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This study discusses the fluidic oscillator using computational methods. The analysis was carried out in a transient state with the URANS equation. The turbulence model used is k-ω SST. The fluidic oscillator was analyzed by varying the size of the fluidic oscillator by doubling the baseline and reducing its size by half. The analysis was carried out using the magnitude velocity curve to time changes, velocity profiles, and fluid flow contours. Based on the results of the velocity analysis at two points, it can be concluded that the fluidic oscillator can produce an oscillating fluid flow with a maximum velocity of almost eight times the inlet velocity. Meanwhile, the velocity profile in the feedback channel is alternately positive and negative due to the backflow phenomenon. In the mixing chamber, an adverse velocity profile can also be found, indicating the mixing flow's presence. Based on the magnitude velocity analysis results, it can be concluded that changing the dimensions by increasing the size of the fluidic oscillator does not produce significant changes. Meanwhile, the velocity profile on the feedback channel shows a significant change in model 3. The velocity contour shows that at t=4 s, the fluid from fluidic oscillator model 1 has lost its oscillator effect. However, this is not the case with the model 2 and 3 fluidic oscillators. [ABSTRACT FROM AUTHOR]

The aerodynamic characteristics of MPV vehicles were studied to obtain comprehensive information. The study was conducted computationally using the RANS equation on the k-ω SST turbulence model. The three vehicles selected in this study are Vauxhall Zafira C Tourer, Volkswagen Touran, and Mazda MPV II 2.3. These vehicles were chosen because they are quite in demand in Indonesia. Each vehicle was analyzed at three different speed variations, namely 20 km/h, 50 km/h, and 100 km/h. This research aims to study the characteristics of the drag coefficient (Cd) of several MPV vehicles. In addition, this study also analyzes the effect of changes in speed on the drag coefficient and its causes. The result of this research is that when viewed from the Cd point of view, the Volkswagen Touran has the smallest drag among the other two vehicles. From the Cd point of view, it can be seen that the Volkswagen Touran has the smallest drag, i.e., 0.75620101 at 20 km/h, 0.782 at 50 km/h, and 0.786 at 100 km/h. It was found that at a speed of 20 km/h, the Volkswagen Touran is still the best because the Cd is small and the power is small at 60,3126 hp. Then at a speed of 50km/h from the point of view of drag and power, the Volkswagen Touran vehicle is superior because the Cd produced is the smallest, and the average power is not much different from each other. At a speed of 100 km/h, the Volkswagen Touran is still superior because of its smallest drag and slightly less power when compared to other vehicles. Overall, when viewed from the Cd and power, the Volkswagen Touran is a superior MPV car because the Cd produced is small, and the power is also efficient. [ABSTRACT FROM AUTHOR]

This study uses a computational research method with a Computational Fluid Dynamics (CFD) approach. The governing equation used in this research is Reynolds Averaged Navier Stokes (RANS) with turbulence model. The type of airfoil used in this research is the NACA 4415 asymmetry airfoil. Airfoil testing is carried out on variations in Angle of Attack (AoA) and leading-edge models. The Angle of Attack tested in this paper is in the range of 0°-25°. The first modification of the airfoil is to make the airfoil's leading edge in the form of a spinner dolphin. The second modification is to shape the airfoil's leading edge like a rough-toothed dolphin. Modifications to the spinner dolphin proved to have better aerodynamic performance than the rough-toothed dolphin, although there was no significant difference. The optimum AoA achieved by the spinner dolphin is AoA = 8°. Based on the baseline comparison, the percentage of drag on the spinner dolphin was reduced by 5.6162. While on the rough-toothed dolphin, it decreased by 4.9116. [ABSTRACT FROM AUTHOR]