While simulating fluids using CFD tools on 2D / planar mesh and 3D / volume mesh the flow will differ according to the cross-section obviously. In case of a flow mixing simulation, if the cross-section of both channel is rectangle a planar mesh solution gives similar result to a 3D mesh, whereas if the channel is of any other cross-section the flow physics shall vary.
Attachments show analysis result of 2D and 3D mesh of a flow mixing with similar boundary conditions and meshing setup.
What is the criteria for choosing in between 2D and 3D mesh?
Do the analyses which used the 2D mesh strictly adhere to itself rather than a general setup?
It depends on many parameters, besides the geometry of course.
The first thing I would recall is turbulence. Mixing and more generally diffusion phenomena are never purely 2D. If you are in turbulent conditions and you are using RANS models, 3D diffusion might be accounted for by the transport equation of your turbulence quantities. If you are under laminar conditions, then everything depends on you geometry.
In your case, is the aspect ratio of your geometry sufficiently large (say above 50) ? If that is the case then there should not be much difference. You can consider a 2D simulation as a 3D simulation in which the third dimension is much larger than any other dimension.
Computational cost (size of your mesh) and required accuracy are then the two things that should guide you in the decision between the two approaches
Hi
2D CFD flow simulation can not give accurate result as a 3D simulation,exactly.
but their result can be Similar with together, nearly.
nota bene that you can use 2D simulation instead of 3ِD when your Geometry is simultaneous, If your Geometry is not simultaneous, you can not take similar results 2D and 3D.
For example, Geometry is Ogee spillway with thickness 1 m, so you can Regardless of thickness and simulation 2D. that results of 2D and 3D are similar. but if your Geometry is channel, you can not use 2D simulation instead of 3D. because flow is different
Conditions in depth.
any time, 2D CFD flow simulation can not give accurate result as a 3D simulation,exactly.
Good Luck!
Thanks alot
Mendez : Analytical geometry is not too much deep (not bigger than the breadth of the geometry), I think the problem is the mass flux calculation is wrong as Abdul Aziz suggested. I assumed the mass flux of a rectangular slot for 2D and discrete holes in 3D also the hole geometries are circular, mass flux correction may correct the problem.
Souroush: Thanks for the suggestion, I will re calculate and check.
Aziz: Thank you
It depends upon the side cross-section if same is extended in the 3rd direction and of course Aspect ratio.
We recently discussed this in Article Three-dimensional flow structures in X-shaped junctions: Eff...
for a flow in X junture. It not only depends on the aspect ratio, the geometry itself is important.- Badges
- Science topic