Red vs Re: Clarifying an Equation Mystery

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Re[SIZE="1"]d refers to the Reynolds number calculated using a specific characteristic dimension, typically the diameter in pipe flow scenarios. In contrast, Re without a subscript is a more general representation of the Reynolds number. The distinction is important for accurately analyzing fluid dynamics in various contexts, such as flow past flat plates or cylindrical objects. Understanding the specific characteristic dimension used in calculations helps clarify the application of the Reynolds number. This differentiation is crucial for proper analysis in fluid mechanics.
Kenny Lee
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Hi, this is going to sound very stupid.
Is Red the same as Re?
Its just that in some equations, I have Red, and then in others Re. It might not sound like much of a problem, but I'd really appreciate if someone could clear things up for me. Thanks!
 
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Reynolds number with a subscript usually pertains to the RE with respect to a particular characteristic dimension of an object. For example, in a lot of problems looking at flows past flat plates, you will see RE_x for the RE along the length of the plate measured from the leading edge of the plate. Perhaps the usage in your case is the flow past a cylinder or sphere.
 
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ohh right. Diameter, that's what it stands for. Its pipe flow. Thanks!
 

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