Authors:Asif Khan, Shahab Khushnood, Najum Ul Saqib, Imran Sajid Shahid Pages: 77 - 91 Abstract: It is sound recognized that when the tube is forced to vibrate or is naturally excited to sufficient amplitudes by flow-induced forces, cyclones peeling phenomena arises at downstream of a tube which clues to vibration in the tube. Two-dimensional numerical recreation model for the computation of flow induced vibration of heat exchanger tube bundle imperiled to cross- flow is proficient in current research. Computational Fluid Dynamics (CFD) tool, GAMBIT (grid generation) and ANSYS FLUENT (fluid flow analysis) are operated during numerical investigations. k-epsilon model is used to solve the Navier– Stokes equations. Lift coefficient graph derived from analysis is used to predict the vortex shedding frequency using Fast Fourier Transform (FFT). The results of flow rate, Strouhal number, Reduced velocity, Natural frequency of tube as found from the experimental data has been verified numerically for a Reynolds number range of 4.45 × 104<Re <4.65 × 104 . It is concluded that experimental results are well in agreement with the numerical results. PubDate: 2017-12-28 DOI: 10.3329/jname.v14i2.25894 Issue No:Vol. 14, No. 2 (2017)
Authors:A.B.M. Mainul Bari, Saeed Rubaiee, Anas Ahmed, AKM Masud Pages: 93 - 100 Abstract: In modern days silicon is being extensively used in making electronic semiconductor-based chips and IC’s. In this research, the change in different thermodynamic properties of silicon like lattice heat capacity, molar enthalpy and Debye temperature at constant pressure, with the change in temperature, has been investigated by using molecular dynamics (MD) simulation method. Knowing silicon’ thermodynamic functions are quite important, because many electronic companies are nowadays trying a lot to reduce the heat generated by their semiconductor chips as excessive heating of the chip not only warms up the device quickly but also reduces the chip life. The results obtained from this simulation help engineers to design electronic chips more efficiently. For simulation “Accelrys Materials Studio” (Version 5.0) software has been used. The simulation was run for silicon FCC diamond structured cell. The analysis tool used in the simulation is known as CASTEP (Cambridge Sequential Total Energy Package). This tool is specialized for performing molecular level thermodynamic analysis to generate data and graphs for the change in different temperature dependent properties of the molecular system. The interaction between silicon atoms was expressed by the Kohn-Sham potential and MD calculation was conducted on crystalline state of silicon at temperatures between 0 and 1000 K. Here, density function theory (DFT) based tool has been used to derive density of state relations. Results obtained by the simulation were compared with published experimental values and it was found that the simulation results were close to the experimental values. PubDate: 2017-12-28 DOI: 10.3329/jname.v14i2.30128 Issue No:Vol. 14, No. 2 (2017)
Authors:P. Sharma, R. Saboo Pages: 101 - 114 Abstract: This paper deals with unsteady oscillatory flow of viscous incompressible fluid with heat & mass transfer in a horizontal channel partially occupied by porous medium following the Darcy-Brinkman model. The interior territory of the channel consists of two regions; one of them is filled with porous material and second is clear fluid. At the porous medium fluid interface, interfacial coupling conditions for the fluid velocity, temperature and concentration were used to derive the analytical solution. The effects of pertinent physical fluid parameter like porosity, viscosity ratio, density ratio etc. on velocity, temperature and concentration distribution are considered and demonstrated through graphs. Also, the non-dimensional Skin-friction coefficient, Nusselt number and Sherwood number have been calculated and reported in tabular form. PubDate: 2017-12-28 DOI: 10.3329/jname.v14i2.25584 Issue No:Vol. 14, No. 2 (2017)
Authors:Anoop I. Shirkol, Nasar Thuvanismail Pages: 115 - 133 Abstract: Wave interaction with a floating thin elastic plate which can be used as floating platform is analyzed using Boundary Element Method (BEM) for different shapes such as rectangular, circular and triangular. Different support conditions are considered and the performance of the floating platform under the action of ocean waves is explored. The study is performed under the assumption of linearized water wave theory and the floating elastic plate is modelled based on the Euler-Bernoulli beam theory. Using Galerkin’s approach, a numerical model has been developed and the hydrodynamic loading on the floating elastic plate of shallow draft (thickness) is investigated. The wave forces are generated by the numerical model for the analysis of the floating plate. The resulting bending moment and optimal deflection due to encountering wave force is analysed. The present study will be helpful in design and analysis of the large floating platform in ocean waves. PubDate: 2017-12-28 DOI: 10.3329/jname.v14i2.28267 Issue No:Vol. 14, No. 2 (2017)
Authors:M. Ali, M. A. Alim, R. Nasrin, M. S. Alam Pages: 135 - 144 Abstract: In this work, the effects of dimensionless parameters on the velocity field, thermal field and nanoparticle concentration have been analyzed. In this respect, the magnetohydrodynamic (MHD) boundary layer nanofluid flow along a moving wedge is considered. Therefore, a similarity solution has been derived like Falkner – Skan solution and identified the point of inflexion. So the governing partial differential equations transform into ordinary differential equations by using the similarity transformation. These ordinary differential equations are numerically solved using fourth order Runge–Kutta method along with shooting technique. The present results have been shown graphically and in tabular form. From the graph, the results indicate that the velocity increases with increasing values of pressure gradient, magnetic induction and velocity ratio. The temperature decreases for velocity ratio, Brownian motion and Prandtl number but opposite result arises for increasing values of thermophoresis. The nanoparticle concentration decreases with an increase in pressure gradient, Brownian motion and Lewis number, but increases for thermophoresis. Besides, the solution of nanoparticle concentration exists in the case of Brownian motion is less than 0.2, thermophoresis is less than 0.14 and lewis number is greater than 1.0. Finally, for validity and accuracy the present results have been compared with previous work and found to be in good agreement. PubDate: 2017-12-28 DOI: 10.3329/jname.v14i2.30633 Issue No:Vol. 14, No. 2 (2017)
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