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Journal : international journal of computing science and applied mathematics-ijcsam

Numerical Simulation of Fluid Flow Around Circular Cylinder and Three Passive Controls to Reduce Drag Coefficient at Re=500 Chairul Imron; Amirul Hakam; Basuki Widodo; Tri Yogi Yuwono
(IJCSAM) International Journal of Computing Science and Applied Mathematics Vol. 6 No. 1 (2020)
Publisher : LPPM Institut Teknologi Sepuluh Nopember

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Abstract

Numerical experiments and simulations of fluid flow through the outer surface of a circular cylinder and three passive controls have been investigated to determine the proper configuration of three passive controls in reducing the drag coefficient. One of passive controls is placed in front of the cylinder with distance ratio (S:D) = 2:4 and the other two passive controls are placed behind the cylinder with distance ratio (T:D) = 1:6;1:8. The angle between two passive controls behind the cylinder are a =30 deg;60 deg;90 deg;120 deg. The Navier-Stokes equations for incompressible, viscous and unsteady fluid flows is solved based on SIMPLE (Semi-Implicit for Pressure-Linked Equations) algorithms and discretized using finite-difference method. The difference in a affects the reduction in the drag coefficient significantly. The best configuration of three passive controls design is one of passive controls put at the distance ratio S=D = 2:4;T=D = 1:6 and a = 60. This configuration can reduce the drag coefficient optimally to 21.2109%.
Mathematical Model of Free Convection Boundary Layer Flow on Solid Sphere with Viscous Dissipation and Thermal Radiation Muhammad Khairul Anuar Mohamed; Mohd Zuki Salleh; Abid Hussanan; Norhafizah Md Sarif; Nor Aida Zuraimi Md Noar; Anuar Ishak; Basuki Widodo
(IJCSAM) International Journal of Computing Science and Applied Mathematics Vol. 2 No. 2 (2016)
Publisher : LPPM Institut Teknologi Sepuluh Nopember

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Abstract

Present study considers the mathematical modeling of free convection boundary layer flow and heat transfer on a solid sphere with viscous dissipation and thermal radiation effects. The transformed partial differential equations are solved numerically by using the Keller-box method. Numerical solutions are obtained for the reduced Nusselt number, the local skin friction coefficient, the velocity and temperature profiles. The features of the flow characteristics for various values of the Prandtl number, radiation parameter and Eckert number are discussed. It is worth mentioning that the results are obtained until x = 180 degree. This is contrary to the previous report where the separation boundary layer flow occurs after x = 120 degree. The results in this paper is important for the researchers working in the area of boundary layer flow and this can be used as reference and also as complement for comparison purposes in the future.
Optimal Control of the Spread of Dengue Fever by Controlling the Vectors Growth Affected by Climate Change and Treatment Basuki Widodo; Nur Asiyah; Aulia Rahma; Kamiran Kamiran; Chairul Imron
(IJCSAM) International Journal of Computing Science and Applied Mathematics Vol. 10 No. 2 (2024)
Publisher : LPPM Institut Teknologi Sepuluh Nopember

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.12962/j24775401.ijcsam.v10i2.4586

Abstract

Dengue Hemorrhagic Fever (DHF) is an infectious disease caused by the dengue virus and is spread through the bite of an adult female Aedes aegypti mosquito, as a vector (disease-carrying animal), to humans. This disease is still a major health problem in tropical and subtropical regions. Indonesia is reported as the 2nd highest country among 30 other endemic countries. Warm temperatures during the rainy season are ideal conditions for mosquitoes to lay eggs optimally, increasing egg maturity, and shortening the virus incubation period. This has an impact on increasing the number of mosquitoes and the risk of disease transmission. In this study, control of DHF was carried out by controlling the growth of vectors in the egg and adult phases of mosquitoes, which were influenced by rainfall and air temperature, as well as the treatment of infected humans. Before carrying out the control, stability analysis around the equilibrium point is first conducted. Next, the numerical solution is obtained using the Runge-Kutta method of order 4 with the help of MATLAB software. The results of the analysis show that, based on the optimal control effect in the form of mosquito egg death (k1), adult mosquito death (k2), and human treatment (k3), in the cities of Pekanbaru and Solok, there is not much difference between the two. However, there is a slight difference in the increase in the human population that is susceptible to disease.
Numerical Study of Vortex Shedding Control Using Viscoelastic Flow Over an Elliptical Cylinder Annisa Dwi Sulistyaningtyas; Basuki Widodo; Chairul Imron; Hanim Faizah
(IJCSAM) International Journal of Computing Science and Applied Mathematics Vol. 12 No. 1 (2026)
Publisher : LPPM Institut Teknologi Sepuluh Nopember

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.12962/j24775401.ijcsam.v12i1.9065

Abstract

Vortex-Induced Vibration (VIV) mitigation is a critical issue in engineering systems involving bluff bodies subjected to fluid flow. This study presents a numerical investigation of viscoelastic fluid flow over an elliptical cylinder as a passive control strategy to suppress vortex shedding. The governing continuity, momentum, and energy equations for an incompressible viscoelastic fluid are formulated and solved using an implicit finite difference method. The viscoelastic behavior of the fluid is incorporated through a nonlinear constitutive model, and the resulting system of equations is transformed into a dimensionless form to facilitate analysis. The study focuses on the effects of key parameters, including the viscoelastic parameter K, the Prandtl number P r, and the geometric aspect ratio a/b of the elliptical cylinder. Numerical simulations are performed using MATLAB to evaluate the resulting velocity and temperature distributions within the boundary layer region. The results indicate that increasing the viscoelastic parameter significantly reduces the peak velocity near the wall and weakens the velocity gradient, leading to a decrease in shear stress. In addition, higher viscoelasticity contributes to a thicker momentum and thermal boundary layer, which reduces the rate of heat transfer from the surface. Furthermore, variations in the Prandtl number and aspect ratio are found to influence the localization of thermal and momentum transport. Higher values of P r result in thinner thermal boundary layers and enhanced temperature gradients near the surface, while changes in a/b primarily affect the near-wall flow structure. Overall, the combined effects of viscoelasticity and geometric modification demonstrate a strong potential for attenuating vortex shedding and reducing the likelihood and intensity of VIV. These findings provide valuable insights for the design of engineering systems involving non-Newtonian fluids and flow-induced vibrations.