Department of Mechanical Engineering

Indian Institute of Technology Palakkad&nbsp;(IIT Palakkad or IIT PKD) is a public autonomous&nbsp;engineering&nbsp;and&nbsp;research&nbsp;institute located in&nbsp;Palakkad,&nbsp;Kerala. It was&nbsp;one of the five new&nbsp;IITs&nbsp;proposed in the&nbsp;2014 Union budget of India. The campus was inaugurated on 3 August 2015. The institute has 94 faculty, 978 students, and 63 non-teaching staffs.

IT Palakkad currently offers four-year Bachelor of Technology (B.Tech) and two years MS programmes in 8 different engineering disciplines including&nbsp;Computer Science, Electrical, Mechanical, Civil among others.

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IIT Palakkad

Computational electrodynamics (CED), the numerical solution of Maxwell's equations, plays an incredibly important role in several problems in science and engineering. High accuracy solutions are desired, and the discontinuous Galerkin (DG) method is one of the better ways of delivering high accuracy in numerical CED. Maxwell's equations have a pair of involution constraints for which mimetic schemes that globally satisfy the constraints at a discrete level are highly desirable. Balsara and Käppeli (2019) presented a von Neumann stability analysis of globally constraint-preserving DG schemes for CED up to fourth order. That paper was focused on developing the theory and documenting the superior dissipation and dispersion of DGTD schemes in media with constant permittivity and permeability. In this paper we present working DGTD schemes for CED that go up to fifth order of accuracy and analyze their performance when permittivity and permeability vary strongly in space. Our DGTD schemes achieve constraint preservation by collocating the electric displacement and magnetic induction as well as their higher order modes in the faces of the mesh. Our first finding is that at fourth and higher orders of accuracy, one has to evolve some zone-centered modes in addition to the face-centered modes. It is well-known that the limiting step in DG schemes causes a reduction of the optimal accuracy of the scheme; though the schemes still retain their formal order of accuracy with WENO-type limiters. In this paper, we document simulations where permittivity and permeability vary by almost an order of magnitude without requiring any limiting of the DG scheme. This very favorable second finding ensures that DGTD schemes retain optimal accuracy even in the presence of large spatial variations in permittivity and permeability. We also study the conservation of electromagnetic energy in these problems. Our third finding shows that the electromagnetic energy is conserved very well even when permittivity and permeability vary strongly in space; as long as the conductivity is zero. © 2019 Elsevier Inc.

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Journal of Computational Physics

Globally constraint-preserving FR/DG scheme for Maxwell's equations at all orders

Methane hydrate reservoirs are a potential alternative energy source identified in the recent years. This work develops a methodology to predict the gas production potential and hydrological transport properties of methane hydrate reservoirs using artificial neural network coupled with genetic algorithm. Hydrate dissociation due to depressurisation in a lab scale core recovered from field excavation is modelled as multi-component, multi-phase, chemically reacting, non-isothermal flow in porous medium with effective transport properties. A predictive surrogate model, mimicking the full scale model along with reservoir heterogeneity is then developed using a feed forward back-propagation artificial neural network trained using the Levenberg-Marquardt algorithm coupled with Bayesian regularization. Predictions of gas production potential obtained from the surrogate model are then compared with those obtained from the full numerical simulations as well as measurements reported in literature for prescribed values of hydrological transport properties. It is then interfaced with genetic algorithm to solve an inverse estimation problem involving prediction of reservoir hydrological properties namely porosity, intrinsic permeability and initial hydrate saturation from temporally varying gas production. The effect of uncertainties associated with measurement of gas production on the predicted hydrological properties is investigated numerically and suitable bounds are proposed based on a statistical analysis. © 2019 Elsevier Ltd

Thermal Science and Engineering Progress

Prediction of gas production potential and hydrological properties of a methane hydrate reservoir using ANN-GA based framework

Flame jet impingement heat transfer is a well-established technique for obtaining high heat transfer rates in many domestic and industrial applications. The flame structure and the heat transfer characteristics of the impinging methane diffusion flame and partially premixed flame are experimentally investigated. The heat transfer characteristics of the impinging methane flame are determined using the minimization technique wherein the target surface is impinged by a methane flame from the bottom and is simultaneously cooled from the top by air jets of different Reynolds number. At steady state, one-dimensional energy balance across the impingement surface provides an over-determined system of equations which when solved using the minimization technique give the heat transfer coefficient of the flame jet, the reference temperature and the emissivity of the gas/flame beneath the impingement surface. The stagnation point heat transfer coefficient and reference temperature are found to be maximum for the case of flame just touching the impingement surface. The radial variation of the non-dimensional heat transfer coefficient and reference temperature is found to have a Gaussian profile. For low H/d's where the flame is impinging the target surface, the temperature at the stagnation zone is lower than in the radial position as the hot jet turns in the radial direction and impinges at a distance slightly away from the stagnation region. The separation of heat transfer components indicates that the heat transfer is convective dominant with radiation accounting to 10% of the total incident heat flux in the case of methane diffusion flame and 3.5% in the case of partially premixed flame. Re-radiation becomes a significant component of heat transfer, accounting to 25–30% of the incident heat flux, due to higher wall temperatures. The present study also investigates the effect of tube burner to plate spacing. © 2018 Elsevier Ltd

International Journal of Heat and Mass Transfer

Heat transfer characteristics of impinging methane diffusion and partially premixed flames

The underwater robotic vehicle presented here is inspired by an Ostraciiform form of swimming with three oscillatory fins to propel itself and control its orientation. A mathematical model is made to simulate the motion of the vehicle based on the fin oscillations to aid in the real-time vehicle control. The model predicts the forces produced by the oscillating rigid fins in the water. A new motion control approach for an underwater robot is proposed and investigated. In this paper, the oscillating fin arrangement is under-actuated and carries out four degrees of freedom (DOF) motion with three fins. The threes fins include: once caudal fin and two pectoral fins. The dynamic model developed for the robot has a highly nonlinear thrust vector map because of the thrust generation from these oscillation angles. Nonlinear control methods such as Backstepping control is applied to this robot model due to the continuous oscillatory motion of fins for achieving different DOF. Contrary to the feedback linearization technique which cancels potentially useful nonlinearities, this control scheme avoids the cancellation; resulting in a less complicated controller. Lyapunov stability theory was used to prove the system stability. RMS values of the error were used for tuning the controller gains constants. © 2019. The Authors. Published by Elsevier Ltd. All rights reserved.

IFAC-PapersOnLine

Implementation of a robust motion control scheme for an Ostraciiform inspired underwater robot with caudal and pectoral fins

The productivity of the components is adversely affected by the poor surface integrity characteristics as a consequence of the generation of high temperature in the burnishing zone. The abundant use of conventional lubricants causes environmental pollution and health problems. To overcome these issues, cryogenic cooling has been used across the world to reduce the temperature generated in the burnishing zone. It is well known that most of the accidents which involve aero engines have revealed that the reason for this may be due to the failure of the first stage of compressor blades. Hence aerospace material, 17-4 precipitation hardenable (PH) stainless steel can be used in aero engines to minimize the failure occurring due to foreign object damage. In the present study, the effect of cryogenic diamond burnishing on the surface integrity characteristics such as surface roughness, surface hardness, surface morphology, surface topography, subsurface microhardness, and residual stress of 17-4 pH stainless steel have been investigated with a novel diamond burnishing tool and also it has been related to dry and minimum quantity lubrication (MQL) environments. From the experimental results of diamond burnishing process, surface roughness was observed to be reduced by 33%–50%, 34%–51% and 25%–40% in the cryogenic cooling environment in contrast with MQL and dry environments. Similarly, the surface hardness improvement in a cryogenic cooling environment was found to be 5%–7%, 6%–10%, and 6%–9%, in comparison with MQL and dry environments respectively. © 2019 The Society of Manufacturing Engineers

Journal of Manufacturing Processes

Effect of working parameters on the surface integrity in cryogenic diamond burnishing of 17-4 PH stainless steel with a novel diamond burnishing tool

Amajor sustainability concern of manufacturing industries is indiscriminate use of lubrication, energy consumption, and allied cost. To avoid such kind of situation and to improve the product quality, sustainable manufacturing concept has been widely used. One of the popular technique is the use of Minimum Quantity Lubrication (MQL) as a working fluid to improve the product performance. Diamond burnishing underMQLenvironment is an exceptional technique to obtain the improved surface integrity of the material without affecting operator health and environmental aspects. In this work, the impact of control factors on the surface integrity characteristics namely surface roughness, surface topography, surface hardness, surface morphology, residual stress and subsurface hardness of 17-4PHstainless steel have been studied underMQLenvironment by using a novel modified tool. It was ensured that minimum surface roughness of 0.05 μmand maximum surface hardness of 405HV had been achieved. Improved surface finish and surface hardness were obtained for a diamond sphere radius of 4mmand 3mmrespectively under optimal diamond burnishing conditions. The obtained investigational results confirm that a novel modified tool was successfully implemented to enhance the surface integrity characteristics under theMQLenvironment. © 2019 IOP Publishing Ltd.

Fulltext

Materials Research Express

Sustainable diamond burnishing of 17-4 PH stainless steel for enhanced surface integrity and product performance by using a novel modified tool

Conventional machining processes face several problems pertaining to the use of cutting fluids since most of them are toxic and contribute to a major portion of overhead costs. To address these issues, several methods like usage of solid lubricants, surface treatment, coating, minimum quantity lubrication and texturing of cutting tools have been adopted. Micro-texturing on cutting tool is a relatively recent technique which is being used to improve the tribological characteristics of the tool surface. Typical methods available for surface texturing are chemical etching, electro chemical machining, laser beam machining and electric discharge machining. Amongs these methods, there is a significant lack of literature exploring the feasibility of electric discharge machining (EDM) as a texturing process, especially on commonly used tool materials such as high-speed steel. This paper investigates the fabrication of micro-textures on high-speed steel to use micro-EDM. The EDM process parameters were optimized to create uniform textures. Upon comparing the performance of the textured cutting tools with conventional tools, it was found that the current texture geometry was highly effective in reducing the cutting forces at low speeds. © 2019, The Brazilian Society of Mechanical Sciences and Engineering.

Journal of the Brazilian Society of Mechanical Sciences and Engineering

Electric discharge texturing of HSS cutting tool and its performance in dry machining of aerospace alloy

The requirements of microfeature-based systems are essentially increasing due to their usage in every major field. Market needs microproducts with more functionality, information processing ability integrated together with compact size. Electro-discharge deposition process is an emerging nonlithographic, additive process to manufacture high aspect ratio 3D microfeatures. The current research work develops and investigates the application of magnetic field and shielding gas in the electro-discharge deposition process with experimental work and simulation model. Response surface methodology model is developed to perform parametric analysis and to ascertain the significance of introducing magnetic field and shielding gas in an electro-discharge deposition process. Results from atomic force microscope and optical image microscope shows that at higher magnetic field the deposition height increases with reduced width. From the EDAX compositional analysis, it is noted that the presence of shielding gas increases the percentage of copper composition and reduces the carbon and oxygen composition in the deposited material. The obtained results confirmed that the presence of magnetic field and shielding gas significantly improves the deposition process. © IMechE 2018.

Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science

Investigation of magnetic field and shielding gas in electro-discharge deposition process

The ability of proteins to sense and/or generate membrane curvature is crucial for many biological processes inside the cell. We introduce a model for the binding and unbinding of curvature inducing proteins on vesicles using Dynamic Triangulation Monte Carlo (DTMC) simulations. In our study, the interaction between membrane curvature and protein binding is characterised by the binding affinity parameter μ, which indicates the interaction strength. We demonstrate that both sensing and generation of curvature can be observed in the same system as a function of the protein binding affinity on the membrane. Our results show that at low μ values, proteins only sense membrane curvature, whereas at high μ values, they induce curvature. The transition between sensing and generation regimes is marked by a sharp change in the μ-dependence of the protein bound fraction. We present ways to quantitatively characterise these two regimes. We also observe that imposing tension on the membrane (through internal excess pressure for liposomes) extends the region of curvature sensing in the parameter space. © 2019 The Royal Society of Chemistry.

Soft Matter

Transition from curvature sensing to generation in a vesicle driven by protein binding strength and membrane tension

Purpose: The purpose of this paper is to numerically investigate the effect of various parameters such as density ratio, surface wettabilities and Weber number on the droplet dripping and detachment process. Design/methodology/approach: By using algebraic volume of fluid method, the governing equations are solved using a collocated finite volume approach in two-dimensions. Findings: The results indicate that, for small densities of droplet, it adheres to the surface except when the surface is hydrophobic, while an increase in Weber number or presence of an additional droplet in the vicinity led to detachment. Originality/value: The paper explores various characteristics of a droplet when two competing forces, namely, gravity and surface tension, act simultaneously. The detachment is observed for a given initial droplet size, as it becomes denser in an uniform gravitational field. The effect of droplet affinity for two droplets is also presented using the simulations. © 2018, Emerald Publishing Limited.