Finite Difference Numerical Method: Applications in Lightning Electromagnetic Pulse and Heat Diffusion

The finite difference time domain (FDTD) is a technique of the finite difference numerical method and is a simple but powerful and versatile tool that has been widely applied in many scientific and engineering problems. A typical application of the technique is in dealing with electromagnetic (EM) wave interactions with physical structures. This technique has been used to solve governing equations of various systems through obtaining numerical approximations to the time-dependent differential equations for computer simulations. This paper demonstrates the accuracy and versatility of the application of FDTD method by applying it to examine the effect of lightning electromagnetic pulse (LEMP) on a transmission line using a cross-linked polyethylene (XLPE) insulated power cable, as well as to analyze heat diffusion in a microchip heat sink made from Aluminium Alloy 6061. The effect of LEMP on a transmission line showed that the higher the values of the line parameters, the larger the voltages that will be induced on the line and that bigger values of finite difference (FD) parameters give a more accurate model subject to a stability criterion. Accurate modelling of induced voltages ensures that appropriate mitigating techniques can be deployed to reduce or eliminate the damaging effect of these on electrical and/or electronic devices/systems. Similarly, proper modeling of a heat sink provides the ability to closely estimate heat diffusion at product design stage such that a design is confirmed as workable before manufacture; thereby saving cost. Keywords—Finite Difference Method, Finite Difference Time Domain, Engineering Applications, Lightning Electromagnetic Pulse, Heat Diffusion.

Magnetohydrodynamics Free Convection Flow of Incompressible Fluids over Corrugated Vibrating Bottom Surface with Hall Currents and Heat and Mass Transfers

Magnetohydrodynamics free convection flow of incompressible fluids over corrugated vibrating bottom surface with Hall currents and heat and mass transfers considering heat flux is discussed. The corrugation patterns suggested are sinusoidal in nature. The governing equations are solved by the explicit finite difference numerical method of the forward-time backward-space scheme to obtain the analytical results for velocity, concentration, and temperature profiles. The unsteady resultant velocities, concentration, and temperature for various values of physical parameters are discussed in detail, and it is shown that they have significant effects on the fluid flow, and heat and mass transfers are shown graphically.

Thermal Analysis In Optical Waveguides

Analisis haba di dalam struktur pandu gelombang optik telah dijalankan untuk mengkaji taburan suhu keratan rentas apabila dipanaskan dengan elemen pemanas. Persamaan umum haba diprogramkan menggunakan kaedah berangka pembezaan terhingga. Perbezaan keputusan yang ketara telah diperoleh apabila nilai keberaliran haba yang berbeza bagi setiap elemen pandu gelombang dan mekanisma konveksi ke persekitaran dipertimbangkan. Kata kunci: Kesan termo–optik, analisis terma, kaedah pembezaan terhingga A thermal analysis in optical waveguides structure is simulated in order to predict the temperature distribution over the waveguide cross–section, when heated by a heating element. A steady state heat equation is solved by using finite difference numerical method. It is observed that by applying different value of thermal conductivities for each waveguide element and further application of convection mechanism to the ambient, obvious differences with other researchers’ work are recorded. Key words: Thermo–optic effect, thermal analysis, finite difference method

Natural Convection from a Horizontal Cylinder—Laminar Regime

A finite-difference numerical method has been adopted to generate flow patterns and heat transfer characteristics for laminar, steady-state, two-dimensional natural convection around a circular cylinder submerged in an unbounded Boussinesq fluid. The approach allows the use of nonuniform as well as uniform specified temperature and heat flux distributions over the cylindrical surface. Part of the results are generated for reverse convective flows with recirculation zones which occur when part of the cylinder is below the ambient temperature while the remaining part is above. The results for uniform temperature boundary condition are in good agreement with the experimental data and other solutions available in literature.