Learning Forum

[Khodor Sleiman]

Hello, 

I was creating an SLM simulation and when I changed my thermal conductivity from 0.75 to 3, the liquid fraction stopped working and always appeared as 0. I read the solidification/melting theory guide and it seems that the liquid fraction should only depend on the solidus and liquidus temperature, thus, I do not understand how to fix this error, as I don't think the thermal conductivity should affect it. For reference, the temperatures of my simulation did not change much and according to my hand calculations, the material should be melting. 

[Rob]

Can you post some images? If you only changed the conductivity it should just alter the temperature field, but if that then drops the temperature it'll solidify. 

[Khodor Sleiman]

Hi, this is what it looks like when the thermal conductivity is 0.75:

 

and this is what it looks like when the thermal conductivity is 3: 

 

The temperature does drop a bit, but not below the liquidus temperature (1450K), also there are frames where the temperature is 3000K and still the liquid fraction is 0. 

[Rob]

Hard to see what's fluid and what's solid (zone, not frozen). If you replot just the fluid zone temperature with node values off how does it look?  In the second image very little, if any looks to be over 1450K. 

[Khodor Sleiman]

The temperature scale of the second picture is not always consistent, there are times where the temperature is 2000 - 3000K, yet the liquid fraction is still 0. I don't understand what you mean by replotting just the fluid zone temperature with node values off. 

[Rob]

The contour you've shown has significant areas under 700K, so I'd not expect any liquidus fraction there. 

Node values off means we see the cell values. If your mesh is too coarse it's possible the smoothing is showing a misleading result.