• SUSHIL KUMAR

      Articles written in Sadhana

    • Thermal effect on gravity waves in a compressible liquid layer over a solid half-space under initial hydrostatic stress

      Sushil Kumar Addy Nil Ratan Chakraborty

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      This paper deals with the effect of temperature on gravity waves in a compressible liquid layer over a solid half-space. It has been assumed that the liquid layer is under the action of gravity, while the solid half-space is under the influence of initial compressive hydrostatic stress. When the temperature of the half-space is altered, gravity waves propagate through the liquid layer along with sub-oceanic Rayleigh waves in the system. A new frequency equation has been derived here for gravity waves and sub-oceanic Rayleigh waves.

      It has been shown graphically that the phase velocity of gravity waves is influenced significantly by the initial compressive hydrostatic stress present in the solid half-space, for a particular value of the phase velocity of sub-oceanic Rayleigh waves and different coupling co-efficients of the temperature.

    • An analytical investigation of pressure-driven flow and heat transfer of a Sisko fluid flowing through parallel plates with viscous dissipation

      SUMANTA CHAUDHURI SUSHIL KUMAR RATHORE

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      Pressure driven flow of a Sisko fluid through rectangular parallel plates, having different wall temperatures is investigated considering the effect of viscous dissipation. The nonlinear momentum and energy conservation equations are solved employing homotopy perturbation method (HPM) and analytical solutions for the velocity, flow rate and temperature distributions are obtained. The analytical solution of pressure-driven flow and heat transfer characteristics of Sisko fluids flowing through parallel plates, taking into account viscousdissipation effect, has not been addressed earlier. For a special case of a typical Sisko fluid, the HPM solution exhibits an excellent agreement with the exact solution. Effects of various parameters such as Sisko fluid parameter, non-Newtonian index and Brinkman numbers on the variation of velocity and temperature are discussed. Further, temperature distribution in flow of Sisko fluids through parallel plates with both the plates maintained at same temperature is also obtained by a suitable substitution in the expression for temperaturedistribution. It is observed that the velocity decreases significantly with an increase in Sisko fluid parameter. Temperature of the fluid decreases with an increase in Sisko fluid parameter and displays an increasing trend with an increase in Brinkman number. Results of the present study are useful for designing thermal systems handling polymer flows. For the typical case of two plates having same temperature, the maximum temperature is observed to occur at the centre, which is attributed to the effect of viscous dissipation acting as an internal source. The theoretical framework developed and analytical solution provided for the problem under consideration may be taken as benchmark result for validation of future work

    • On the distribution-free continuous-review production-inventory model with service level constraint

      SUSHIL KUMAR BHUIYA DEBJANI CHAKRABORTY

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      In this article, we study a continuous-review production-inventory model that assembles lost sales and backorders with service level constraint. The study under consideration assumes that the distribution of demand during the lead-time is known partially. The objective of this paper is twofold. Firstly, the distributionfree procedure is applied to obtain a closed-form solution of optimal production quantity, re-order level and lead-time in the random framework. Secondly, considering demand as a fuzzy random variable, the procedure isextended to the fuzzy random framework in which an algorithm is proposed to find the optimal global solution. Two numerical examples are provided to illustrate the methods. Furthermore, sensitivity analysis is performed to present some managerial inferences

    • Experimental investigation of magnetic-field-assisted electric discharge machining by silicon-based dielectric of Inconel 706 superalloy

      SUSHIL KUMAR MUDIMALLANA GOUD NARENDRA MOHAN SURI

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      Inconel 706 is a nickel–iron-based superalloy having higher mechanical strength along with easiness of fabrication, which makes it suitable for gas turbine disk applications. The current study investigates the hybrid magnetic-field-assisted powder mixed electric discharge machining (MFAPMEDM) process to improveperformance in machining Inconel 706. For conducting experiments, an in-house set-up was designed and fabricated. Experiments were conducted according to the Taguchi L9 OA and ANOVA to examine the effect of the peak current (Ip) and pulse duration (P-on/P-off) on the material removal rate (MRR) and surface roughness (Ra) of the machined samples. The quality of the machined surface is assessed using a field emission scanning electron microscope (FESEM), which has revealed the presence of micro-holes, melted debris and microglobuleson the machined specimen surface. The Ra is significantly affected by Ip (49.63%) and P-off (37.12%).Further, Ip has more than 78% contribution to the MRR. Furthermore, a mathematical model has been established to develop the relation between input and output factors

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