Yazar "Ahmad, Hijaz" seçeneğine göre listele

Listeleniyor 1 - 8 / 8
  • [ X ]
    Öğe
    A novel method for nonlinear singular oscillators
    (Sage Publications Ltd, 2021) Akgul, Ali; Ahmad, Hijaz; Chu, Yu-Ming; Thounthong, Phatiphat
    The present work deals with a study of a nonlinear singular oscillator. To approximate the frequency-amplitude relationship of the singular oscillator, reproducing kernel method is employed. The approximate solution is compared with the exact solution as well as the results obtained by the He's frequency-amplitude formulation, to show the effectiveness of the proposed technique for solving the problem.
  • [ X ]
    Öğe
    Modeling and analysis of fractional order Zika model
    (Amer Inst Mathematical Sciences-Aims, 2022) Farman, Muhammad; Akgul, Ali; Askar, Sameh; Botmart, Thongchai; Ahmad, Aqeel; Ahmad, Hijaz
    We propose mathematical model for the transmission of the Zika virus for humans spread by mosquitoes. We construct a scheme for the Zika virus model with Atangna-Baleanue Caputo sense and fractal fractional operator by using generalized Mittag-Leffler kernel. The positivity and boundedness of the model are also calculated. The existence of uniquene solution is derived and stability analysis has been made for the model by using the fixed point theory. Numerical simulations are made by using the Atangana-Toufik scheme and fractal fractional operator with a different dimension of fractional values which support the theoretical outcome of the proposed system. Developed scheme including simulation will provide better understanding in future analysis and for control strategy regarding Zika virus.
  • [ X ]
    Öğe
    New Perspective on the Conventional Solutions of the Nonlinear Time-Fractional Partial Differential Equations
    (Wiley-Hindawi, 2020) Ahmad, Hijaz; Akgul, Ali; Khan, Tufail A.; Stanimirovic, Predrag S.; Chu, Yu-Ming
    The role of integer and noninteger order partial differential equations (PDE) is essential in applied sciences and engineering. Exact solutions of these equations are sometimes difficult to find. Therefore, it takes time to develop some numerical techniques to find accurate numerical solutions of these types of differential equations. This work aims to present a novel approach termed as fractional iteration algorithm-I for finding the numerical solution of nonlinear noninteger order partial differential equations. The proposed approach is developed and tested on nonlinear fractional-order Fornberg-Whitham equation and employed without using any transformation, Adomian polynomials, small perturbation, discretization, or linearization. The fractional derivatives are taken in the Caputo sense. To assess the efficiency and precision of the suggested method, the tabulated numerical results are compared with the standard variational iteration method and the exact solution as well. In addition, numerical results for different cases of the fractional-order alpha are presented graphically, which show the effectiveness of the proposed procedure and revealed that the proposed scheme is very effective, suitable for fractional PDEs, and may be viewed as a generalization of the existing methods for solving integer and noninteger order differential equations.
  • [ X ]
    Öğe
    Numerical Analysis of Natural Convection Driven Flow of a Non-Newtonian Power-Law Fluid in a Trapezoidal Enclosure with a U-Shaped Constructal
    (Mdpi, 2021) Bilal, Sardar; Rehman, Maryam; Noeiaghdam, Samad; Ahmad, Hijaz; Akgul, Ali
    Placement of fins in enclosures has promising utilization in advanced technological processes due to their role as heat reducing/generating elements such as in conventional furnaces, economizers, gas turbines, heat exchangers, superconductive heaters and so forth. The advancement in technologies in power engineering and microelectronics requires the development of effective cooling systems. This evolution involves the utilization of fins of significantly variable geometries enclosed in cavities to increase the heat elimination from heat-generating mechanisms. Since fins are considered to play an effective role in the escalation of heat transmission, the current study is conducted to examine the transfer of heat in cavities embedding fins, as well as the effect of a range of several parameters upon the transmission of energy. The following research is supplemented with the interpretation of the thermo-physical aspects of a power-law liquid enclosed in a trapezoidal cavity embedding a U-shaped fin. The Boussinesq approximation is utilized to generate the mathematical attributes of factors describing natural convection, which are then used in the momentum equation. Furthermore, the Fourier law is applied to formulate the streaming heat inside the fluid flow region. The formulated system describing the problem is non-dimensionalized using similarity transformations. The geometry of the problem comprises a trapezoidal cavity with a non-uniformly heated U-shaped fin introduced at the center of the base of the enclosure. The boundaries of the cavity are at no-slip conditions. Non-uniform heating is provided at the walls (l(1) and l(2)), curves (c(1),c(2) and c(3)) and surfaces (s(1) and s(2)) of the fin; the upper wall is insulated whereas the base and sidewalls of the enclosure are kept cold. The solution of the non-dimensionalized equations is procured by the Galerkin finite element procedure. To acquire information regarding the change in displacement w.r.t time and temperature, supplementary quadratic interpolating functions are also observed. An amalgam meshing is constructed to elaborate the triangular and quadrilateral elements of the trapezoidal domain. Observation of significant variation in the flow configurations for a specified range of parameters is taken into consideration i.e., 0.5 <= n <= 1.5 and 10(4)<= Ra <= 10(6). Furthermore, flow structures in the form of velocity profiles, streamlines, and temperature contours are interpreted for the parameters taken into account. It is deduced from the study that ascending magnitude of (Ra) elevates level of kinetic energy and magnitude of heat flux; however, a contrary configuration is encapsulated for the power-law index. Navier-Stokes equations constituting the phenomenon are written with the help of non-dimensionalized stream function, temperature profiles, and vortices, and the solutions are acquired using the finite element method. Furthermore, the attained outcomes are accessible through velocity and temperature profiles. It is worth highlighting the fact that the following analysis enumerates the pseudo-plastic, viscous and dilatant behavior of the fluid for different values of (n). This study highlights that the momentum profile and the heat transportation increase by increasing (Ra) and decline as the viscosity of the fluid increases. Overall, it can be seen from the current study that heat transportation increases with the insertion of a fin in the cavity. The current communication signifies the phenomenon of a power-law fluid flow filling a trapezoidal cavity enclosing a U-shaped fin. Previously, researchers have studied such phenomena mostly in Newtonian fluids, hence the present effort presents novelty regarding consideration of a power-law liquid in a trapezoidal enclosure by the placement of a U-shaped fin.
  • [ X ]
    Öğe
    NUMERICAL INVESTIGATION OF THE INTERACTION BETWEEN THE ROUGHNESS AND THE TRIANGULAR OBSTRUCTIONS IN A RECTANGULAR CHANNEL
    (Vinca Inst Nuclear Sci, 2023) Sari Hassoun, Zakaria; Aliane, Khaled; Akgul, Ali; Jarrar, Rabab; Asad, Jihad; Menni, Younes; Ahmad, Hijaz
    The study is conducted around a heat exchanger, its channel is horizontal rect-angular, its upper wall is isothermal, while its lower wall is thermally insulated, containing extended surfaces in the form of triangular obstacles attached in a stag-gered manner periodically. Four models of the channel with various roughnesses were compared in this study. Square, triangular Type 1, triangular Type 2, and triangular Type 3 roughnesses, which are positioned on the hot top part of the channel (absorber), downstream of the last obstacle, are examined to promote heat transfer between the absorber and the heat transfer fluid. The case of triangular roughness (Type 3) is the optimal case in terms of improved heat transfer. More-over, it shows a significant decrease in terms of friction values.
  • [ X ]
    Öğe
    Numerical solution of time-fractional coupled Korteweg-de Vries and Klein-Gordon equations by local meshless method
    (Indian Acad Sciences, 2021) Khan, Muhammad Nawaz; Ahmad, Imtiaz; Akgul, Ali; Ahmad, Hijaz; Thounthong, Phatiphat
    This article provides numerical simulations of the time-fractional coupled Korteweg-de Vries and Klein-Gordon equations via the local meshless collocation method (LMCM) utilising the radial basis functions. The recommended local meshless technique is utilised for the space derivatives of the models whereas Caputo fractional definition is used for time-fractional derivative. Numerical experiments are performed for one-dimensional coupled Korteweg-de Vries and two-dimensional Klein-Gordon equations. In order to verify the efficiency and accuracy of the proposed meshless method, numerical results are compared with exact and numerical techniques reported in recent literature which reveals that the method is computationally attractive and produces better results.
  • [ X ]
    Öğe
    Reproducing kernel method for Fangzhu's oscillator for water collection from air
    (Wiley, 2020) Akgul, Ali; Ahmad, Hijaz
    In this article, reproducing kernel method is used to approximate nonlinear oscillator in order to reveal main factors affecting the usefulness of an ancient water collection device known as Fangzhu, that is, the surface temperature, the air velocity, surface structure, and suitable super-hydrophilic and super-hydrophobic surface duals. The approximate solution is compared with the exact solution as well as the results obtained by the simplest frequency-amplitude formulation, to show the effectiveness of the proposed technique for solving this type nonlinear oscillator. Fangzhu plays a significant role in ocean engineering, modern architecture, self-lubrication of moving surfaces, transportation, and many others to catch water from air for day-to-day use.
  • [ X ]
    Öğe
    TURBULENT FLOWS AROUND RECTANGULAR AND TRIANGULAR TURBULATORS IN BAFFLED CHANNELS A Computational Analysis
    (Vinca Inst Nuclear Sci, 2022) Salmi, Mohamed; Afif, Benameur; Akgul, Ali; Jarrar, Rabab; Shanak, Hussein; Menni, Younes; Ahmad, Hijaz
    The present paper highlights a computational analysis of air-flows around rectangular and triangular turbulators inside baffled heat exchanger channels in order to improve heat transfer between the fluid and their heated areas. The dynamic and thermal fields as well as fluid temperature curves at the outlet of the exchanger are studied. The computational study is conducted by utilizing SIMPLE algorithm with FLUENT system based on the finite volumes. The analysis clearly demonstrated the presence of highly turbulent flows and the appearance of many vortices in various regions of the exchanger. By comparing the different heat exchangers, it was found that the baffled channel fitted with rectangular turbulators produced high fluid temperature values at the channel outlet, indicating the significance of using this rectangular form of turbulators in order to enhance the interaction between the hot spaces and the used fluid.