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Macbook Pro, cooling and the Venturi Effect...

kdum8

kdum8

macrumors 6502a
Original poster
Sep 8, 2006
919
12
Tokyo, Japan
Here's a question for the more technically minded of you. I have my MBP sitting on a flat, unperforated metal plate under my desk which I run an external monitor from. At the moment I have with the help of some little rubber feet, raised the laptop about 12mm off the plate ostensibly to aid with cooling by increasing the gap and hence the airflow underneath the notebook. However I was thinking about the Venturi Effect (http://en.wikipedia.org/wiki/Venturi_effect) today and realized that I may in fact be doing the opposite and making the cooling worse. Would it be better to just let the laptop sit on the metal plate without any extra gap as it was designed. This would surely enable the Venturi Effect and cool the laptop more than being raised, any thoughts? A slightly technical question for all of you physicists/engineers out there.

Cheers.
 
Air is compressible and as such the venturi effect will not really be present.

Having it rest on the metal plate is probably better as the thermal conductivity of the metal vs the air will transfer the heat away from the MBP faster.
 
Using the MBP on a metal plate works wonders. At my work, we have this metal shelf that slides out and thats where I use my MBP and it's the only place where it runs so cool. I use Avid on my MBP which really causes it to heat up but on that metal shelf, the casing may get a little warm but it's nothing to worry about.
 
thepandamancan said:
Using the MBP on a metal plate works wonders. At my work, we have this metal shelf that slides out and thats where I use my MBP and it's the only place where it runs so cool. I use Avid on my MBP which really causes it to heat up but on that metal shelf, the casing may get a little warm but it's nothing to worry about.
Click to expand...

Wow your setup sounds exactly like mine, except that I have raised my slightly off the metal plate. I guess I could try an experiment and see what works better in terms of fan speeds etc.
Is you MBP sitting directly on its rubber circular feet?
 
kdum8 said:
Yes generally but it works with gases too in certain situations.... a gas is a kind of "fluid" too in one sense.
Click to expand...

Gases are compressible.

Dkrtemp said:
I thought the Venturi Effect was applied only on fluids...
Click to expand...

It does.

kdum8 said:
Here's a question for the more technically minded of you. I have my MBP sitting on a flat, unperforated metal plate under my desk which I run an external monitor from. At the moment I have with the help of some little rubber feet, raised the laptop about 12mm off the plate ostensibly to aid with cooling by increasing the gap and hence the airflow underneath the notebook. However I was thinking about the Venturi Effect (http://en.wikipedia.org/wiki/Venturi_effect) today and realized that I may in fact be doing the opposite and making the cooling worse. Would it be better to just let the laptop sit on the metal plate without any extra gap as it was designed. This would surely enable the Venturi Effect and cool the laptop more than being raised, any thoughts? A slightly technical question for all of you physicists/engineers out there.

Cheers.
Click to expand...

Yes the extra spacing should help, but it will awkward to use the computer. Don't put metal to metal. If anything that is worse.
 
Since we're on the subject of cooling the MacBook Pros, does anyone have any cooling pads? Would there be any you'd suggest? I've been looking at one, can't remember what it's called though (fanless, something like $20 and is X-shaped). Thoughts?
 
alphaod said:
Gases are compressible.



It does.



Yes the extra spacing should help, but it will awkward to use the computer. Don't put metal to metal. If anything that is worse.
Click to expand...

Gases may be compressible but I am pretty sure that the venturi effect still works with air. As the space it moves through is reduced, the air should move faster, hence putting the notebook just above the just with a minimal gap should be the best option....
 
xUKHCx said:
Air is compressible and as such the venturi effect will not really be present.

Having it rest on the metal plate is probably better as the thermal conductivity of the metal vs the air will transfer the heat away from the MBP faster.
Click to expand...

Now I think about it gases can observe the Venturi effect, here are some examples in which it is seen:

Large cities where wind is forced between buildings;
A scuba diving regulator to assist the flow of air once it starts flowing;
In Venturi masks used in medical oxygen therapy;
Compressed air operated industrial vacuum cleaners
 
Venturi effect. It's there alright.

Strictly applies to fluids.

However the same is true of the Bernoulli effect - yet the venturi effect is used in carburettors (air) and the Bernoulli effect explains the functioning of aircraft wings - so all those nerds that deny what you say - adjust your glasses and tut all you like - the lady is right.

However- the compressibility of air means the effect is not uniform or regular.

Second consideration - aluminium is great and heat conductance (including by air flow) but no so hot (pun) on emissivity. That can be improved by using black paint on the underside - so you table does assist in dissipating the heat. As for losing the venturi effect - because of the compressibility it doesn't matter that much - a a larger space will ease volume restrictions - which allows higher thermal capacity in the airflow - which compensates some for the speed of air flow differences.

Or you could use a table with a vented base and additional fans...?
 
RhinoMan said:
Strictly applies to fluids.

However the same is true of the Bernoulli effect - yet the venturi effect is used in carburettors (air) and the Bernoulli effect explains the functioning of aircraft wings - so all those nerds that deny what you say - adjust your glasses and tut all you like - the lady is right.

However- the compressibility of air means the effect is not uniform or regular.

Second consideration - aluminium is great and heat conductance (including by air flow) but no so hot (pun) on emissivity. That can be improved by using black paint on the underside - so you table does assist in dissipating the heat. As for losing the venturi effect - because of the compressibility it doesn't matter that much - a a larger space will ease volume restrictions - which allows higher thermal capacity in the airflow - which compensates some for the speed of air flow differences.

Or you could use a table with a vented base and additional fans...?
Click to expand...

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