Help solving Simulink numerical oscillation

In summary, Tusike posted a thread on Physics Forums a week ago seeking help with a problem involving two chambers connected by a valve. They have found a solution for the oscillation that occurs and are now looking for assistance with expanding their calculations to higher dimensional cases. They have also presented some ideas for this expansion in their 1D case.
  • #1
Tusike
139
0
Hi!

I posted a new thread about a week ago, but so far no one was able to help me:

https://www.physicsforums.com/showthread.php?t=761892

I wasn't sure if I posted in the right forum, so I'm posting it here hoping to reach a wider audience :)

Any help is greatly appreciated!

-Tusike
 
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  • #2
Hi!

I think I found a solution to my problem in the case of two chambers connected by a valve.

I can calculate the amplitude of the oscillation that occurres, and have given a condition that leads to the oscillation damping, and my results agree with what I see in Simulink.
If anyone would go over my mathematical formulation given in the attachments, I would greatly appreciate that.

However, I'm having trouble expanding my math to more chambers = higher dimensional cases.
So far, I have been able to calculate the amplitude of oscillation for 3 chambers, but couldn't give a precise formulation of a solution such as in the 1D case. I will upload a document of my calculations for this as soon as I type it in.

I presented some ideas in the 1D case which could be used to expand to higher dimensions. If anyone could give me ideas on how to do that, and if the way I'm trying seems to be correct or not, I would also be very thankful.

Thanks!

-Tusike
 

Attachments

  • numerical_analysis.pdf
    51.4 KB · Views: 273
  • numerical_analysis.docx
    22.5 KB · Views: 259

1. How can I prevent numerical oscillations in my Simulink model?

One way to prevent numerical oscillations is to use smaller time steps in your simulation. You can also try using a different solver, such as a variable-step solver, to improve the accuracy of your results.

2. What causes numerical oscillations in Simulink?

Numerical oscillations occur when there is a mismatch between the step size used in the simulation and the time scales of the system being modeled. This can lead to errors in the numerical integration and result in oscillations in the solution.

3. How do I know if my Simulink model is experiencing numerical oscillations?

If your model is exhibiting unexpected or unrealistic behavior, such as rapidly changing values or large oscillations, it may be a sign of numerical oscillations. You can also check the solver settings and simulation results for any warnings or errors related to numerical stability.

4. Can I use a fixed-step solver to avoid numerical oscillations?

While a fixed-step solver can help in some cases, it may not be the most effective solution for preventing numerical oscillations. It is recommended to use a variable-step solver that can dynamically adjust the time step to match the time scales of your system.

5. Are there any other techniques for avoiding numerical oscillations in Simulink?

In addition to using smaller time steps and a variable-step solver, you can also try using numerical damping techniques, such as the implicit Euler method or the trapezoidal rule. These methods can help stabilize the solution and reduce the occurrence of numerical oscillations.

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