Direct Simulation Monte Carlo(DSMC) corner boundary problem

In summary, the individual is seeking advice on how to fix incorrect results caused by the diffuse boundary condition in their DSMC code. Suggestions include implementing a more accurate boundary condition or using a hybrid method. They also mention the known issue of corner boundary problems in particle methods and suggest looking into literature or consulting with other researchers for potential solutions.
  • #1
Noh-hoon Lee
8
0
Hello, I'm developing the DSMC code of 3d box(for test, no velocity, just applying the thermal boundary condition of 273 K).

If there are diffuse boundary only up and down and others are periodic, simulation result is good.

But if diffuse boundary is at all plane, wrong result has come.

So how it can be fixed? If there anyone know about corner boundary problem of Particle method, I need advice or information where I can get the algorithm or concept of corner boundary condition. Please help
 
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  • #2
!

Hello, thank you for reaching out about your DSMC code development. It seems like you are experiencing some difficulties with the diffuse boundary condition in your simulation. One possible solution could be to implement a more accurate boundary condition, such as the Maxwell boundary condition, which takes into account the velocity distribution of the particles at the boundary.

Another approach could be to use a hybrid method, where you combine the DSMC method with a continuum method near the boundary. This can help improve the accuracy of the results near the boundaries.

As for the corner boundary problem, it is a known issue in particle methods and there are various approaches to address it. One possible solution is to use a reflection boundary condition at the corners, where particles are reflected back into the domain instead of being absorbed at the boundary. Another approach is to use a smoothing function near the corners to account for the discontinuity in the particle distribution.

I recommend looking into literature on particle methods and their boundary conditions for more information and specific algorithms. You can also consult with other researchers in the field or attend conferences to learn about the latest developments in this area. I hope this helps and good luck with your code development!
 

1. What is the DSMC corner boundary problem?

The DSMC corner boundary problem is a common issue encountered in Direct Simulation Monte Carlo (DSMC) simulations, which are used to model gas flows at low densities. It occurs when the simulation domain contains sharp corners or edges, causing the molecules in the simulation to behave differently than they would in a smooth, continuous flow. This can lead to inaccurate results and must be addressed in order to obtain accurate simulations.

2. How does the DSMC method handle the corner boundary problem?

The DSMC method uses a particle-based approach to simulate gas flows, where the molecules are represented as individual particles that interact with each other and the boundaries of the simulation domain. In order to address the corner boundary problem, the DSMC method uses a technique called domain decomposition, where the simulation domain is divided into smaller subdomains that are treated separately. This allows for a more accurate representation of the flow near corners and edges.

3. What are some challenges in addressing the corner boundary problem in DSMC simulations?

One challenge in addressing the corner boundary problem is determining the appropriate size and number of subdomains to use in the domain decomposition technique. Too few subdomains may not adequately capture the flow near corners, while too many subdomains can significantly increase the computational cost of the simulation. Another challenge is accurately modeling the interactions between molecules and boundaries, as well as between molecules themselves, in the corner regions.

4. Are there any alternative methods for handling the corner boundary problem in DSMC simulations?

Yes, there are alternative methods for addressing the corner boundary problem in DSMC simulations. One approach is to use a boundary treatment based on the diffuse reflection model, which assumes that molecules near boundaries will be reflected diffusely rather than specularly. Another approach is to use a hybrid method, where the DSMC simulation is coupled with a Navier-Stokes solver to model the flow near boundaries.

5. How can the accuracy of DSMC simulations be assessed in the presence of the corner boundary problem?

The accuracy of DSMC simulations in the presence of the corner boundary problem can be assessed by comparing the results to experimental data or to analytical solutions for simpler flow geometries. Additionally, sensitivity analyses can be performed by varying the number and size of subdomains and examining the impact on the overall results. It is also important to compare the results from different boundary treatment models and to assess the convergence of the simulation results with respect to grid resolution.

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