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moving coordinates.

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Hey foks,plz help me with this.

I am modelling a moving volumetric heat source.I want to move my coordinate system with the heat source..

Say the heat source is moving along z-direction.Then I woud like to define me z'=z-V*t.

Please help me with any inputs.

Thank you.

1 Reply Last Post 14 nov. 2009, 09:12 UTC−5
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)

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Posted: 1 decade ago 14 nov. 2009, 09:12 UTC−5
Hi

I would say there are different ways, depending on what you want to use it for.
From my knowledge the "cordinate system" you might define in COMSOL (still rather primitive in V3.5a) are static and define once in the same way as Constants, except for the deformed frame ones in structural used for follower loads, which are linked to the deformations.

But if you want to trace something you can alwas define a function zz(t)=z+Vw*t (note avoid conflicts with classical Comsol names, u,v,w is normal the displacement along "x,y respectively z" or parts of the strain tensor), and then use zz in the postprocessing, provided "t" is defined, it's that simple.

But, I suspect you wanted more.

If you are rather new to COMSOL, then I can also suggest to read through the documenation a couple of times, I know it long and tedious, and quite dense, but COMSOL in contrary to "classical and older" FEM programmes is providing "all physics" and not just an excerb, readily normalised, for one type of engineering.
This means that you have to think more and really understand the tool and what you are doing, but once over this stage, you really appreciate it, and you ask yourself why you used those old fashoned, single track tools, before.

Good luck
Ivar
Hi I would say there are different ways, depending on what you want to use it for. From my knowledge the "cordinate system" you might define in COMSOL (still rather primitive in V3.5a) are static and define once in the same way as Constants, except for the deformed frame ones in structural used for follower loads, which are linked to the deformations. But if you want to trace something you can alwas define a function zz(t)=z+Vw*t (note avoid conflicts with classical Comsol names, u,v,w is normal the displacement along "x,y respectively z" or parts of the strain tensor), and then use zz in the postprocessing, provided "t" is defined, it's that simple. But, I suspect you wanted more. If you are rather new to COMSOL, then I can also suggest to read through the documenation a couple of times, I know it long and tedious, and quite dense, but COMSOL in contrary to "classical and older" FEM programmes is providing "all physics" and not just an excerb, readily normalised, for one type of engineering. This means that you have to think more and really understand the tool and what you are doing, but once over this stage, you really appreciate it, and you ask yourself why you used those old fashoned, single track tools, before. Good luck Ivar

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