I have a 3d solution dataset on a surface of the sphere (eg for Potential distribution, V) from which I can visualize a boolean expression plotting a 3d surface (not volume ! ) where a condition is true (eg V>=some value). I wish to find the surface area where that boolean condition is true. Please describe how it can be done.
Results-Derived Values-Surface Integration, set Expression equal to 1 to get the full area, and Expression equal to (u>1.5) to find the area where u is larger than 1.5.
Thanks Christensen, it worked. I am new to Comsol.
So, the complete expression in surface integration will be 1*(V>1.5)
Well yes, or rather two expression 1) 1 and 2) V>1.5. You don't need 1) if you already know the total surface. You could then afterwards calculate 2)/1) to get the ratio, so 0.4 would mean 40 % of the surface has V>1.5.
@ Christensen, Just bothering one more time, I see its fairly simple to export the 3d coordinates of that boolean surface out of COMSOL but I was unable to find a way to feedback the 3d coordinates within COMSOL using variables. I am sure, it can be done but I would really appreciate if you could point me to the correct builtin function for that which extracts the coordinates.
Hi Danish. The question for some reason disappeared, I thought you had deleted it. But now I can see that you had one more question. I am not entirely sure what you want to do, though? You want to extract some coordinates after having run a simulation, and then apply those back into a simulation?
Hi Rene, I never deleted it, its gonna be useful for others too. Regarding the second question, what i want to do is to modify material properties based on a boolean logic on the 3d surface as described above but in a dynamic simulation that includes structural deformation. So, if its a static study, then exporting the data is the way to go but in a dynamic study with deformable shapes I need to feedback the info during intermediate steps.
But that becomes cyclical, doesn't it? The displacement depends on the material values, so if you try to have the displacement depend on material parameters, with material parameters that have to depend on displacement, for example, then the solver can find no solution.
Not really since, the electric potential is expected to change in the new deformed configuration with new material properties, so cyclic only in terms of the computational process but not in physical dynamics, I hope
Ah okay. So one physics determines the deformation, and the other just follows along, but you need to update the material values based on that. But does that not mean that you simply have to set up a coupling? It may already be available. Or is it truly the MATERIAL values you want to change? Why do they change?
Yes, I do understand it is in the coupling variables which is already there somewhere in COMSOL but the docs and tuts i searched so far are not enlightening me. The material values change because they are functions and not constant (eg. stress dependent elasticity etc)
Alright, then you need material non-linearity. It is a module on its own, but you may be able to hack it somehow. Maybe search on comsol.com/blogs for material non-linearity...
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