Talk:Convection

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Contents

[edit] Miscellaneous

Someone has vandalised this page by replacing 'fluid' with 'poo'. Is there someone who knows how to restore it to its previous version? 7/11/2006 - Lti

You go to history and pick a version just before the change, and do "edit" then "save". Or if other changes have been made since then, you manually bring up the latest version and manually change the word then save. SBHarris 01:26, 8 May 2007 (UTC)

I thought it would be good to add that much study of convection also relates to motion of fluids such as water, in solar energy and HVAC. --User:Jdpipe

This definition of convection as a heat transfer mechanism is archaic. It might be a natural physical phenomenon relying on gravitation but it is no more a heat transfer mechanism than picking up a red hot poker and plunging into a bath of cold water.

Don't understand what you're trying to say. There's nothing archaic about it. It is a mechanism of heat transfer. Without gravity, a forest fire as you know it would be impossible. The best that would happen is everything would sit and smolder slowly. A poker into water is a specific example of a physical system. We're talking about mechanisms which transcend the specific materials. SBHarris 01:26, 8 May 2007 (UTC)

It might be more useful today to relate this process to efficiency. For example forced convection is quicker than natural convection, a heatpipe can tanfer more heat for a given volume etc. Transfer through use of Latent Heat exchange is also an extremely important mechanism. What would we call heat movement in a non-gravity situation caused by diffusion of a gas? User:rjstott

Just simple heat transfer by diffusion. There may be more efficient processes than convection, but there aren't many of them. SBHarris 01:26, 8 May 2007 (UTC)

[edit] Equation with integral

In the equation that has the integral with apparently As as the lower limit, the subscript s for As does not show well. The s looks likes it's part of the integrand instead of the lower limit. I'm not sure at this time how to fix this problem. H Padleckas 11:06, 9 Jul 2004 (UTC)


[edit] Thermal convection, Rayleigh-Benard convection, Maringoni convection, Solutal convection

Thermal convection redirects here, but isn't mentioned in the article. Is it superfluous (is all convection thermal)? Also, Weisstein's physics encyclopedia says that thermal convection is also called Rayleigh-Benard convection. This web page says that, "the stripe or roll state formed in bouyancy driven convection is today referred to as Rayleigh-Benard convection. Surface tension induced convection is known as Maringoni convection." -- Kjkolb 00:50, 28 November 2005 (UTC)

I also found something called solutal convection, but I've been unable to find out its definition. -- Kjkolb 02:59, 28 November 2005 (UTC)

There is also granular convection, where vibration in a bed of granular material causes vertical circulation. Will.Brunner 05:08, 28 January 2007 (UTC)

[edit] fluid

Adding after the use of 'fluid' in the first paragraph "which can be a liquid, gas, or plasma" would help readers who see fluid and think that it means liquid, which I am guessing is not an uncommon mistake.

--Akako|☎ 00:15, 28 May 2006 (UTC)

[edit] convection and HVAC

For my part, I was hoping to find here a discussion relating to HVAC and ovens and how convection heaters and convection ovens differ from the conventional kinds--or whether the term in those cases is misapplied in some sense.

Thanks.

[edit] Pattern Forming

The pattern forming section is very confusing (even to someone who understands convection already). It should probably be removed or at least moved to its own article. Anonymous6494 06:13, 4 December 2006 (UTC) It also means that it is international current of the movement of the fulid.

[edit] Heat transferred from Earth's surface by convection?

The beginning of the Atmospheric Convection section begins: In the case of Earth's atmosphere, solar radiation heats the Earth's surface, and this heat is then transferred to the air by convection. Since the earth's surface is not a fluid (cf definition up top), use of "convection" here strikes me just plain wrong. Shouldn't the transfer from Earth's surface to the air be by either radiation or conduction? The convection will pick up after that.

68.166.104.2 19:38, 23 February 2007 (UTC) JP

You're right, of course. I think it means to say "transferred away into the air by a mostly convective process". That first little bit where the air molecules hit the ground and come away faster isn't convection, nor is heating of air by radiation, but overall it's mostly a convective process, and not worth complicating here by going into it finely. I'll fix it. SBHarris 01:29, 24 February 2007 (UTC)

[edit] Oceanic Convection

On March 6th, someone changed the last word of the paragraph under Oceanic Convection from "heat" to "hell". I changed it back.

Was: "In this case it is quite possible for relatively warm, saline water to sink, and colder, fresher water to rise, reversing the normal transport of hell."

Is now:"In this case it is quite possible for relatively warm, saline water to sink, and colder, fresher water to rise, reversing the normal transport of heat." —The preceding unsigned comment was added by Doodit (talk • contribs) 16:40, 15 March 2007 (UTC).

[edit] Diffusion vs convection

Yesterday i added the comparism to diffusion in the article about convection. You edited my add. You 're right, "internal force" is misleading and "brownian motion" ist the correct discription of the physical process. But you also edited the term "caused by an external force such as gravity or heating" by "convection is a relatively large-scale effect, involving bulk fluid motion." I think yor 're right with the discription "how convection looks like" but you deleted what is the REASON for convection, and I think the reason is a (macroscopic) external force due to gravity, pressure difference, temperature difference and so on. For example in fuel cells technology forcing a liquid to move through a porous media is denoted by convection. —The preceding unsigned comment was added by 129.187.5.225 (talk) 08:54, 8 May 2007 (UTC).

(Above comment copied from my talk page) I don't disagree with your statements about the driving force for convection, but I feel it's covered sufficiently in the article text, and doesn't need to be discussed in that much detail in the introductory paragraph. What do the other editors think? --Slashme 10:31, 8 May 2007 (UTC)

[edit] Convection & Advection : Definitions

Reference : Wicktionary.

It appears to me that these two terms -- as they appear in this article and in the Wiktionary -- need to be harmonized. —Preceding unsigned comment added by 70.157.173.219 (talk) 06:34, August 30, 2007 (UTC)

[edit] Section on Natural Convection looks sabotoged

The section on Narural convection seems to be non-sensical. It talks about effects of gravity from Mars on Earth. It uses an Equation that has T to the fourh power which is for radiative cooling. —Preceding unsigned comment added by 71.206.168.67 (talk) 14:37, 25 November 2007 (UTC)

I have changed it, it was caused by vandalism. Seddon69 (talk) 16:40, 25 November 2007 (UTC)

I removed the whole chunk about radiative heat transfer. --Slashme (talk) 06:52, 26 November 2007 (UTC)

So were does conduction settle in this? —Preceding unsigned comment added by 76.226.233.73 (talk) 00:49, 12 March 2008 (UTC)

[edit] Could this image be used in the article?

Are there any objections to using this image in the article?

image:Hobo_stove_convection_2.jpg
Description: Cutaway illustration of a hobo stove including air convection
--Dave (talk) 21:20, 16 May 2008 (UTC)