[Marci]

I have to simulate several helical coils inside one big cylindrical tank. My knowledge of CFD brings me to start with a 2D model for later move to the 3D.

However, I have two doubts/problems.

1) If I take a cross section of the helical coil itself and analyze the problem, I think that I end up with one symmetric problem. So, I can take whatever section I want and the end results of the simulations should be the same. If I change the cross-section, the only thing that is changing is the position of the crossed circle of the coil. See the image called "Coil symmetry" to have a better idea.

However, the ratio of the coil area to the outside fluid is different in 3D compared to the 2D case. Do you think that increasing the circle area is a good solution to this problem? If yes and if I do that, do you think that the results will still be good even if I am not able to reach the same area ratio of the 3D case?

2) Now, if I take a cross section of the tank, the situation is different from the one mentioned above. I think that the problem is still symmetric, but now for the cylindrical tank and not for the coil. Indeed, for some cross sections I can still have circles in different positions (like the previous case), but the more I reach the outer coil surface, the more this circles change shape. See the image called "Cylinder symmetry" to have a better idea. Do you think that I can do simulations in 2D for such case? If yes, do you think that the results will still be good? If yes, what cross section should I take?

In the end, do you have any advice on how should I perform the 2D simulations? Or do you advise me to start directly with the 3D?