Talk:Drag coefficient

message: The previous version stated that the drag coefficient, for a sphere, increased from 0.1 in laminar flow to 0.47 in turbulent flow. This was wrong since in laminar flow, Stokes equation applies, i.e. Cd = 24/Re, which gives high values at low velocities and Reynolds numbers (Re).  —Preceding unsigned comment added by Cbriens (talk • contribs) 06:21, 31 January 2010 (UTC)
replies: text: Why removed the diagram ? Dear editors,Please read discussion page for Drag coefficient CD and leave no blanks in wikipedia article after your works, or no discussions.will inherit by lazy editors, thimk twice of yours trim and be kind to post a notification to the open questions.Myself I will have no reason but leave Wikipedist  — Preceding unsigned comment added by 188.25.59.135 (talk) 02:00, 30 September 2023 (UTC)
thread_title:  Correction 

message: The article changes from imperial to metric measurements half way through - could be clarified - Cd measurements are given for the cars in both, meaning that they differ by a factor of 10.7. —Preceding unsigned comment added by  (talk • contribs) 
 
This statement is absolutely ridiculous.  As an Aero student, I can assure you that the Cd value is entirely unitless, and the reference area determines the units of the answer (as does, if one is observing the entire drag equation, velocity and density).
: I am afraid that this statement is not ridiculous at all. In the metric world, Drag D = Cd*½*ρ*V^2*A. D in Newton, dynamic pressure in N/m^2, and area in m^2. In the USA, D = Cd*ρ*V^2*A, not sure what the preferred units are. The factor ½ has disappeared into the Cd, which must also account for air density being in obscure units etc. In the footpound world, physical equations usually contain some sort of constant, required because of the lack of any logic at all in defining the units. How strong was the horse of the horsepower definition? What size foot was the proto for the length definition? Koyovis (talk) 01:19, 7 April 2013 (UTC)
thread_title: Unclear combination of metric and imperial

message: The Cd for an hemisphere is stated in the article chart as 0.42, while an Sphere is attributed 0.47, thus the Sphere having more drag under the same air flow than the Hemisphere. It sounds strange that an Sphere, even when not fully streamlined, but looks as more Streamlined than an Hemisphere, may have a worse, higher drag, higher Cd, and from a non-experimental, intuitive point of view, one will tend saying that the Cd of an Hemisphere is worse, higher than of an Sphere, and that the figures in chart should be interchanged, Sphere Cd= 0.42, Hemisphere Cd= 0.47. How rigt or wrong is this rationale?. To what extent Cd figures of an Sphere and an Hemisphere may result in different actual drags according to speed and Reynolds number? For common people, the involved fluid almost always would be Air, that anyway can change in density because of temperature and height of place, humidity content...
Thanks. Salut +--Jgrosay (talk) 22:46, 16 December 2014 (UTC)
thread_title:  Drag coefficient of an Sphere worse than of an Hemisphere? 

message: As in picture "Drag coefficients in fluids ..." compared to "Flow around a plate ...": 
I believe it would be quite advantageous for many readers to keep this direction uniform. 176.7.136.147 (talk) 08:22, 4 February 2024 (UTC)
thread_title:  shown direction of relative movement between Fluid and object