Chairul Imron

The effectiveness of passive control to reduce the drag coefficient

The drag coefficient of an object can be reduced by adding another smaller object placed in front of the main object, this has been done in previous research. In this paper, it will be added another smaller object and placed behind the main object in hopes will reduce the drag coefficient of the main object. The distance between the main object and the object in front is fixed, but with the object behind it has a varying distance. Reynolds numbers used were 100 and will be found the drag coefficient of the main objects are influenced by the distance of the object behind, so that the drag coefficient received by the main objek to be effective.

The effect of heat generation on mixed convection flow in nano fluids over a horizontal circular cylinder

The purpose of this research is to study the effect of heat generation on mixed convection flow on Nano fluids over a horizontal circular cylinder of a heated in two dimension form. A stream of fluids are steady and incompressible, a stream flowing vertically upwards for circular cylinder and the boundary layer at the stagnation point. Three different types of nanoparticles considered are Cu, Al2O3, and TiO2. Mixed convection flow in Nano fluids on the surface of a circular cylinder will cause the boundary layer. The governing boundary layer equations are transformed into a non-dimensional form, and then the non-dimensional forms are transformed into a similar boundary equations by using stream function. Furthermore, an implicit finite-difference scheme known as the Keller-box method is applied to solve numerically the resulting similar boundary layer equations. The result of the research by varying the non-dimensional parameters are mixed convection, Prandtl number, nanoparticle volume fraction, heat generation, and radius of a cylinder are as follows. First, the velocity profile increase and temperature profile decrease when mixed convection parameter increase. Second, the velocity and temperature profiles decrease when Prandtl number parameter increase. Third, the velocity profile with the variation of nanoparticle volume fraction (?) is increased when the value of ? is 0,1 ? ? ? 0,15 and the velocity profile decreases when the value of ? is 0,19 ? ? ? 0,5 while the temperature profile is increasing when the value of ? is 0,1 ? ? ? 0,5. Fourth, the velocity and temperature profiles increase when heat generation and the radius of the cylinder increase. The last, Cu, Al 2 O 3, and TiO 2 nanoparticles produce the same velocity and temperature profiles, but the three types of nanoparticles are different at the velocity and temperature values.

The Influence of distance between passive control and circular cylinder on wake

Two passive controls are placed in front of and behind the circular cylinder will reduce the coefficient of drag that is received by the circular cylinder. Passive control located in front of the circular cylinder has a fixed distance, while the passive control behind the circular cylinder has a varied distance. The drag coefficient of the circular cylinder depends on the distance between the circular cylinder and the passive control behind the circular cylinder, thus affecting the wake. In this paper, Reynolds numbers 100, 500 and 1000 will be used to find the wake.

Magnetohydrodynamics of unsteady viscous fluid on boundary layer past a sliced sphere

Magnetohydrodynamics (MHD) is important study in engineering and industrial fields. By study on MHD, we can reach the fluid flow characteristics that can be used to minimize its negative effect to an object. In decades, MHD has been widely studied in various geometry forms and fluid types. The sliced sphere is a geometry form that has not been investigated. In this paper we study magnetohydrodynamics of unsteady viscous fluid on boundary layer past a sliced sphere. Assumed that the fluid is incompressible, there is no magnetic field, there is no electrical voltage, the sliced sphere is fix and there is no barrier around the object. In this paper we focus on velocity profile at stagnation point (x = 0°). Mathematical model is governed by continuity and momentum equation. It is converted to non-dimensional, stream function, and similarity equation. Solution of the mathematical model is obtained by using Keller-Box numerical method. By giving various of slicing angle and various of magnetic parameter we get the simulation results. The simulation results show that increasing the slicing angle causes the velocity profile be steeper. Also, increasing the value of magnetic parameter causes the velocity profile be steeper. On the large slicing angle there is no significant effect of magnetic parameter to velocity profile, and on the high the value of magnetic parameter there is no significant effect of slicing angle to velocity profile.

Data Assimilation to Estimate the Water Level of River

Data assimilation is an estimation method for stochastic dynamic system by combining the mathematical model with measurement data. Water level and velocity of river are stochastic dynamic system, and it is important to estimate the water level and velocity of river flow to reduce flood risk disaster. Here, we estimate the water level and velocity of river flow by using data assimilation specially Kalman filter and Ensemble Kalman filter. We define mathematical model of river flow, discretize and do simulation by Kalman filter and Ensemble Kalman filter. In data assimilation, we forecast the water level and velocity by using mathematical model and based on the measurement data, the correction of forecasting is made.

The distance between the cylinder affect the cylinder pressure

Trimaran is a vessel with a hull that is associated with the three bridge structures. Assuming that the elliptical cylinder-shaped hull, trimaran built by three elliptical cylinder with side-by-side configuration. The distance between the ellipse varies will determine the pressure received by the ellipse in the center. This problem is solved using the Navier-Stokes equations and solved by the finite difference. Results from this study is the lowest pressure received by elliptical midddle.