In Heat Transfer in Solids

Doubts in COMSOL SOFTWARE

Here you will find the list of what I would like that you could teach to me, or we could talk about:

1. Application Builder (It can be a very basic model or use that one that I sent to you), because Maria Parviainen told me that this could be useful for us, since we have few licenses.

2. Is possible to calculate the distance that an object flies when falls from a high of 100m! Or is possible to know what are the wind forces applied in the object.

3. In programming If, Else If, … there is AND and OR? I tested only an example from tutorial “IF a+b>20” and it worked. But I mean there is a language like “IF a>20 AND b>20”. Or Could you tell me what kind of functions I can use here?

Manuel Martins Page 1 of 14


HEAT TRANSFER

In heat transfer my focus now is trying to know how the heat goes throw 2 materials like in Insulation+steel plate+insulation plate file. And all cases I am working now are time dependent.

Big issues is get results that could be realistic, because when a plate has initial temperature value 20C and after get fire it stays minus degrees it can´t be too realistic.



This (Left figures) is same model that I sent to Jukka Tarvo. A model that has insulation in contact with 2 different materials. I would like to ask how it could be the calculation if there is a gap of air between insulation and the plates(right figures)

Should I choose Heat transfer in solids or Conjugate heat transfer?

Do I need to draw a box (air) when is natural ventilation.

If we choose heat transfer what is the difference between choose laminar or turbulent, because in my idea air in beginning (20 C) can be laminar, but when

it begins warmer it will be turbulent. Should I choose turbulent?



In what we will need another heat transfer in solids??

If we have Air it should be insert Heat transfer in fluids. Comsol needs to “know” if our model is surrounded by the air? For example in next case?

Used when there is a heat generation that warms the surround or something specify.

In what case we should use this. Outflow reminds me to wind.

What is the difference between, Inflow heat flux and heat flux?

What is the difference between Boundary Heat Source and heat source?

Where or when we can use Pairs?



In heat transfer in solids:

How we should choose equation form? Study controlled, stationary or time dependent? My doubt here is because when we choose the study its already chosen Time dependent.

What I need to do after fill the boxes in Physical Model?

If I choose a surface-to-surface radiation what that means? Is the same thing if I choose this box between to solid materials or between a solid and a fluid (air)? What is the difference between heat transfer with surface to surface radiation in Add Physics (see in next page the picture)?

What means the others?

If I have an insulation wall made by wool, should I calculate it with heat transfer in porous media?

What means this variable T in Dependent variables?





In Heat flux in Fire the variable Text, External temperature is chosen temperature of fire, Tfire. But in heat flux at 20C what temperature should be chosen? Tfire, because that temperature won´t be constant (always 293.15K) during the fire time.

In Heat flux in Fire the variable Text, External temperature is chosen temperature of fire, Tfire. But in heat flux at 20C what temperature should be chosen? Tfire, because that temperature won´t be constant (always 293.15K) during the fire time.



I believe that if our box in surface to surface radiation is filled, one of the things that needs to be input is diffuse Surface with fire. Where ambient Temperature is temperature of fire.

And How about the surfaces that doesn´t have fire (grey surfaces), that in initial conditions are at 20C? Should we insert a diffuse surface too? What temperature should be inserted?

And the surfaces (red) that are in contact? Do we need to insert any input?



In this case of surfaces in contact should we use Thermal contact? What cases is possible to use Thermal contact?



In mesh I would like to understand what makes this size? I understand when Size is under Free Tetrahedral for example.

What are the differences between this 2 boxes if we do right button of mouse on top of Mesh1?



After calculation is possible to get a list of expressions (Replace Expression) that after plotted can give other properties to your calculation. Is possible to get a list of all expressions? Because is tricky to choose an option, because if we choose the wrong one it needs to make it again all steps to choose.



SOLID MECHANICS

In this section we could use the geometry of column, basically is a composite column where is applied a point load or a surface load.

Stress in reinforcement, stress in pipe, stress in concrete, displacement, cross section properties, buckling, thermal expansion are properties that for example I would like to know.

For example if is a beam I would like to know deflection of beam. Is possible to create or parameterize some sections? For example in steel construction we have HEA 100, HEA 120, …..HEB 100, HEB 120,… is possible to have a library of this cross sections like you have a materials library?

Bolt pre tension how it works??

What is the difference between Truss Interface and Beam interface?



How to solve problems like this, in material? I deleted the other stuff that I had and I went to apply materials and all materials are applied. Edges????




Date post:	04-Jan-2016
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In Heat Transfer in Solids

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