Papers by Dr R Velkennedy
Sustainable Development, 2022
In many cities, people were facing with serious problem of congestion and pollution due to heavy ... more In many cities, people were facing with serious problem of congestion and pollution due to heavy traffic. Transport is an important infrastructure for development. Traffic congestion is primarily influencing the city transportation. Due to traffic congestion the people were affected heavily by the delay and holding up time in signalized intersection. Some factors that influence the growth rate of motor vehicles are the increased population and also economic growth rate. Day by day Madurai city faces more transportation issues. Road network has been viewed as a major dynamic force in affecting quality of life. With growing population, demand for travel has consequently been increased. But the road conditions are arranged and intended for conventional traffic and increment in private vehicles lately are influencing the traffic management. Finding feasible route in the required time is a difficult problem for many people's particularly in emergency cases. So, the feasible routes ha...
Rapid urbanization and motorization congestion is a major problem that affects many aspects of th... more Rapid urbanization and motorization congestion is a major problem that affects many aspects of the city traffic. Due to increase of vehicles and congestion causes delay in traffic flow. A systematic education amongst vehicular travel time, vehicle flow and delay from moving car spectator technique in the field are presented. The moving car observer method were collected the data for 2 trials in both weekdays peak hours and non-peak hours and weekends peak hours and non-peak hours of vehicle count with and against the test vehicle, vehicle overtaken and overtaking the test vehicle, travel time and delay time were recorded. By the obtained information many parameters were calculated like flow, average journey speed, average journey time, average running speed. The graphical representation of average journey time, average delay time for weekday's peak hours and non-peak hours with weekend's peak hours and non-peak hours were done. The estimation of traffic volume and providing ...
Asset management is the way of managing assets optimally such that they serve throughout their de... more Asset management is the way of managing assets optimally such that they serve throughout their design life with minimal cost expenditure and maximum benefits for satisfying the organization's business goal. Railways are one of the major assets of the nation and nearly 4192.21 INR Billion capital investments have been made to Indian Railways (2012-2017, XII five year plan). Indian Railways contribute 2.5% to Gross Domestic Product of the country. Unfortunately the current financial health of Indian Railways is under crisis and corrective measure is the need of the era. Asset Management is widely been used by the Indian Railways but no specific framework has been framed separately for Indian Railways considering the Indian scenario. Hence, the role of Infrastructure Engineers greatly plays in improving this tool for the growth of the nation. In this study, major key cost drivers and sub-cost drivers identified by the international union of railways were studied and they were measu...
Roads are the major contributors to the socio-economic development of a nation helping in improvi... more Roads are the major contributors to the socio-economic development of a nation helping in improving connectivity. India has one of the largest road networks in the world with about 47 lakh km of road length. Transportation of over 60% of consumer goods and over 85% of passenger traffic happens on roads in India. In India, 2018-2019, the highest allocation of budget is towards road infrastructure, which helps in developing new roads and improving the condition of existing roads. India's urban population was around 377.11 million in the 2011 census. This rapid urbanization has also led to rapid motorization. Urban roads have a high volume of traffic making it necessary to install traffic signals at intersections for better control over the flow of traffic. Though urban signalized intersections helps in regulating the traffic flow in a shared space, it also acts as the zone of major congestions, accidents and increased levels of air pollution. In this study, a simulation of traffic...
En aquest article s'estudia la decoracio mural romanica de l'esglesia de Sant Marti Sesco... more En aquest article s'estudia la decoracio mural romanica de l'esglesia de Sant Marti Sescorts,1 tant els cinc fragments conservats al Museu Episcopal de Vic, dels quals destaquen els dos amb escenes del cicle d'Adam i Eva i, molt mes malmesa, l'escena de la caritat de sant Marti, com un altre fragment, amb el Pecat Original, que es coneix nomes per una fotografia anterior al seu arrencament. A mes, es ressalta que hi havia altres pintures del mateix conjunt, que tampoc ens han pervingut. Es a dir, es ressegueix criticament la historia dels frescos, que planteja molts interrogants. D'altra banda, la decoracio mural es confronta amb l'edifici del qual prove i fins on es possible se situa en el seu lloc. Tambe, s'examinen els dos cicles iconografics que decoraven l'absis, un veterotestamentari i un hagiografic, i, a partir del testimoni d'altres restes pictoriques, l'autora es pregunta si n'hi podria haver hagut un tercer, amb la historia de l...
Journal of Advances in Chemistry, 2017
In this study, the acid attack test is performed on the fiber reinforced concrete incorporating w... more In this study, the acid attack test is performed on the fiber reinforced concrete incorporating with manufactured sand silica fume and coconut shell. The grade of concrete is M50. Silica fume is partially replaced with 10 % by the weight of cement and manufactured sand is partially replaced with 40% by the weight of sand. The coconut shell is partially replaced for coarse aggregate by 20%. Additionally three types of fibers are used such as steel fiber, sisal fiber, and coir fiber. The volume fraction of fibers ranges from 0 to 3%. The aim of this study is to evaluate the acid resistance of the fiber reinforced high performance concrete. From the experimental investigation, it was found that there is improvement in acid resistance for fiber reinforced high performance concrete when compared to plain cement concrete. Also fiber reinforced concrete improves the cracking resistance compared to plain cement concrete.
Indian Journal of Ecology, 2018
Structural Concrete, 2020
In the recent past, there is an increased interest throughout the research community to minimize ... more In the recent past, there is an increased interest throughout the research community to minimize the production of ozone harming substances which directly affect global warming. Cement production and consumption emit 7% ozone‐depleting substances into the atmosphere consistently. In an attempt to address this challenge, one of the efficient decisions being employed as of late incorporates the utilization of geopolymer concrete (GPC). In this paper, metakaolin is viewed as the key component which is rich in silica and alumina, responsible for the strength and durability of the GPC mix product. It is exposed to varying compositions to discover the ideal compositions to find out the optimum loading that gives the best properties and performance to the GPC paver blocks. Additionally, nanosilica which reduces the pores is included little amounts to the optimized GPC mix to comprehend the additional impact it accommodates the advancement of the performance of GPC mix paver blocks. In order to examine the performance of GPC paver blocks, properties such as density, compressive strength, water absorption, and abrasion resistance were evaluated for different loading levels of metakaolin (10, 20, 30, and 40%) and nanosilica (0.5 and 1%) GPC mix samples. It is seen that 30% metakaolin and 0.5% addition of nanosilica give optimum results than other combination of materials in the GPC mix.
Nature Structural & Molecular Biology, 2021
Lecture Notes in Civil Engineering, 2021
IOP Conference Series: Earth and Environmental Science, 2021
The thermal distribution and fluid flow by natural convection inside a closed cool enclosure is s... more The thermal distribution and fluid flow by natural convection inside a closed cool enclosure is studied. A channel section is placed at the center of the compartment and its temperature is hot. Buoyancy flow is induced inside the enclosure due to the thermal variation. Air is considered as the fluid inside the enclosure and its Prandtl number is 0.71. The fluid is expected to obey Boussinesq approximation. To evaluate the flow, the streamline, isotherms, horizontal and vertical centerline velocity and Nusselt numbers were calculated. The flow is modified by changing the Rayleigh number from 103 to 106. The results show the influence of Rayleigh number on the flow pattern, velocity of fluid flow, and heat transfer rate. Computational fluid dynamics is used as the tool for this study.
Journal of Thermal Analysis and Calorimetry, 2019
Three-dimensional numerical simulation on natural convection inside the T-shaped cavity, filled w... more Three-dimensional numerical simulation on natural convection inside the T-shaped cavity, filled with water-based hybrid nanofluid of CNT-aluminum oxide is performed by vorticity-vector potential formalism. The variables considered are size of enclosure (0.1 \ L \ 0.9), volumetric percentage of nanoparticles (0 \ u \ 4%), fraction of CNT composites (0 \ fr \ 1), and Rayleigh number (10 3 \ Ra \ 10 6). The heat transfer is increased with the increase in size, volumetric percentage of nanoparticles, fraction of CNT composites, and Rayleigh number.
International Journal of Mechanical Sciences, 2018
Three dimensional numerical simulations have been performed on a cubical cavity using finite volu... more Three dimensional numerical simulations have been performed on a cubical cavity using finite volume method. Vorticity-vector potential formalism is enforced on the open cavity filled by the Aluminium Oxide/Water nanofluid. The cavity is heated up by the central isothermal block and the results of mixed convection and entropy generation are illustrated with particle trajectories, isotherms, Nusselt number and Bejan number. The considered parameters are Richardson number (0.01 to 100), block size (0.1L to 0.7L) and percentage of Al 2 O 3 particles (1 to 5%). It was found that the effect of adding nanoparticles on heat transfer is limited for small size hot block and low Richardson number and becomes important for higher values of L h and Ri. The thermal entropy generation increases by increasing the concentration of nanoparticles for all Richardson numbers, but the variation viscous entropy generation with concentrations depends on Ri values.
Advances in Materials Science and Engineering, 2016
The purpose of this study is to compare the ultimate load carrying capacity of conventional reinf... more The purpose of this study is to compare the ultimate load carrying capacity of conventional reinforced concrete beams with that of investigation specimen incorporated with coated reinforcement and partially with recycled aggregate and quarry dust. A novel technique of coated reinforcement delays the onset of corrosion with enhanced durability of structures. Results show that not even a film of corrosion (white rust) can be seen in the investigation specimen. There is a progressive increase in stiffness from the state of the first crack to ultimate stage and a negligible difference in ultimate load carrying capacity of the investigation specimen, when compared with the controlled specimen. Incorporation of galvanization, recycled aggregate, and quarry dust seemed to be compatible with the existing conservative concreting procedures. Experimental results are compared with the numerical solutions aided by finite element analysis (FEA by using ABAQUS).
Journal of Molecular Liquids, 2017
A finite difference based, two dimensional numerical analysis on the laminar natural convection i... more A finite difference based, two dimensional numerical analysis on the laminar natural convection inside the differentially heated C-shaped open cavity with an isothermal square block is presented using the vorticity-stream function approach. The enclosure is filled up with hybrid nanofluid of Cu-TiO 2 /water. The left vertical wall is assumed as hot and the right wall is considered as cold wall. All the horizontal walls at the top and bottom are considered as adiabatic. The inlet port is located on the top right portion and the outlet is placed at the bottom right portion of the C shaped cavity. The square isothermal block of size L/5 is placed at the middle of the web of the cavity. The variables considered are Rayleigh number (10 4 to 10 6) and the solid hybrid particles (0 to 5%). The physics of the fluid flows with a single phase model are illustrated with streamlines, isotherms and average Nusselt number. When Rayleigh number increases, the strength of the primary vortex diminishes. Heat transfer enhanced monotically with the increase in percentage of hybrid nano composites at Ra = 10 4 and 10 5 .
International Communications in Heat and Mass Transfer, 2015
ABSTRACT A finite difference based numerical study of two dimensional laminar natural convection ... more ABSTRACT A finite difference based numerical study of two dimensional laminar natural convection inside the open rectangular forward stepped enclosure with sinusoidal time-variant temperature on the top wall is presented by vorticity–stream function approach. The enclosure is divided by a vertical partition at the middle with a central opening. The aspect ratio of the enclosure is 1.6. The top wall is constructed with a step of 20% of height of the enclosure. Except the top wall, all the outer walls are assumed as hot and maintained at constant temperature. The parameters governing the study are the amplitude (0 < a < 0.5) and the period (0.001 < t < 0.8) of the variable temperature, the Rayleigh number (104 < Ra < 106), Prandtl number (Pr = 0.71), and the step. The effect of the amplitude and period on the heat transfer inside the enclosure is examined for constant temperature (a = 0) and varying temperature (a ≠ 0 and t ≠ 0). The details of fluctuating flow and temperature fields are analyzed and the periodic results are elucidated with streamlines, isotherms and Nusselt number. The result indicates that the heat transfer increases with increasing amplitude and decreases with increasing period of oscillating temperature on the top wall. The heat transfer increases when buoyancy is increased through Rayleigh number. The provision of step increases the heat transfer on the right side of the upper wall due to the increasing buoyancy.
Numerical Heat Transfer, Part A: Applications, 2014
Highlights A numerical study is presented to examine the melting process of PCM using LBM. Th... more Highlights A numerical study is presented to examine the melting process of PCM using LBM. The melting process is simulated considering the natural convection effect. Immersed boundary condition is implemented to cover solid-liquid momentum exchange. Velocity and temperature fields are obtained using the multi relaxation time model. Results show that the movement of solid body, accelerates the melting process.
International Communications in Heat and Mass Transfer, 2014
Finite difference based numerical studies of steady laminar natural convection inside the open sq... more Finite difference based numerical studies of steady laminar natural convection inside the open square enclosure with protrusions are presented. The fluid considered is air with a Prandtl number of 0.71. The buoyancy enabled cold air flows from bottom-left vertical wall to the diagonally opposite top-right vertical wall crossing the obstacles in the form of a partition and transverse baffles. All the external peripheral walls are considered as hot and the interior cross walls are assumed as cold. The effect of obstacles on the heat transfer is numerically investigated. The convective heat transfer mechanism is enhanced further through the Rayleigh number by varying Ra as 10 3 , 10 4 and 10 5. The subtle variation in buoyancy, momentum, hydrodynamic blockage and protrusions influences the formation, size and geometry of the vortices and also influences the heat transfer intensities inside the enclosure. The intriguing physics is elucidated with streamlines, isotherms, Local Nusselt number and velocity profiles. The study reveals that the introduction of cold baffle intensifies the heat transfer inside the enclosure irrespective of its position and length. The hydrodynamic blockage effect is dominant when the transverse baffle is positioned on the right side of the partition.
Arabian Journal for Science and Engineering, 2014
A finite difference-based numerical study of steady laminar natural convection inside the ventila... more A finite difference-based numerical study of steady laminar natural convection inside the ventilated square enclosure having two square cylindrical blocks placed diagonally is presented. The fluid considered is air with a Prandtl number of 0.71. The buoyancy enabled cold air flows from bottom of the left vertical wall to the diagonally opposite top of the right vertical wall by passing the protrusions in the form of two conductive square blocks placed across the through flow. All the exterior circumferential walls are considered as hot. The convective heat transfer inside the enclosure with the different sizes of square blocks is numerically analyzed. The convective heat transfer mechanism inside the enclosure is further modified through the Rayleigh number as 10 4 , 10 5 and 10 6. The hydrodynamic block effect due to the square blocks affects the formation and geometry of the vortices and also influences the heat transfer intensities across the enclosure. The hydrodynamic blockage has huge effect on the downstream side of the block than the upstream side. The size of the blocks has great impact on the intensity of heat transfer. The complex physics is illustrated with streamlines, isotherms, local Nusselt number and velocity profiles.
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Papers by Dr R Velkennedy