# Questions tagged [convection]

transport mechanism involving bulk motion of a medium

194 questions
Filter by
Sorted by
Tagged with
1answer
52 views

### 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 ...
0answers
14 views

### Convection current vs current created by an electromotive force acting on a charge

I am wondering if I can use the term 'convection current' for the current created by an electromotive force acting on a charge that sits on some rod that moves through a magnetic field. The convection ...
1answer
62 views

### 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 ...
1answer
39 views

### 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 ...
1answer
42 views

### 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 ...
0answers
22 views

### 1D Convective Heat Transfer

I am considering 1D convective heat transfer in a vertical heat pipe with a constant wall temperature Tw, with z varying from 0 to L. Applying the Boussinesq assumption, we arrive at the following ...
1answer
29 views

### 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 ...
1answer
58 views

### 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 ...
1answer
34 views

### While determining LMTD for a heat exchanger do we assume, the tube wall to be at a constant temperature (no variation along radial direction)?

The derivation of Log Mean Temperature Difference (LMTD) for a Heat exchanger at preliminary level makes some assumptions like, constant specific heats, steady state operation, no changes in kinetic ...
1answer
18 views

### Intuitive explanation of convection in a closed volume

I am trying to wrap my head around what happens when say a hollow cylinder containing a gas is heated from the bottom. Intuitively I know that the gas in the cylinder will heat up, expand and pressure ...
0answers
18 views

### Thermal Boundary Layer

When we study convection in Heat Transfer then there a part where a fluid flows over a plate maintained at a temperature T. In this case heat transfer ocurrs both by conduction as well as convection ...
0answers
67 views

### What is the ideal gap between two panes of glass for insulation? [closed]

I have two panes of glass, about a 3/8" thick (.95 cm). Space efficiency and aesthetics ignored, how far apart should they be spaced to maximize heat insulation, assuming the gap contains regular ...
2answers
27 views

### Why is the rate of energy conducted in a rod equals the rate of energy released from the surface at the other end?

Assuming energy is released as convection only,we always do questions by equalizing, $$P_{\text{conducting}} = Q/t = KA (T1 - T2)/L = eA(dT).$$ Assume the system is at Steady State. Why does this ...
0answers
27 views

### Why does bologna inflate radially when on stove?

I noticed that when heating up bologna in any way it inflates at the center, while other stuff tends to let the air escape sideways, or inflates in different places, like an egg or sausage. Nothing so ...
1answer
53 views

0answers
135 views

### Heat Generation in Watts per cubic meter - how to apply this to a volume?

Water is running through a pipe. The pipe is heated uniformly in order to heat the water running through the pipe. I want to calculate how much heat needs to be generated by the pipe in order to heat ...
0answers
27 views

### How does the speed/rate of convection currents in water in a tube affect the change to temperature of water at the upper end of the tube?

I have done some experiments in which I heated a burette filled with water by applying a preheated soldering iron to approximately the middle of the burette and measured how the temperature of water ...
0answers
9 views

### Convection/conduction simulation run from equal temp, but losing heat

I was investigating the effects of heated wall materials on outdoor air temperature and indoor air temperature with a certain software. The system is as the following: 1x1x1 meter cube of outdoor air ...
0answers
32 views

### Hypothetical: generating an inadvertent and transient magnetic field in a massive biodome

I am doing a thought experiment for a sci-fi novel and have a physics related question. I do have some elementary knowledge of physics from college. Before I ask my question, I need to establish a ...
0answers
34 views

### Can one model fluid flow only by using the convection–diffusion equation?

Modeling fluid flow in a coil seems very complicated, especially for turbulent flow. Having Navier-Stokes equations seems to be the right way to go, but I was wondering... can one use the convection-...
0answers
71 views

1answer
65 views

### Are there no convection currents in ice-boxes and aerogel?

Technologies dealt with Ice-boxes have been used for a long time to prevent ice from melting for a longer time than keeping it in open. Aerogel is still an emerging technology (I came across it on ...
3answers
156 views

### From kinetic theory - why does heat rise?

I know the explanation from fluid elements and densities however I don't find it satisfying. Is there an explanation from kinetic theory?
2answers
132 views

### Density of ice < water?

In the situation of an ice cube placed in water and eventually melting, it is supposed that natural convection is the process in which heat transfer from water to ice occurs. However, natural ...
1answer
117 views

### What is oscillatory convection?

I come across this term in a lot of papers which talk about convection and instabilities but could not find a proper explanation of what oscillatory convection is. Is it the fluid which is oscillating ...
2answers
284 views

### Does the Boussinesq approximation imply 'incompressible' flow?

Does the Boussinesq approximation imply that compressible inertial effects in the flow can be neglected (i.e. density can otherwise be treated as constant)? It seems that it must be the case and ...
0answers
101 views

### How much conduction, radiation and convection influence in a thermos flask?

It has been thoroughly repeated that thermos flasks prevent heat loss by minimizing heat conduction, radiation and convection from the bottle to its ambient. This has been answered in this SE. However,...