (flow rate, arsenic concentration and filter size) is essential. We present a mathematical model that characterises arsenic removal, circumventing the need for time-consuming experiments. The model incorporates inter- and intra-particle mass transport within the filter medium. The resulting model enables prediction of a filter lifetime in a specified role, such as on a domestic or community scale, and should assist in future filter deployment and maintenance. [ABSTRACT FROM AUTHOR]

The article offers information on the refresher course in theoretical and computational fluid dynamics, sponsored by the Indian Academy of Sciences, Indian National Science Academy, and The National Academy of Sciences in India from August 27 to September 8, 2012.