Hello Everyone,
I am trying to apply the convective heat flux i.e., -n.q= h(T_ext-T) where "q"=-k ∇ T
So, If my geometry is selcted as "Form Union(fin)", I cannot select the boundary as shown in the attached figure.
But when I select the geomtery as "Form Assembly(fin)", I can select the corresponding boundary but then gaussian heat source couldn't apply on it.
Can anyone please help ?
Regards,
Akash Meena
The line that you indicated doesn't seems to be an external boundary of your compotation domain, but rather a transition between two materials. For this reason it is not possible to apply a heat flux boundary condition there. Boundary conditions apply only to boundaries.
Leander is very true on his answer, you are trying to apply an external Robin boundary condition to an internal boundary... If you need to do something similar you need to do a different thing, likely using a weak form to define an equation like the one in the boundary condition where the -n.q= h(T1-T2) is the nodal temperatures at each side of the boundary, T1 temperature at the left, T1 temperature at the right, and also the -nq is applied to the left and right sides of the boundary with its right materials, that is a very weird formulation, to be honest, and I do not think it is even well possed (I think it is just wrong...)... are you sure you want to do that???
Javad Aminian-Dehkordi
: I am trying to simulate laser keyhole welding process and was trying to apply the heat flux according to the atached picture. Although I have applied now to the outer boundaries.Leander Boer : Thank you. Yes, you are right. I have applied it to the outer boundaries only.
J. Anaya : I am not sure. Just want to apply the boundary conditiosn shown in the paper as you can see the attched picture.
Javad Aminian-Dehkordi
: Above part is for vapour region. I have to define it because of the level set method to track the the interface.I got two questions::
(1) do I need to define convective heat flux and radiation on vapour region boundaries ? I have named all the boundaries in the attached figure. Please check and you can answer by using it.
(2) Vapour region is gaseous region. It Should be transparent and I should be able to select this in between boundary (1st boundary in the picture). Or it doesn’t work like this ??
J. Anaya Leander Boer : If you can comment on these, please comment.
Thank You.
Dear Javad,
You have described there a very common conjugate heat transfer problem. Basically you need to couple two different physics there, one for the solid domains (Fourier equation) and another for the gas/liquid phase, which is fluid dynamics. The problem is actually a bit more complex if you want to include the melting pool. Anyway, the transference of energy between solid and gas is determined by the coupling between fluid flow and heat transfer, so you do not need to include convection as a boundary condition because it is implicit in the physics you are solving. You can simplify that by not including the gas domain and assuming a given heat transfer coefficient in that boundary: nq=h(T-Text). If you decide to include the gas domains then you do not need to apply the radiation and convection to the gas domains, it actually makes no physical sense. That domain is either quasi infinite (open walls) or in contact with solid walls, i.e. you need to include the interchange of energy with those walls (it can be simplified as a constant temperature at wall, or include the walls explicitly in your conjugate heat transfer model).
Kind regards,
Julian
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