# Questions tagged [convection]

transport mechanism involving bulk motion of a medium

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### Physics of the convection oven

I don't understand how convection ovens can cook food faster than radiant heat ovens. Guides to convection ovens claim that they cook food 25-30% faster than radiant heat ovens, but do not really ...
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### Why don't the "trapped warm air" just fly out of the holes in blankets?

I've read a lot of explanations that the holes of a blanket somehow trap air which keeps the air in place.(including this: https://www.reddit.com/r/explainlikeimfive/comments/10lj0h/...
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### What causes the lamp above my gas stove to swing like a pendulum when the stove is on?

There is lamp hanging above my gas stove, which when the stove is turned on performs pendulum-like oscillations in an oval trajectory, not unlike the dynamics of Lissajous patterns. The lamp is ...
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### The local and average Nusselt number in a square cavity

I am in the process of programming the local & average Nusselt number in a left vertical wall but my Matlab script gives me inappropriate values and it doesn't change with changing of Rayleigh ...
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### Average Nusselt number and heat transfer coefficient

For the flow over a flat plate of length L, how the average Nusselt Number over a length L is equal to $$Nu_{avg} = \frac{h_{avg}L}{k_f}$$ where $h_{avg}$ is the average heat transfer coefficient over ...
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### Gas to solid heating?

I am doing a study on the phenomenon of pyrolysis. This is purely a study of the underlying physics. Generally, in practice, pyrolysis feedstock is heated conductively but we are examining the energy ...
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### Convection from rapidly evaporating liquid inside vacuum chamber?

If we have a liquid that is is being actively heated and is rapidly evaporating (let's say around 1g/s for Ag at 1500K) inside a vacuum chamber, can convection around the liquid/vapor interface occur ...
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### Small parameter expansion to obtain convective heat transfer solution of the heat equation

I'm trying to follow along with this paper on perturbative transport analysis. The section I'm stuck on analyzes the heat equation in 1D slab geometry. To get a diffusion-only solution is relatively ...
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### Is destratification ventilation more efficient at ceiling level?

This question is more of a practical physics question. In buildings with heating systems, heated air tends to rise and create air temperature stratification - hottest air near the ceiling, coldest air ...
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### Can conduction alone cause thermal equilibrium?

From the little I know about physics and conduction specifically, it seems to be that a system in which the heat transfer is done solely by conduction, cannot reach thermal equilibrium. I'll preface ...
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### What does this assumption mean in heat exchanger analysis?

I'm studying heat transfer at graduate level, and in the process of deriving LMTD of a heat exchanger, the book took the following assumption : Any axial heat conduction will be neglected. What that ...
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### 'Convective' Fourier number

I'm working with a numerical solution to a 1D advection-diffusion equation for a multiphase problem, with convective exchange between the gas and solid phase. A non-dimensional parameter which comes ...
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### Entropy Change in Radiation and Convection

When a system loses it's internal thermal energy by emitting radiation or by convection what is change of the systems entropy mathematically? I saw this question's answers for radiation only but still ...
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### Is this value of Critical Reynolds Number also valid for non circular ducts?

The flow remains laminar in case of internal flow through pipes up to a Reynolds number of 2300, for most practical cases. Is this value valid only for circular pipes or even for non circular ducts?
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### Does the convective heat transfer coefficient depend on temperature difference?

Consider a flat plate at a higher temperature than the fluid which is flowing over it, with some velocity. Forced convection is taking place. I'm convinced that the value of heat transfer coefficient ...
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### If air is a bad conductor, how does fire heat up a room?

If air is a bad heat conductor, how does fire heat up a room? Could someone help me, as I really don't get this?
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### Rayleigh number for long slit heated at the end

The Rayleigh number is generally described as distinguishing between the convective and coductive regime of heat flow in a fluid. I'm looking at a specific geometry. and it's not clear to me precisely ...
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### Heat Transfer on boiling water

Let's say I'll boil water on the stove from 25°C to 100°C, what heat transfer happens? Is it conduction (heat warms up the pot), or is it convection (causes water molecules to move away from the ...
1 vote
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### Is there convection between two volumes of air at different temperatures?

As I have learned in my engineering classes convection takes place when a fluid meets a surface of both different temperatures. My question: can this also be evaluated for two volumes of air at ...
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### Why do we consider the normal component of velocity in a flux and not the original direction of velocity?

Below is the equation of convective flux of an arbitrary property that is carried by particles. When particles move they carry their property along with them. Given a fixed surface in space, in order ...
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### What is the temperature profile of hot and cold fluids for a double pipe parallel flow heat exchanger?

In books, they just mention the temperature profile is exponential. Can someone help me come up with the exact temperature profile (the relation) for the hot and cold fluids in a double pipe parallel ...
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### Is it wrong to derive Log mean temperature difference (LMTD) of a Heat Exchanger, this way?

I tried deriving the LMTD of a parallel flow double pipe heat exchanger by first finding the temperature profiles of the hot and cold fluid and then averaging them over the entire length of the Heat ...
1 vote