# Questions tagged [convection]

transport mechanism involving bulk motion of a medium

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### Calculating temperature change out of a room [closed]

Currently I'm trying to find how the outside temperature affects the internal temperature of a room through its walls. I'm trying to use the convection heat transfer equation to find the exterior wall ...
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### If I'm inside water, is the amount of heat energy I can receive capped because water can't go above 100°C?

I just learned about double-boiling, where instead of putting a pot directly on the flame stove (where it can get too hot), you put a big tub of water on the flame, and put the pot in the tub of water....
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### The roles of convection and advection in the absolute flux for species $i$ in mass transfer

I am confused as I have been reading on mass transport on multiple sources and they seem to use "advection" and "convection" interchangeably in the equation for the absolute flux ...
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### Lumped body analysis

$k$ - thermal conductivity, $h$ - heat transfer coefficient, $\rho C_p$ - Volumetric heat capacity, $T$ - temperature $T_\infty$ - Temperature of exposed cooling surrounding environment Consider two ...
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### At what circumstances is Nusselt's theory of evaporating falling films valid?

Nusselt's theory of evaporating falling films assumes no convection and neglects the effect of inertia. At what circumstances is that valid? Any books or articles that discuss this in depth would be ...
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### Explain how convection is a type of heat transfer

So, from my understanding convection is when a gas or liquid is unevenly heated and the warmer portion rises, as it is less dense, and the cooler portion sinks creating a cycle(something along those ...
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### How does the height of the hole on the bottle affect the burning time of the candles?

We took 3 identical bottles and drilled some holes on the side, each bottle had a hole but at different heights. Then we covered the burning candles with the 3 bottles and measured the burning time. ...
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### Conduction in liquid and gas

Is this condition correct, "if liquid and gas heated from top, then it will be possible for 'conduction' to occur" ? One reason i can think is : when liquid or gas is heated from sideways or ...
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### What creates the Global Dipole Magnetic Field in the Sun?

I understand that the Sun undergoes convection and with rotation, the convective cells have a helical motion because of the Coriolis Force. My confusion comes from the fact that via the right-hand ...
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### How to measure actual conductive & convective losses inside an enclosed container?

I've been studying convection and come across empirically-derived formulas for calculating the Nusselt number for various geometries. For my particular use case, I'd like to measure the actual ...
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### How do I calculate the rate of heat loss from an enclosure when I have a plot of temperature vs time and the enclosure's material details? [closed]

I have an enclosure running an ON/ OFF temperature control system. The below graph shows internal air temperature over time. I have the raw data providing actual values. I have the dimensions of the ...
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### How to determine air flow required? [closed]

I am making a sound dampening box for a vacuum pump. It’s loud almost 96dB. I have an ultra quiet fan to vent heat out of the box. I want to calculate how to make a couple small inlet holes while ...
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### Can land breezes be an example of perpetual motion?

Since perpetual motion refers to a never-ending motion with no external energy provided whatsoever, can land breezes or sea breezes be an example? Or perhaps even trade winds, since this, I believe, ...
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### Rigorous definition of convective heat transfer

Through all textbooks I've come across, convective heat transfer is traditionally defined along the line of "[...] a process by which heat is transferred by movement of a heated fluid such as air ...
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### Local and convective acceleration in 'water tank-pipe' systems

I found this elegant solution to the Euler equation when the classic 'water tank-pipe' system opens the valve - the initial unsteady flow "stabilizes" and the equation turns into the ...
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### Why does a stream of smoke interact with a light source?

The photo in the top row shows the stages of interaction of a stream of smoke that is formed from a smoking stick with a light source. The light source turns on at the moment when the smoke rises ...
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### Convection in stratified atmosphere

In the stability analysis of stratified atmosphere in the presence of gravity, we consider a blob of atmosphere and perturb it (move it up by a small height $\Delta z$). Initially, the blob had the ...
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In star convection you can work with radiative and adiabatic temperature gradients, that for example the radiative one can be defined as, $$\nabla_{rad}=\frac{3\kappa L P}{16 \pi a c G m T^4}$$ This ...
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### Velocity field of a fluid in a porous pipe

Consider the situation of the image: A fluid is passing through an infinitely long two dimensional pipe, with a hole in it (form L to L+a). Clearly some fluid will be ejected out from that hole. Now, ...
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### Adiabatic equation of state for a star

I am a little confused. To describe stars the adiabatic equation is often used: P = k$\rho^{\gamma}$. For a monatomic gas, the following holds: $\gamma = \frac{5}{3}$. However, since the sun is not ...
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### If you moved your hand continuously through fire, would it feel hot?

If you quickly pass your finger or hand through a candle or fire, it doesn't feel very hot (great party trick). Is this because your hand spends such little time in the fire that there isn't enough ...
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### Building a house that is warm in winter and cool in summer [closed]

The Northern house architecture is strikingly different from that used in the South (I am not taking extreme cases, thinking more of Northern or Germany versus Mediterranean: Thick layers of thermal ...
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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 ...