Calculating drag [+lectures and books on Fluid Mechanics]

I’d like to be able to calculate drag. Here is a lecture series on that:

Physics - Fluid Dynamics (19 of 32) The Drag Coefficient – Michel van Biezen

Notice how the drag coefficient of a streamlined body is 0.04, versus 0.82 for a long cylinder.

Physics - Fluid Dynamics (20 of 32) Force Due to Drag Coefficient – Michel van Biezen

I don’t think anyone is calculating drag manually anmore, especially for custom airfoils.
I’d say looking at drag polars and then simulating is the way to go.
@tallakt How do professionals estimate drag?

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Hehe. Im a software guy. In kitemill we use numerical calculation of lift and drag relative to airflow. There is a software called xfoil that does a decent job at it I believe. I have not been involved in this though


Xfoil from Mark drela, original version up to something like 1980’s is still the best open tool available.
Also airfoil tool that compute many calculation performed on Xfoil is really useful.


Btw: yes by pure luck I’m a paid professional in this business. That doesnt necessarily mean that I know a lot of stuff. I think the biggest differene between me now and me a while ago, before I started in my current job is that now I have seen Kitemills rig inflight many times. This has adjusted my views on what is important and not. But there has not been sudden insight dealt to me. Anyone could make a better guess than me in most issues AWE…

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4 posts were merged into an existing topic: Tip Speed Ratio

Intro to Reynolds number:


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Fluid Mechanics I - Dr. Biddle’s lecture series

19 videos 646,947 views Last updated on Aug 11, 2018

Fluid Mechanics II - Dr. John Biddle’s lecture series

17 videos 65,230 views Last updated on Apr 11, 2019

(Audio corrected) National Committee for Fluid Mechanics Films (NCFMF) 18 videos 5,340 views Last updated on Oct 30, 2015]

Videos 10, 12(1), 12(2), 12(3), 12(4), 18, 20 missing in the above playlist, they are in this playlist:

NSF Fluid Mechanics Series 25 videos 487,293 views Last updated on Aug 17, 2014

Turbulent Flow is MORE Awesome Than Laminar Flow – Veritasium (YouTube video)

r/aerodynamics - Vector illustrations for Aerodynamics and Fluid mechanics

It would be wonderful to be able to rely on computers to design fluid structure interaction systems for us
Even with the best of machine learning
I fear It’s still going to take a huge amount video of laser lit flying in fog (and wind) to get any useful output

Nice clean explainer video of the techniques being explored

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Another video in the same series is much more encouraging in terms of how much data you may need to start with to actively develop a good working control model from

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Looks to be a somewhat random order. The NPTEL series seems to be watchable and thorough. Tom Avraham links to other resources.

In Desmos:

I was able to set up a 2D openfoam cfd quite easily. Very plexible, but apparently JavaFoil is better for drag calculation

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I’ve now discovered the CfdOF workbench in FreeCAD which uses OpenFOAM. I’ll likely use that.