Hello, I would like to ask if the Drag i get via the incompressive flow analysis, is about the total Drag of my body. This is because i simulating a Wing, but the results i get in theory (calculating the parasitic Drag+ the induced Drag) are differnet fron that on the software …So, can you tell me…

What is the resultant total drag you get right now? I also realized that you don’t include the viscous force in x direction to your total drag sum which is around 2.91 N.

Hello kkatsaflioglou, thanks for reaching out to us. i think there is a misunderstanding about how the drag in the CFD solution is calculated. The difference between the CFD solution and the theoretical value is that in the CFD we solve the complete flow field around the wing, whilst in the theor…

This is my Wing Project with the follow specs Wing Area: 1,182m^2 Wing span: 3,430 m Aspect Ratio: 10 *Oswald factor e: 0,76 Weight (Lift expectet— L=W): 323.73 N Speed : starting point is 25m/s…but the wing has leading edge Sweep angle Λ=4,5deg. (V=V0cosΛ=24,92m/s) at ρ=1,225kg…

Hello @kkatsaflioglou , thanks for sharing these information. Sebastian already made some great points. I’ll also have a few comments according to latest info you just shared. -First of all, weight and inertia are never included in static CFD simulations such as this one. Weight can only be used to…

Thank you for the support -i only get the zero-lift cd from airfoiltools. com…in case that the true zero-lift drag is different…that does not provide such a difference in the total Drag. -I set the AoA in the CAD mode…setting the rotation in z-axis

Zero-lift Cd (Cd_0) only assumes an infinite wing meaning that effects of vortices near the wing tip will not be counted due to lift or pressure difference between both sides. Cd_0 still consists of drag due to pressure and drag due to shear, and these values may not be very accurate while using pan…

I set a new (smaller) zero-lift cd in the parasatic drag (1/2 ρ V^2 Cd_0 s) but aggain the results are much bigger…what im doing wrong? i know that the equation i used is not supper accurate but aggain it is a lot of difference between my calclulation and the CFD results.

oh, i forget it…my theoretical resaults are 15,15N…now the resaults from simulation are 11,15+2,91=14,06N. I think now we are pretty close

Great! Rest of the difference may be due to several factors really such as: the fidelity of the tools, oswald efficiency, etc. But in general I would say that it’s a pretty successful comparison with theoretical values. Best, Kaan.

SimScale CAE Forum

Calculating Drag

Using SimScale Fluid Flow / CFD

kkatsaflioglou December 15, 2022, 4:44pm 11

Thank you a LOT…you are great!!!

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