How to have interaction across meshes?

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  • Last Post 15 February 2019
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SaurabhDas posted this 13 February 2019

I am doing a FLUENT simulation wherein I flow a jet of nitrogen over a block at room temperature. Expected results is that the block(which is at 300 K) will cool down after a period of 1 s.

However, this is the result:

The block is not changing temperature at all. I feel like I am missing something here.Maybe a way to link both bodies?

Could anyone please help me on this? Thank you.

 

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abenhadj posted this 13 February 2019

Can you share a screenshot of boundary conditions and cell zone conditions?

Best regards,

Amine

SaurabhDas posted this 13 February 2019

Oh yes of course!

Here are the boundary conditions:

I only changed the left outer and the right outer boundaries:

The rest of the boundary conditions are untouched.

Here are the cell zone conditions, btw:

abenhadj posted this 13 February 2019

So the inner body is declared as solid domain. Is this correct? Which source terms are you providing?

Best regards,

Amine

kkanade posted this 14 February 2019

i am not sure if i got the question correctly. 

but can you please use non conformal mesh between inner and outer domain. 

the best way is to get conformal mesh. for that you will need to use share topology at geometry level. 

 

SaurabhDas posted this 14 February 2019

The inner body is defined as fluid as I wanted to see how much faster molten steel would solidify under forced convection, There's no source term though, I have checked that box ,but I have not put any source terms.

SaurabhDas posted this 14 February 2019

I used 'Share Topology' and joined the interior and exterior using 'Form New Part'. Then I made the cell zones by using named selection.

I also managed to create wall shadows. Now how should I proceed?

rwoolhou posted this 14 February 2019

Can you replot to include the walls & show node values only for temperature? Also plot velocity contours. 

As an aside, steel will be very solid at 300K.

abenhadj posted this 14 February 2019

So if it is fluid so you have coupled walls? Are you solidification and Melting Model?

Best regards,

Amine

SaurabhDas posted this 14 February 2019

Oh yes I know steel would be solid at 300 K, I just wanted to figure out how to get the heat from a body leached out by a continuous flow of air. The air is at a lower temperature by the way. If I figured out this step, I could move on to the solidifcation/melting part.

And for some reason, the original file got corrupted so I had to start afresh..

Domain: 

The cell zones and boundary conditions: (essentially the same as the original)

 

Temperature contours: (Some irregularities but I am sure thats due to the coarse mesh.) 

Velocity vectors: 

SaurabhDas posted this 14 February 2019

Yes, the walls are all coupled, and I am using the solidification and melting model, but there's no solidification or melting involved, yet.

abenhadj posted this 14 February 2019

So you fluid is enclosed by the outer fluid: no Flow no Convection Inside if density Inside is not Temperature dependent.

Best regards,

Amine

SaurabhDas posted this 14 February 2019

Exactly, no mass transfer or flow of any kind is expected as it's still solid at this temperature, but I expect a temperature change because the inlet gas is at 1100 K 110 K. (sorry for the typo)

abenhadj posted this 14 February 2019

Post the material properties of your enclosed fluid. No flow no enhanced transfer which is important for fluids. Add inflation layer at the contact wall.

 

Best regards,

Amine

SaurabhDas posted this 14 February 2019

There you go. And I meant 110 K, not 1100 K. Sorry for the typo.

abenhadj posted this 15 February 2019

Hi if you change the internal fluid to solid then you will see that cooling (steady run with very lrage solid time step). If it remains as fluid you probably needs to run it for a long time or increase the time step. That works for me.

Best regards,

Amine

abenhadj posted this 15 February 2019

You have quite small thermal diffusivity that is why the enormous time required to transfer the heat.

Best regards,

Amine

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