[titanan]

Originally Posted by arjun

You say that force values are correctly calculated but then the cd value doesn't match the velocity profile you are showing. On top of that you are using fluent and i find it hard to believe fluent got the pressure so wrong that its integral on the surface is so off.

I can't comment much on it without knowing

1. Dia of sphere.
2. Free stream velocity and density of fluid

And
3. Force value reported by the solver.

You say all these are okay but in the end cd doesn't match up.

Anyway is it possible for you to share the fluent mesh (.msh) and let us know the free stream velocity. I can try myself in my solver (which is very much like fluent).

Hey.
I concluded that the cd value is not correct but the drag value is correct. Sphere radius:25cm freestream velocity:30m/s . In these conditions it calculates around 35N of drag which means a cd of around 0.3 should be the answer which is close to the experimental results. But the cd ansys calculates is much lover at around 0.01 . I think the problem is at this calculation ansys makes. I did another calculation with the same sphere but at a 0.3m/s freestream velocity and 5.5e-03 N drag was expected. Resoults gave 5.2e-03 N which is pretty close. I will try to find the couse of the incorrect cd calculation but at that point it is not as important since the drag force values seems correct and ı can calculate the cd myself. Here is the mesh file you asked for https://file.io/yfFcUX9iOhpQ
Thanks for your help

[LuckyTran]

So.... did you check the reference values?


So now you understand why we asked for raw drag forces

[titanan]

Originally Posted by LuckyTran

So.... did you check the reference values?


So now you understand why we asked for raw drag forces

Hey
Yes ı checked the reference values. They seem correct. I see why you wanted the drag force values, should have checked them earlier.
Thanks for the answer.

[LuckyTran]

So what are the reference values......? If the drag force is correct then the only thing that can be wrong are the reference values. Surely, everything can't be right!

[arjun]

Originally Posted by LuckyTran

So what are the reference values......? If the drag force is correct then the only thing that can be wrong are the reference values. Surely, everything can't be right!

I think fluent only wants two references here, free stream velocity and the area.

[tusin111]

Originally Posted by CFDfan

Something is probably wrong with your postprocessing. If the flow is in X direction, then CD=2*Fx/(ro*V^2*S), where S=0.031415, V=30 and ro=1.206 (or whatever ro_air you have used).
I got CD=0.09 without any mesh tuning and Realizable k-e.

Hello, I am also analyzing to find the drag coefficient of a sphere, but at re=400000, the drag coefficient does not come out as 0.1 but as 0.4. This is a very high figure.

So I'm curious
What turbulence model did you use and what cfd program did you use? And can you tell me what the range of y+ is?

Oh, and did you use Structured when working on the mesh? Or did you do it with Unstructured?