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Unread 10-14-2002, 07:58 AM   #129
Cathar
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Join Date: Sep 2002
Location: Melbourne, Australia
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Quote:
Originally posted by GeminiCool
Reading my post this morning, I agree it is very unclear, and I see where you have been mislead. The Velocity through both fittings in a closed loop system is the same, ok sorry didn't mean to imply that it would be different.
Before we go further, let's correctly define out English terms:

Velocity does not equal flow rate.

Flow rate = volume / time
Velocity = distance / time

For a set given flow rate, the velocity will be increased as the same volume of water per unit of time is forced through a smaller opening.

Thus velocity will only be equal through a system of uniform orifice sizes.

In summary:

The sum of resistances defines a fixed flow rate when those resistances are applied against a pump's pumping pressure.

It is perfectly valid to make comparisons of a system of a certain flow rate regardless of how that particular flow rate was achieved, whether that be through squeezing the hose, using a smaller capacity pump, or using a powerful pump but with lots of restrictions (note - we are ignoring pump heat in this scenario).

With respect to your variety of scenarios, each scenario you presented represents a particular flow rate due to the restrictions that those scenarios offered against the pump. The end result would bea particular flow rate unique to each scenario. The water-block's performance is dictated purely by flow rate (given a set coolant temperature and a set heat load) regardless of how that particular flow rate was arrived at.

You presented a set of slightly different restriction scenarios, but the exact details of those scenario's is unimportant. The only important detail is the resultant flow rate as a result of those restrictions.

I hope that clears it up.
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