Basuki Widodo

Experimental and numerical study of the resistance component interactions of catamarans

The paper presents the results of experimental and numerical investigations into the calm water resistance characteristics of slender catamarans and the interference effects of hull separation. The model hull forms comprise modern symmetrical catamaran hulls with lateral separation. A series of tests were conducted in a towing tank with lateral separation of the hulls of Sc/L = 0.2 – 0.4 and speeds corresponding to Froude number up to 0.65. Tests were carried out in a low speed wind tunnel to determine viscous interference effects between the hulls. Numerical computational fluid dynamics modelling was also used to estimate interference effects on the resistance components. It was found that the experimental and numerical investigations were in excellent agreement and provide satisfactory estimates of the resistance components. Results in the paper offer some practical data and further insight into wave and viscous interference effects.

Performance enhancement of inverted pendulum system by using type 2 fuzzy sliding mode control (T2FSMC)

The drawbacks of using FSMC when controlling the position motion on a non linear inverted pendulum system are the chattering problem and the robustness against parameter uncertainty and disturbances. This paper consider about the implementation of Fuzzy Type 2 in combining with SMC (T2FSMC) to enhance the ability of FSMC to overcome both of those problems. To be more optimally damp the oscillation, the range of fuzzy membership is determined based on the minimum ITAE (integral of time absolute error) value while the rule is constructed based on the product between the sliding surfaces and its derivatives. To enhance robustness performance against disturbances and parameter uncertainties, the range of non crisp membership value (footprint uncertainty) of Fuzzy Type 2 is determined by considering the minimum sum of ITAE values at several conditions with different plant parameter. It is proved from the simulation that the proposed method can solve chattering problem more effectively and also more robust against disturbances and parameter uncertainties than T1FSMC.

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 magnetohydrodynamic nano fluid flow through porous cylinder

This paper concerns about the analysis of the effect of magnetohydrodynamic nano fluid flow through horizontal porous cylinder on steady and incompressible condition. Fluid flow is assumed opposite gravity and induced by magnet field. Porous cylinder is assumed had the same depth of porous and was not absorptive. The First thing to do in this research is to build the model of fluid flow to obtain dimentional governing equations. The dimentional governing equations are consist of continuity equation, momentum equation, and energy equation. Furthermore, the dimensional governing equations are converted to non-dimensional governing equation by using non-dimensional parameters and variables. Then, the non-dimensional governing equations are transformed into similarity equations using stream function and solved using Keller-Box method. The result of numerical solution further is obtained by taking variation of magnetic parameter, Prandtl number, porosity parameter, and volume fraction. The numerical results show that velocity profiles increase and temperature profiles decrease when both of the magnetic and the porosity parameter increase. However, the velocity profiles decrease and the temperature profiles increase when both of the magnetic and the porosity parameter increase.This paper concerns about the analysis of the effect of magnetohydrodynamic nano fluid flow through horizontal porous cylinder on steady and incompressible condition. Fluid flow is assumed opposite gravity and induced by magnet field. Porous cylinder is assumed had the same depth of porous and was not absorptive. The First thing to do in this research is to build the model of fluid flow to obtain dimentional governing equations. The dimentional governing equations are consist of continuity equation, momentum equation, and energy equation. Furthermore, the dimensional governing equations are converted to non-dimensional governing equation by using non-dimensional parameters and variables. Then, the non-dimensional governing equations are transformed into similarity equations using stream function and solved using Keller-Box method. The result of numerical solution further is obtained by taking variation of magnetic parameter, Prandtl number, porosity parameter, and volume fraction. The numerical results sh...

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.

Sedimentation characteristics study on the confluence of two rivers using Meshless Local Petrov-Galerkin Method

The process of sedimentation that occurred in the river can cause siltation of the river resulting in overflow of water to the surface or flooding. This siltation is caused by sedimentation. In this paper we consider sedimentation problem occured at the confluence of two rivers. We therefore develop a mathematical model of the problem and solving the model by using Meshless Local Petrov-Galerkin (MLPG) method. This MLPG method is an alternative way to solve this problem because it does not require mesh or grid. It therefore is very helpful in minimizing both running time of the numerical calculation and computer memory. From the results of numerical simulation we obtain that for the flow of the bend stream, there exists a decreasing in the height of the sediment is around 0002 and an increasing in speed of about 0.000848 during the initial velocity v = 0.1. When the initial velocity v increases, it will also increase in the speed and decrease in the height of the sediment. It can be occured when we put v = 0.9, an increasing in water depth of about 0.015832, increasing in speed of around 0.068586, and the height of the sediment decrease by approximately 0.166470. The both speed and depth affect the height of the sediment on the riverbed. Likewise, the height of the straight stream sediment increases about 2.792678, the speed decreases about 5.172373, the depth of the river is also down about 2.792678, when the first river debit and the second river debit are Q=0.5. If we put the first river and the second river are different, when the first river debit is 0.3 and 0.9 for the second river debit, sediment remained ride height is about 0.297025, the speed of the river downs about 1.651025 and the depth of the river decreases approximately 0.278835.