Basic Physics Question

[ChrisA]

The root word of convection is "convey" (as on conveyor belt) which means to move. In convection the heat is tranported by amoving fluid. You body heats the fluid, t moves away and takes the heat with it.

In conduction the ocean is assumed to be a solid mass that your body tries to heat.

In my opion this is a silly question. Of course condution is required for convection. For convection to work heat is conducted intothe boundry layer and thne the boundry layer moves away and takes the heat with it.

 

[Walter]

to clarify, i agree there is a confusing element to that

from wetsuit to sea it is conduction, however with movement of water current and of the diver moving underwater on the wetsuit, convection has more effect than conduction....

It's not at all confusing. Yes, convection takes place in the ocean (lake, river, etc.), and it may move heat acquired from your body around, but convection has nothing to do with your heat loss, that is conduction. That is, of course, unless part of your body is actually flowing out of your body and into the ocean.

 

[paolov]

It's not at all confusing. Yes, convection takes place in the ocean (lake, river, etc.), and it may move heat acquired from your body around, but convection has nothing to do with your heat loss, that is conduction. That is, of course, unless part of your body is actually flowing out of your body and into the ocean.

ah no confusion on the difference on convectin and conduction... the confusion was int he statement i made earlier on.. it was a bit not specific ... that was the conusion i wanted to clarify.

we agree on conduction !


.

 

[ScubaJorgen]

Just started my D/M classes and am doing the diving encyclopedia workbook. One of the first questions has to do with Convection and Conduction. asking which one affects a diver more in terms of heat loss.

Is a bit of apples and pears.

Like stated, there are basically two processes to loose heat
- conduction (contact between bodies is needed. Hot body transfers heat to cold one)
- radiation (heat is lost by sending radiation)

For a diver in water, conduction is the main process. In the process of conduction the temperature difference between diver and water is what counts. The higher the difference, the faster the heat loss.

Convection (conduction to a flowing medium) is deteriorating heat loss by conduction. Without flow, the diver heats the water that surrounds him/her, slowing down heat loss. With flow, the heated water is immediately replaced by cold water, maximising heat loss.

So the question: what is worse, convection or conduction basically is not quite right. The question should be: What is the influence of flow (due to the diver swimming) to the conduction? In air, flow makes a hell of a difference. In water it may be less effective, because water already is a good heat conductor. But that is a feeling...