Tarti, Dwi (2025) Study Numerical of The Impact of Changes to Rear Windshield Angle and Reynolds Number on The Flow Characteristics Upper Side and Lower Side of The Saloon Car Model with Sharp and Rounded Corners. Other thesis, Institut Teknologi Sepuluh Nopember.
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Abstract
Penelitian ini bertujuan untuk menganalisis pengaruh variasi sudut kaca belakang (45°, 60°, 75°, dan 90°) serta bentuk sudut bodi (sharp corner dan rounded corner) terhadap karakteristik aliran pada bagian atas dan bawah mobil, serta terhadap koefisien drag (CD) dan lift (CD). Simulasi numerik dilakukan menggunakan perangkat lunak Ansys Fluent 2024 dengan mempertahankan sudut kaca depan sebesar 30°. Hasil menunjukkan bahwa peningkatan sudut kaca belakang cenderung meningkatkan nilai CD dan menurunkan CL. Model dengan rounded corner secara signifikan mampu menurunkan CD dibandingkan dengan model sharp corner. Nilai CD terendah sebesar 0,556 diperoleh pada model rounded corner dengan sudut 45°, sedangkan nilai tertinggi sebesar 0,8147 terjadi pada sudut 90° model sharp corner. Visualisasi aliran menunjukkan bahwa area wake membesar seiring bertambahnya sudut kaca belakang, terutama pada model sharp corner akibat adverse pressure gradient yang lebih kuat. Selain itu, peningkatan bilangan Reynolds menyebabkan aliran menjadi lebih stabil dan mampu mengurangi wake, sehingga nilai CD menurun. Hasil penelitian ini menegaskan bahwa bentuk sudut dan desain kaca belakang memainkan peran penting dalam optimalisasi energy losses kendaraan melalui pengurangan hambatan dan area wake.
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This study aims to analyze the effect of variations in rear window angles (45°, 60°, 75°, and 90°) and body geometry (sharp corner and rounded corner) on the flow characteristics along the upper and lower surfaces of a sedan model, as well as on the aerodynamic coefficients of drag (CD) and lift (CL). Numerical simulations were conducted using Ansys Fluent 2024 with the front windshield angle fixed at 30°, allowing for controlled comparisons across configurations. The results indicate that as the rear window angle increases, the CD value tends to rise due to an enlargement of the wake region behind the vehicle, while the CL value tends to decrease as flow separation patterns change. Rounded corner models demonstrate superior aerodynamic performance, significantly reducing drag compared to sharp corner models. The lowest CD value of 0.556 was observed in the rounded corner model with a 45° rear window angle, while the highest value of 0.8147 occurred in the sharp corner model at 90°. Flow visualization further reveals that adverse pressure gradients are more pronounced in sharpedged models, contributing to earlier flow separation and larger wake areas. In contrast, rounded corners mitigate these gradients, resulting in smoother flow reattachment and reduced energy loss. Additionally, higher Reynolds numbers provide greater flow momentum, allowing the boundary layer to better resist separation, thereby reducing the wake size and drag coefficient. These findings emphasize the critical role of rear window angle and body shape in improving aerodynamic efficiency and minimizing energy loss in automotive design.
| Item Type: | Thesis (Other) |
|---|---|
| Uncontrolled Keywords: | Energy Losses, Koefisient Drag, Koeficien Lift, Sudut Kaca Belakang, Wake, Energy Loses, Coefficient of Drag, Coefficient of Lift, Rear Windshield Angle, Wake. |
| Subjects: | T Technology > TJ Mechanical engineering and machinery > TJ165 Energy storage. T Technology > TJ Mechanical engineering and machinery > TJ561 Surface |
| Divisions: | Faculty of Industrial Technology > Mechanical Engineering > 21201-(S1) Undergraduate Thesis |
| Depositing User: | Dwi Tarti |
| Date Deposited: | 31 Jul 2025 09:21 |
| Last Modified: | 31 Jul 2025 09:21 |
| URI: | http://repository.its.ac.id/id/eprint/123802 |
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