- #1
chengmo
- 9
- 0
How do we solve the geometric coincidence problem? I need a semi-cylinder that fits into the cuboid but if I use the cuboid and the cylinder directly it's geometrically problematic
Can MCNP solve the geometric coincidence issue with a semi-cylinder and cuboid?
- Thread starter chengmo
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- coincidence Geometric Mcnp
In summary, the conversation discusses how to solve a geometric coincidence problem in MCNP, where shapes need to intersect and be defined in a specific way. The conversation also addresses a specific issue with cell definitions and the use of positive and negative surfaces. The issue is eventually resolved by correcting an error in the x-axis, but there is still a problem with cell card 1. There is also mention of a discrepancy between MCNP and VisEd in terms of displaying the model.
- #2
Alex A
Gold Member
- 246
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I'm not quite following the question. MCNP does Constructive Solid Geometry. Shapes are supposed to intersect and then you tell it which volumes are what part of the problem.
- #3
chengmo
- 9
- 0
I set up four cubes but only two are displayed. In my setting, there should be cuboids in the middle and under the ring. Why？
- #4
Alex A
Gold Member
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In a cell definition a positive surface typically means above or outside. A negative surface means below or inside. If you take a look at cell 3, you have -3 4, meaning below x=4 and at the same time above x=6. The space between x=4 and 6 is "3 -4". Now have a look at cell 4 and see if you can find something similar.
- #5
chengmo
- 9
- 0
Thank you very much Alex A, I got the X-axis wrong. The sign of 1, 2,3, and 4 surfaces in the surface card is wrong
- #6
- #7
Alex A
Gold Member
- 246
- 156
MCNP seems happy. When I try the interactive plotter I see the full D. VisEd does not seem happy from your picture. Maybe VisEd does not like the comment. I do not see an error.
1. What is the geometric coincidence issue in MCNP?
The geometric coincidence issue in MCNP refers to the problem of accurately simulating the interaction of particles with complex geometries, such as a semi-cylinder and cuboid, in a Monte Carlo simulation. This can lead to errors in the calculated results and is a common challenge in many scientific simulations.
2. How does MCNP handle the geometric coincidence issue?
MCNP uses a combination of geometry splitting and ray tracing techniques to handle the geometric coincidence issue. The geometry splitting method divides the complex geometry into smaller, simpler shapes that can be more accurately simulated. The ray tracing method tracks the paths of particles as they interact with the different shapes, allowing for more precise calculations.
3. Can MCNP accurately simulate a semi-cylinder and cuboid in the same simulation?
Yes, MCNP can accurately simulate a semi-cylinder and cuboid in the same simulation. By using the geometry splitting and ray tracing methods, MCNP can effectively handle the geometric coincidence issue and accurately calculate the interactions between particles and these complex shapes.
4. Are there any limitations to MCNP's ability to solve the geometric coincidence issue?
While MCNP is a powerful tool for simulating complex geometries, it does have some limitations. In some cases, the geometry splitting and ray tracing methods may not be able to fully resolve the geometric coincidence issue, leading to some degree of error in the results. Additionally, the accuracy of the simulation may also depend on the specific parameters and settings used in the simulation.
5. Can other simulation software solve the geometric coincidence issue more accurately than MCNP?
There are many different simulation software programs available, each with their own strengths and limitations. While some may have more advanced techniques for handling complex geometries, MCNP is a widely used and well-established program that is continually being improved upon. Ultimately, the accuracy of any simulation will depend on the specific problem being studied and the methods used to solve it.
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