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pHaestus said: ...flow rate (Q) is not what really is relevant to cooling; fluid velocity (Q/area) is what carries through in all heat transfer and turbulence calculations.
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While that is true it is not totallly complete. Velocity is related to the rate that heat is transfered into a liquid, (how fast the WB will give up it's heat to the water). How much heat is transfered is related to the volume of water flow.
Think of it like this: if you increase the velocity you lower the deg C/watt, if you increase the flow you increase how many watts will be transfered.
One tiny little channel might get a very fast velocity but wont have that much flow so it will transfer heat very efficiently but cant move a whole lot of it. Conversly if you have one very big channel it's velocity will be small but it's flow will be big giving you a very inefficient transfer but it will move lots of watts of heat.
This is the biggest problem WB designers have in creating a high performance WB. High flow is easy to get all by itself. High velocity can be created (with loss of head). But doing both at the same time is a very tricky problem.
I know I went a little off topic but maybe this will help some of those out there who havent read up on fluid/thermodynamics.
Have a great day!
