Floating/Rotation above computer fan

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    Computer Fan
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Discussion Overview

The discussion revolves around the feasibility of making a piece of paper float using the airflow from a computer fan. Participants explore the dynamics of air velocity around the fan and whether it can create sufficient lift for lightweight objects. The conversation touches on concepts of airflow, drag effects, and the mechanics of fan operation.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification

Main Points Raised

  • One participant suggests that the air velocity might be higher on the outside of the fan compared to the center, questioning if this could enable the paper to float.
  • Another participant challenges this idea, noting that the center of the fan is where the actuator is located, implying that airflow dynamics may differ from the initial assumption.
  • There is mention of drag effects potentially influencing air movement in the center, though the strength of this effect is uncertain.
  • Several posts diverge into discussions about Bitcoin mining hardware, including FPGAs and GPUs, which are not directly related to the original question about airflow.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the airflow dynamics around the fan, with differing views on whether the paper can float based on the air velocity distribution. The discussion also shifts to unrelated topics about Bitcoin mining, indicating a lack of focus on the original question.

Contextual Notes

Some assumptions about airflow dynamics and the effects of fan design remain unexamined, and the discussion includes various tangents that may distract from the core inquiry.

Mqrius
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I made this video a while back:


The black box is a bitcoin miner (irrelevant) with a fan that blows upwards just underneath the holes.
I was trying to make the piece of paper float. I think this should be possible since the air velocity is higher on the outsides of the fan than in the center. I seem to recall air "guns" that could float a light-weight ball in the air.

Is that actually possible or am I overlooking something?
 
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Physics news on Phys.org

or a better looking version..
 
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Welcome to PF!

Why would you think the velocity would be higher on the outside
 
russ_watters said:
Welcome to PF!

Why would you think the velocity would be higher on the outside
Thanks :)
The center of the fan is where the actuator is located, which means there's a column in the center that's not blown on directly. Perhaps the air there will still move due to a drag effect, but I don't know how strong that effect would be.
 
I never knew people did bitcon on their OWN hardware.

*cough* think about that the next time your CPU load spikes on a webpage with odd banner adverts :-)
 
d3mm said:
I never knew people did bitcon on their OWN hardware.

*cough* think about that the next time your CPU load spikes on a webpage with odd banner adverts :-)
Haha, although I can't deny that there are probably botnets mining Bitcoin, the large majority is actually people's own hardware. The main reason for this is that mining on a CPU is simply practically useless. GPUs are about a factor 100 faster at it, and botnets tend not to have very fancy GPUs.
The hardware shown in the picture is an FPGA (Field programmable gate array) miner, which is about a factor 5 faster than GPUs. Then there have been at least a million USD in preorders for ASIC miners, which are, again, a factor 10 better than FPGAs. They're due to be shipped somewhere in the next few months. Soon running a botnet for Bitcoin won't even be worth finding bots for.
 
I bought some for experimentation ages back when they were sub $1 then sold them when they went up. I haven't been back into bitcoin. It's going to be huge one day though.

Are those FPGA boxes what the bank R&D boys are using? I know some of them are looking at bitcoin.
 
d3mm said:
I bought some for experimentation ages back when they were sub $1 then sold them when they went up. I haven't been back into bitcoin. It's going to be huge one day though.

Are those FPGA boxes what the bank R&D boys are using? I know some of them are looking at bitcoin.
I don't know any bank people that are actively mining. In fact, banks and such are only starting to get interested now.

But as for people who have huge amounts of mining power, yes, the FPGAs are what is most commonly used at the moment along with GPUs. "The masses" still use only GPUs since they have those in their computer anyway.
 

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