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Why the results are different so much by tow modelling methods in simulating the temperature field of laser-remelting
Posted Mar 28, 2011, 11:19 p.m. EDT Mesh, Modeling Tools & Definitions, Parameters, Variables, & Functions, Studies & Solvers 1 Reply
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Dear Ivar
Now, I am simulating the temperature field of laser-remelting. Two methods are adopted to realize the heat source moving:
1) the center coordinate of the laser spot is a function of time, and a constant heat flux is added on the laser spot area. Say, (X0, Y0) denotes the center of laser spot and r the redius of laser spot, a constant heat flux is added on the surface area of sqrt((x-X0)^2+(y-Y0)^2)<=r.
2)fix the coordinate in the center of laser spot and add the moving velocity into the PDE, heat flux is added on a fixed circle area with redius of r.
The same parameters and meshing was setted. However, the results was very different with each other. The spot center temperature of method 1) is far lower than the one of method 2) and the temperature field in spot is not smooth. Meanwhile, the result of method 1) is affected by the mesh size.
May be, the node number in the spot area is the reason? I don't know why. And how to resolve the problem in method 1)?
Please give me some help.
Now, I am simulating the temperature field of laser-remelting. Two methods are adopted to realize the heat source moving:
1) the center coordinate of the laser spot is a function of time, and a constant heat flux is added on the laser spot area. Say, (X0, Y0) denotes the center of laser spot and r the redius of laser spot, a constant heat flux is added on the surface area of sqrt((x-X0)^2+(y-Y0)^2)<=r.
2)fix the coordinate in the center of laser spot and add the moving velocity into the PDE, heat flux is added on a fixed circle area with redius of r.
The same parameters and meshing was setted. However, the results was very different with each other. The spot center temperature of method 1) is far lower than the one of method 2) and the temperature field in spot is not smooth. Meanwhile, the result of method 1) is affected by the mesh size.
May be, the node number in the spot area is the reason? I don't know why. And how to resolve the problem in method 1)?
Please give me some help.
1 Reply Last Post Mar 29, 2011, 2:19 a.m. EDT
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Posted:
1 decade ago
Hi
I'm not sure I catch everything, but its is clear (for me) that when you apply a heat source as a Gaussian area source, it is distributed onto the underlaying mesh, just as with waves, you need to have a reasonable number of mesh elements per spot area (quadratic => >10 I would say) to resolve it correctly, otherwise you will have sampling errors getting rather large.
Then when you apply a time transience analysis you need to have a time sequence (and to enforce intermediate or strict stepping) that is fine enough to simulate the constant power moving around, else you will get stippled hot spots, I believe
--
Good luck
Ivar
I'm not sure I catch everything, but its is clear (for me) that when you apply a heat source as a Gaussian area source, it is distributed onto the underlaying mesh, just as with waves, you need to have a reasonable number of mesh elements per spot area (quadratic => >10 I would say) to resolve it correctly, otherwise you will have sampling errors getting rather large.
Then when you apply a time transience analysis you need to have a time sequence (and to enforce intermediate or strict stepping) that is fine enough to simulate the constant power moving around, else you will get stippled hot spots, I believe
--
Good luck
Ivar