Calculate Pressure Drag: Do-It-Yourself Wind/Water Tunnels?

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Discussion Overview

The discussion centers on calculating pressure drag on objects, particularly in the context of DIY wind and water tunnels for experimental testing. Participants explore methods for estimating drag without relying on computational fluid dynamics (CFD) software and share experiences related to building such tunnels.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Experimental/applied

Main Points Raised

  • One participant inquires about calculating pressure drag without CFD software and asks about the success of DIY wind/water tunnels.
  • Another participant mentions that while analytical solutions exist for simple objects, complex objects require CFD due to the dependence of drag on lift, ambient conditions, and object geometry.
  • A participant expresses concern about the lack of access to professional CFD programs and seeks recommendations for free alternatives.
  • One participant suggests that closed-form solutions are available for many objects and describes a simple method for building a mini wind tunnel using a vacuum cleaner and plexiglass, noting that results may not be publishable but can be useful for home experiments.
  • A participant specifies their interest in testing a high-powered rocket and expresses doubt about the accuracy of a DIY wind tunnel for their needs.

Areas of Agreement / Disagreement

Participants generally agree that calculating drag for complex objects is challenging without CFD, but there are differing views on the feasibility and accuracy of DIY wind tunnels for experimental purposes.

Contextual Notes

Participants highlight limitations related to the accuracy of DIY setups and the complexity of drag calculations, emphasizing the dependence on various factors such as geometry and ambient conditions.

Who May Find This Useful

This discussion may be useful for hobbyists, educators, and students interested in experimental fluid dynamics, particularly those considering building their own testing apparatus or exploring drag calculations for various objects.

Shawnzyoo
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Is there a way to calculate the pressure drag on objects?
without having to turn to CFD software?
thanks

also has anyone here ever built their own small wind/water tunnels for testing?
and how successful they were?
 
Last edited:
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For simple objects, such as a cylinder and with some basic assumptions there exist some analytical solutions. Unfortunately for anything complex, we all know the pressure drag or drag due to lift depends on the lift. The lift is dependent on the ambient conditiosn and the the geometry and material of the object. So in the end there is no easy way to calculate the drag of any complex object withoutthe use of CFD
 
thats what I was afraid of
are there any good free CFD progs to use?
i don't have access to progs like fluent
 
What kind of object are you interetsed in? There are many closed form solutions out there.

It is easy building a mini windtunnel you just need a vacuum cleaner and some plexiglass. Probably not publishable results but good for home experiments or classroom projects.
 
a high powered rocket is what I am doing
i have thought about building a windtunnel but i didn't think it would be nearly accurate enough for me
 

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