# Obtained coefficients that were significantly different from the author's wind tunnel

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January 12, 2023, 12:54
Obtained coefficients that were significantly different from the author's wind tunnel
#1
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Renz
Join Date: Jan 2023
Posts: 7
Rep Power: 2
Hello, I'm new to this software; could you possibly assist me in finishing my undergraduate thesis? This is the only activity I must complete in order for me to graduate. I am currently attempting to obtain lift and drag coefficients @ 100k Reynolds number from my CFD 2D Simulation using Fluent ANSYS. However, I obtained significantly different coefficients from the author's wind tunnel test results (for validation). I used the following setup:
1. Viscous Model: k-omega – SST model, as shown in Figure1.
2. Inlet: ****Please see Figure2. This is for 0 angle of attack.
3. Reference Values – Area is 0.1m^2 with Depth 1m, and Length 0.1m. Left the rest as their default values, as depicted in Figure3.
4. Solution Method: ****Please see Figure4.
5. Report Definitions: Drag and Lift settings are shown in Fiugre5.
6. Residual: Absolute Criteria was set to all 1e-07.
7. Initialization: Hybrid Initialization.
8. Run Calculation: Number of Iteration at 1k.
9. The airfoil’s dimension is 100mm. Density is 1.225 kg/m3. Dynamic Viscosity 1.7894e-05.

////// Everything that I didn’t mention were set to their respective default settings and values //////

\\\ Other figures are uploaded on the reply section because the # of uploaded pictures are limited.\\\\

To vary the angle of attack, the airfoil is positioned horizontally while modifying the flow direction in both the X and Y components using the cosines and sines of radians of the angle of attacks. For example: cos [radian (1°)], and sine [radian (1°)] – I saw this on YOUTUBE. A NO-slip conditions was applied to the airfoil surface.

I am using a rectangular-type domain with structured boundary layer grid around the airfoil and an unstructured grid in the outer domain, as illustrated below in Fig 7. It contains over 52k components in total.
Attached Images
 Fig1.jpg (92.2 KB, 3 views) Fig2.jpg (61.9 KB, 2 views) Fig3.jpg (36.3 KB, 2 views) Fig4.jpg (59.4 KB, 2 views) Fig5.jpg (71.2 KB, 3 views)

January 12, 2023, 12:57
Other figures
#2
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Renz
Join Date: Jan 2023
Posts: 7
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Other figures
Attached Images
 Fig6.jpg (69.1 KB, 3 views) Fig7.jpg (144.6 KB, 3 views) Fig7_1.jpg (146.4 KB, 3 views) Fig8_1.jpg (50.8 KB, 2 views) Fig8_2.jpg (50.6 KB, 3 views)

January 12, 2023, 12:58
Other Figures part 2
#3
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Renz
Join Date: Jan 2023
Posts: 7
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Other Figures part 2
Attached Images
 Fig8_3.jpg (50.6 KB, 3 views)

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