Imagine I have a solid bar and I want to define it as a heat source. The bar is in the middle of a hollow cylinder and air flows inside. Shall I define it as a surface heat source or a volume heat source? Thanks in advance.
I'm far from any sort of expert on this but if the bar is not touching any surface wouldn't it then make it a volume heat source since it is in the centre of the cylinder?
I think it is a good point that you mentioned about "the bar not touching any surface". But it seems that I have to consider other things as well.
what are u trying to model?
I have a cylinder and right in the middle there is a bar. I also have a flow(air) that goes in with a specific temperature and mass flow rate. This is an internal analysis. I want to use this bar as a heat source and investigate the temperature distribution in the cylinder and also in the cylinder wall. Attached is a schematic of the problem.
what's different about this one than the what was in the other thread on this?
It is the same model. Just wonder if I should use surface heat source or volume heat source for the bar.
Depends on your heat rate.
There are three ways to know which one to use:
1- If you have the heat generated per unit of VOLUME (often denoted as q''', W/m^3) the use Volume Heat Source, if you have the heat generated per unit area (often denoted as q'', units of W/m^2) then use Surface Heat Source.
2- If you have the Heat Generation Rate of a Body (denoted as Q, units of W) then user Volume Heat Source, if the Heat is generated at a surface use Surface Heat Source.
3- If you know the temperature of the body, use Volume Heat Source.
Hope this helps.
PD: This is all available at the SolidWorks Flow Simulation Help. Shall you need more information, you should consult it.
I don't have any value for the heat generation. Actually I want to define it and apply it to the bar. So I am not sure which one to use as each of them gives you different results at the end. For example if I use 1000 W as a surface source, it will obviously different from when I use 1000 W as a volume source. I want to know which one is more realistic to use, surface heat source or volume heat source? Thanks.
Depends on the physics of your problem. How is that heat generated in real life? Is the bar conductive and there is a current going through it? Is the bar heated to a certain temperature and is left to cool off? and most importantly, WHERE is the heat generated?
There's is not a definitive answer in the form of "ALWAYS use volume heat source". If that was the case, when you can always apply only on of the two conditions, then it the other condition wouldn't be needed, right?
I'm pretty should that you can answer those question and make the call on your own
Thanks Gian for the reply.
it depends on what the physical situation is that you are approximating.
These kind of replies upsets me. The OP is clearly not sure how and what to do with the flow simulation and is basically trying to learn and get others to guide him in the right direction.
In my opionion, the question was not very unclear. Gian was able to put time and write a useful information based on his experience. Instead, Bill responded three times with no insights, let alone any information regarding the question.
If your answer is, "it depends," why bother replying?
I don't think anyone here was trying to be hostile or malicious. I think they were just trying to more clearly define the problem so as to better answer the question. If we don't know what the simulation is physically trying to represent or have misinterpreted the question, then the contributions of the forum members may be misleading for that specific situation.
Joon Kim wrote: These kind of replies upsets me.
Joon Kim wrote:
These kind of replies upsets me.
You are getting upset about 2 years old post.
Joon Kim wrote:responded with no insights, let alone any information regarding the question.
responded with no insights, let alone any information regarding the question.
Think of the applied heat source integrally instead. The value you apply gets distributed to the surface or volume proportionally. So if you define the surface heat source value to a group of surfaces, then depending on their specific areas, the value gets distributed proportionally by area (and of course it really depends on how the mesh captures the area). Similarly for a volume heat source, the value is distributed proportionally to the volume of the cells inside the solid body(ies). I generally recommend sticking to a Volume Heat Source (Flow Simulation uses a volumetric mesh).
If done correctly in both cases, whether by Surface or Volume source, they should be equivalent.
When you set a heat generated by unit area (W/m2 for a Surface Source) or by volume (W/m3for a Volume Source), you are defining the values to those geometric features directly, meaning not integrally proportional.
I hope that this clears up your question.
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