Ivar KJELBERG
                                                                                                                                                    COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
                                                         
                            
                         
                                                
    
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                                                Posted:
                            
                                1 decade ago                            
                            
                                Aug 25, 2015, 2:47 p.m. EDT                            
                        
                        
                                                    Hi
there is no 1:1 rule there. You need a reasonable mesh quality to get "good" results, but thereafter, the mesh density does not result into any "linear increase in precision". This is really very model dependent. Furthermore, COMSOL is set up such that the "default" mesh quality is mostly adequate to get to "good" results.
So what are "good" results ? 
a few decades ago 10-20% concordance with measurements were considered perfect, today we are more at 1%, often better, but mostly we do not have precise enough material data or true BC load conditions to be able to get results far better than 1:100 or there-around.
Anyhow a FEM model is just a simplified representation of reality, do not expect too much. Still its great to learn physics and very helpful to dimension complex systems :) 
--
Good luck
Ivar                                                
                                                
                            Hi
there is no 1:1 rule there. You need a reasonable mesh quality to get "good" results, but thereafter, the mesh density does not result into any "linear increase in precision". This is really very model dependent. Furthermore, COMSOL is set up such that the "default" mesh quality is mostly adequate to get to "good" results.
So what are "good" results ? 
a few decades ago 10-20% concordance with measurements were considered perfect, today we are more at 1%, often better, but mostly we do not have precise enough material data or true BC load conditions to be able to get results far better than 1:100 or there-around.
Anyhow a FEM model is just a simplified representation of reality, do not expect too much. Still its great to learn physics and very helpful to dimension complex systems :) 
--
Good luck
Ivar                        
                                                
                                                                                                            
                                             
                        
                        
                                                
    
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                                                Posted:
                            
                                1 decade ago                            
                            
                                Aug 25, 2015, 11:49 p.m. EDT                            
                        
                        
                                                    WOW, Thank you.. thank you very much sir, for your quick response. @Ivar                                                
                                                
                            WOW, Thank you.. thank you very much sir, for your quick response. @Ivar