Department of Mechanical engineering

Permanent URI for this collectionhttp://localhost:4000/handle/123456789/1921

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Subject: search.filters.subject.Finite element method

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    Magnetohydrodynamic ferrofluid flow and entropy generation in a trapezoidal thermal system with a half-elliptical heater
    (Springer, 2025-10) Bhattacharyya, Suvanjan
    This study numerically investigates magnetohydrodynamic (MHD) nanofluid flow and entropy production in a trapezoidal-shaped thermal system with a centrally positioned half-elliptical heater. Fe3O4/water nanofluid is utilized as the carrier medium with the system subjected to a uniform magnetizing field. The evolved transport equations are solved numerically adopting the finite element method, with results illustrated through streamlines, isotherms, energy flux vectors, and entropy generation contours. The effects of key variables including Rayleigh number (103 ≤ Ra ≤ 106), Hartmann number (0 ≤ Ha ≤ 100), and orientation of the magnetic field (0° ≤ γ ≤ 180°) are systematically analyzed. From the results, it is observed that increasing Ra augments heat transfer and flow strength, while higher Ha values suppress convection. Magnetic field orientation meaningfully influences hydrothermal flow patterns and thermal transport dynamics. The trapezoidal geometry consistently outperforms square and inverted trapezoidal configurations in terms of heat transfer efficiency. Entropy generation analysis shows that thermal entropy production dictates the viscous as well as magnetic irreversibilities. The results of this study offer important comprehensions for enhancing thermal management in MHD nanofluidic thermal systems with intricate geometries. Similar content being viewed by others
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    Experimental characterization and finite element modeling of through thickness deformation gradient in a cold rolled zirconium sheet
    (Elsevier, 2017-11) Kumar, Gulshan
    A commercial Zirconium alloy was subjected to different thickness reductions (20%, 40% and 60%) by cold rolling. A through-thickness gradient in microstructure, crystallographic texture and residual stress was observed. This gradient was till 1/8th of the specimen thickness, and implied a corresponding anisotropy in the imposed strain state. An elasto-plastic FE (finite element) model was developed to capture such through thickness deformation gradients. A reasonably good agreement was observed between the experimental and predicted residual stress distributions when the material anisotropy was accounted for. Through-thickness residual stress evolution was shown to be significantly affected by material anisotropy and to a lesser extent by the rolling parameters (coefficient of friction and rotational speed).
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    The effects of longitudinal heat conduction in compact plate-fin and tube-fin heat exchangers using a finite element method
    (Elsevier, 1997-04) Ranganayakulu, Chennu
    An analysis of the crossflow plate-fin, crossflow tube-fin, counterflow plate-fin and parallel flow plate-fin compact heat exchangers accounting for the effect of ‘longitudinal heat conduction’ through the exchanger wall is carried out using a finite element method. The exchanger effectiveness and its deterioration due to the longitudinal heat conduction effect have been calculated for various designs and operating conditions of the exchanger. The results indicate that the thermal performance deterioration of crossflow plate-fin, crossflow tube-fin and counterflow plate-fin heat exchangers due to longitudinal heat conduction may become significant especially when the fluid capacity rate ratio is equal to one and when the longitudinal heat conduction parameter is large.
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    Slip hydrodynamics of combined electroosmotic and pressure driven flows of power law fluids through narrow confinements
    (Elsevier, 2021-10) Harikrishnan, A.R.
    Electroosmotic flows (EOF) in microfluidic devices can be greatly enhanced over superhydrophobic surfaces because the high shear rates within the electrical double layer can drive large slip velocities at the interface. Using the power law fluid model, we derive a novel formulation for the Helmholtz–Smoluchowski (HS) velocity and use it to examine the effect of slip on the hydrodynamics of a coupled pressure driven and EOF. Semi analytical relations for the velocity gradient are obtained for cases of a favourable pressure gradient but exact solutions of the velocity can be found only for certain power law indices. Cases of adverse pressure gradient and fractional power law indices are investigated using numerically using the Galerkin Finite Element Method. The validity of the semi analytical relations verified by comparison with the numerical method. The presence of velocity slip at the wall leads to an enhancement of the HS velocity that is most pronounced in shear thinning fluids. Adverse pressure gradients are observed to generate an inflection in the velocity profile and even a two-way flow for certain flow parameters. The strength of the adverse pressure gradient needed to setup a reverse flow at the channel centre reduces as the slip length is increased. The location of the point of inflection is found to depend on the channel height, pressure gradient, electric field, slip length, Debye length and non-Newtonian behaviour.
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    Model based fault diagnosis in rotating machinery
    (International Journal of Performability Engineering, 2011-11) Jalan, Arun Kumar
    A continuing task in engineering is to increase the reliability, availability and safety of technical processes and to achieve these fault diagnosis becomes an advanced supervision tool in the present industries. Vibration in rotating machinery is mostly caused by unbalance, misalignment, shaft crack, mechanical looseness and other malfunctions. The objective of this paper is to propose a model based scheme for fault diagnosis of a rotor system. Presence of faults changes the dynamic behaviour of the system which is taken into account by equivalent loads acting on the healthy system model. In order to diagnose the faults in a rotor system the experimental time responses for healthy system as well as for faulty system were used. It was observed that the proposed scheme successfully detects and identifies the type, location and amount of fault in a rotor system for unbalance, misalignment and crack. This method has thus demonstrated the efficacy of the model based fault detection system for a simple rotor-bearing system.