I'm running simulation both 2D and 3D of the same geometry.The thing is,i got both result not same but i have read somewhere that 3D result is more accurate than 2D result.
Can anyone explain how to justify that 3D result is more accurate than 2D.
thanks
Perhaps accuracy is not the best word. I would rather say that 3D simulations are more realistic than 2D simulations. It may be expected that the middle layer of added third dimension is quite similiar to what is obtained from 2D simulations, but not necessarily to the outer layers of 3D picture.
Perhaps accuracy is not the best word. I would rather say that 3D simulations are more realistic than 2D simulations. It may be expected that the middle layer of added third dimension is quite similiar to what is obtained from 2D simulations, but not necessarily to the outer layers of 3D picture.
Usually 3D simulations are more realistic that 2D because they can capture gradients along the 3d direction that in 2D concept is assumed to be infinitely extended.
Differences may arise because of the following aspects:
- different meshing procedure and elements used;
- different boundary conditions (3D allows for more realistic BCs);
- assimetries unable to be caught in a 2D domain;
The computational burden related to a 3D simulation is higher but for sophisticated systems it is the only way to ensure realistic results.
You mustnote also that when performing both 2D and 3D runs, you should work under no mesh - sensitivity calculations meaning that you have to refine your mesh to such an extent that your results are not depending on its quality. Only under this condition you can make a comparison between 2D and 3D results.
You should identify the directions of spatial gradients of the variables under interest in your domain and then make decision whether a 2D or 3D simulation is required. If a quantity is not changing in a specific direction then you can neglect that dimension and opt for 2D.
I agree with aziz that in 2D computations you assume values of important variables. On the contrary in 3D computations you can defined the actual values or you can write the expression for real flow with real values. You have to take care of forces and momentum in all directions and if you defined a non-logical condition, the 3D simulation will be failed.
-faizan
It depends on the problem we solve. In a very long parallel plate geometry one dimensional flow is best. in entry flows with finite dimensions 2d is better. if symmetry is not followed 3d is better.- jv r murthy
It depends to types of products. Some furniture's,electronic,interior and construction company prefer 2D drawing or some small design firm still use 2D software.They prefer 2D because they already get to use it (when they already have cnc use 2D software) and low cost (software price). They also like 2D because it faster than 3D, which you need more technical thinking doing the 3D. Time is important to industry. But when going to product design such like robotic, machine, home appliance (electric product), toys, and transport design should use 3D software. For me it depends but we should competent 2D and 3D and have understand the fundamental engineering drawing.They is no shortcut to competence in this area.
3D modelling places no constraints on the deformation of the structure and all the deformations of the structure can be simulated with proper modelling but 2D modelling assumes the model to be rigid in some sense. For example, the shell elements assume that the section cannot deform at all ( ie the section is rigid) along the thickness direction. In addition, it assumes that the strain varies linearly along the thickness at any point in the element. These assumptions are valid to a good degree of accuracy only under certain conditions. Suppose, the deformation of section is required to be simulated, these shell element model would fail. But 3D element model can simulate that. Similar problems exist with the plane stress, plane strain and axisymmetric elements.
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