Lift induced drag

I am trying to visualize the lift-induced drag in SimScale , but I couldn’t find any.
My understanding of lift-induced drag is that they should manifest as rotation on the tip of wings, but I could not see any of these from the vector graphs.
Moreover, from the force plots, I see that Simscale disects the drag into “pressure” and “viscous” forces. I wonder is lift-induced drag lumped into either pressure or viscous, or is it not shown in the force plots, or perhaps my example theoretically should not have lift-induced drag?
I tried to search for example projects in Simscale, but although many tutorials describe lift-induced drag from an academic point of view, none of them really showed the concept in a Simscale project.
I wonder could someone point me to good resources regarding lift-induced drag, ideally in the form of a Simscale project?

Hey there!

I am no expert in aerodynamics, perhaps some other user with more knowledge can add to my response.

If this lift-induced drag is a phenomena created due to the deformation of the wings, then it won’t be captured by the Incompressible flow solver, as it assumes that all boundaries are fixed.

For this, you would need a Fluid-Structure Interaction solver, which computes the evolution of the drag as the wing is elastically deformed due to the aerodynamic forces.

Sadly, such solver is not currently available in SimScale. Perhaps we could add some feedback for our product team, if you describe in what professional application this would be needed and the key benefits over regular aerodynamics simulation.

Hello ohuli, first of all have you tried a particle trave around the spoiler, that would show you the vortices of the induced drag? If you have, I think I might have come up with an explanation.

Explanation 1 - I will check when I get home but it may be that there isn’t a significant difference of preasure between the top of the spoiler and the bottom of the spoiler, ultimately causing there to be little to no vortices.

Explanation 2 - this might be due to airflow over the side causing the vortices to not be generated if you know what I mean due to some strange phenomenon

Explanation 3 - you see this alot on airplane wings and one of the reasons could be the angle at which the spoiler is at could be affecting the induced drag from wing vortices now there could also be induced drag from the downwash which may be affected by the angle of the spoiler

I will have a closer look at this when I get home because I’m on mobile right now, hope that helps,

Frank lucci

Hello ohuli it turns out there is rotation at the tips of the wing(aka wing vortices) you just weren’t looking for them in the right way. You should use a particle trace to find this then look at it from the back here is a screen shot

you can see the rotation you were talking about at the tip of the wing/spoiler

you should also consider running the simulation longer and try comparing the mesh to a standard mesh

have a good one,
Frank Lucci

Wow, wow, wow, this is the most fantastic graph I have ever seen! Thanks Frank!

In addition, I wonder if you could help me find out how to get the “induced lift drag” quantitatively form the force plots?

I see that in the above plot, Simscale disects the force into “pressure” and “viscous” components, which I understand as corresponding to form drag and skin friction drag.
I wonder where does “lift-induced” drag come into play?

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Hello, again ohuli, I would recommend increasing the run time to about 2400s on the simulation because the things like domain and inlets in your convergence plot are not fully balanced out yet, then they will hopefully be close to accurate😁. I believe this is taken into consideration under either pressure or viscous force, but I don’t completely know which one.

here is a conversation about that consideration for lift induced drag - Does Simscale Solve For Induced Drag and Turbulent regions

conclusion - I don’t fully know if it is in viscous or pressure force, but my guess is it is because you probably wouldn’t be able to see the picture of the spiral if it wasn’t for the mathematical model
which I don’t see a reason why it would be in the visualization and not the graph, but to my knowledge, they haven’t added a separate graph line that is only for induced drag which means it is probably under either pressure or viscous, don’t know which one though
(ps. make sure to run the sim a bit longer like described above)]

this has been a cool thing to get me thinking throughout the day,
hope that helps :grinning:,
Frank Lucci

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Really thanks for your very detailed explanation, and suggestion on the run time of the simulation, which I will be trying!
It’s a pity the feature you requested in your previous thread wasn’t picked up, I have tried to submit this idea to Simscale.