Co-simulating - Temperature analysis

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Co-simulating - Temperature analysis

cassianozago
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Hello

I simulated a interaction between an air layer (12 cm) and a concrete plate (12 cm). My doubt is:

1) The temperature gradient between the top face and the bottom face, of the air layer, shouldn't be smaller, after 75 minutes? (see Annex 1). I am finding a difference of 900 degrees.

I think, after a time, this air layer should have the same temperature, in top and the bottom faces. I expect to see it.



Boundary condition utilized in Air Layer:

- Inlet: Temperature = Furnace (see Amplitude)

- Outlet: Pressure = 0

- Co-simulation = Interface between air layer and concrete plate



Abaqus File (Plate.CAE): Plate.cae 

Abaqus File (Plate.JNL): Plate.jnl


Problem:



Annex 1 - AIR LAYER results:
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Re: Co-simulating - Temperature analysis

rpabloa
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your simulation looks good. In the stationary state the temperature never are the same.
maybe need to check the air's difusivity . or thermal constants for concrete.
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Re: Co-simulating - Temperature analysis

cassianozago
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Hello rpabloa

I'm using Transient analysis, because the temperature varies with time (see fire curve ISO834). The properties (and units) are correct and vary also with the temperature (according EUROCODE 2 Design of concrete structures - Part 1-2 General rules - Structural fire design).

About Diffusity. How do I do to define it when I'm doing thermal analysis? Do I define only in air layer?

Best regards
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Re: Co-simulating - Temperature analysis

rpabloa
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thermal diffusivity = (thermal conductivity)/(heat capacity), for the air and concrete.
but, sure you has been used,
check this, ThermalDiffusionLength= sqrtl( thermal-diffusivity / (PI*frequency) ) must be grater than the air layer.
you can estimate frequency for the experimental fire curves.
Finally, i guess that you will no reach the same temperature in this simulation, due to your boundary conditions.