[magicbretzel]

Hi,

I am running RANS of an IC engine for many cycles using a coarse mesh (about 250,000 cells max). I am getting cycle-to-cycle oscillations in the mean quantities, shown here for temperature. I was slightly surprised by this result as after a 2/3 cycles I was naively expecting the RANS framework to "converge" to a periodic solution with a period of one cycle. Is it common to observe such non-periodic behavior?

Thanks!
Guillaume

[nitesh.attal]

Originally Posted by magicbretzel

Hi,

I am running RANS of an IC engine for many cycles using a coarse mesh (about 250,000 cells max). I am getting cycle-to-cycle oscillations in the mean quantities, shown here for temperature. I was slightly surprised by this result as after a 2/3 cycles I was naively expecting the RANS framework to "converge" to a periodic solution with a period of one cycle. Is it common to observe such non-periodic behavior?

Thanks!
Guillaume

Hello Guillaume,



This is an expected behavior for certain types of engines and operating conditions.



We have demonstrated that CONVERGE is capable to predict cycle-cycle-variation (CCV) and recommend you to read the following and similar papers. Please let me know if you have any followup questions.

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Probst, Daniel M., et al. "Predicting Cycle-to-Cycle Variation With Concurrent Cycles in a Gasoline Direct Injected Engine With Large Eddy Simulations." Journal of Energy Resources Technology 142.4 (2020).



Accelerating URANS Cycle-to-Cycle Variation Studies via Parallel Perturbation Method, https://api.convergecfd.com/wp-conte...oads/Attal.pdf

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