Model error regarding maximum time step exceeded

[Bisesh Joshi]

Hello everyone,

I'm encountering this error of maximum time step exceeded at 2.73965E+03 year every time I run the model. The interesting thing is that it again runs when I restart from this checkpoint until again it reaches to year 2.73965E+03 year and again fails for the same reason. I want to run the model for 5000, 10000 year to see when it stabilizes.

I'm suspecting it to be due to large timestep at that timepoint; however, using timestepper with a timestep reduction factor of 0.90 has not fixed the issue.

Please let me know if anybody has any suggestions?

Thank you!

Best regards,

Bisesh

--

Bisesh Joshi

PhD student

Water Science and Policy

Graduate College

University of Delaware

901-297-6761

[Won Woo Yoon]

Dear Bisesh,

You might set the MAXIMUM_NUMBER_OF_TIMESTEPS in TIMESTEPPER larger than 999,999 which is a default value.

Since your model reached 999,999 at about 2,740 years, I would recommend a value larger than 5,000,000.

Sincerely

Won Woo Yoon 

2025년 12월 7일 (일) PM 1:40, Bisesh Joshi <bjo...@udel.edu>님이 작성:

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[Bisesh Joshi]

Thanks for the suggestion, Won!

To view this discussion visit https://groups.google.com/d/msgid/pflotran-users/CAKarx-yH8eY%2Bhk9tTcj_xaPLKcvfHQ0JMrHO2JUAi9AX0pqEWw%40mail.gmail.com.

[Bisesh Joshi]

Hi Won,

This approach is not working. 

Still fails at the same time.

Any other suggestions?

Thank you.

Best regards,

Bisesh

[Hammond, Glenn E]

Please send the block that you added in your input file. I created a very small problem and set the number of steps to 999999 + 1 = 1000000 steps.

NUMERICAL_METHODS FLOW

  TIMESTEPPER

     MAXIMUM_NUMBER_OF_TIMESTEPS 1000000

  /

END

The simulation ran for 1,000,000 steps before stopping due to reaching the maximum number of time steps (actually ​****** steps as line can only handle 6 digits).

Glenn

From: pflotra...@googlegroups.com <pflotra...@googlegroups.com> on behalf of Bisesh Joshi <bjo...@udel.edu>
Date: Monday, December 8, 2025 at 6:49 AM
To: pflotra...@googlegroups.com <pflotra...@googlegroups.com>
Subject: Re: [pflotran-users: 8626] Model error regarding maximum time step exceeded

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[Bisesh Joshi]

Hi Glen,

Thanks for the response.

Here I have attached the snippet.

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[Hammond, Glenn E]

Does setting the maximum number of time steps to 5 work?

Glenn

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[Bisesh Joshi]

Yes,

It did terminate the simulation at time step 5.

In my previous snippet, I think, simulation terminated at sns time step 999999, even when I increased time step to 50000000.

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[Hammond, Glenn E]

Please run the attached input deck to 1.1M time steps. I was able to do this myself. You will need to increase the number of digits in the output. To do so, change the “i6” at the following line of code to i7 or i8:

https://bitbucket.org/pflotran/pflotran/src/3f719acd3436dbf159006967c6f9fd674d4a401f/src/pflotran/timestepper_base.F90#lines-1167

Glenn

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[Bisesh Joshi]

Hi Glenn,

Your input file runs fine on my machine. Also, even with changing i6 to i8, I still get ****** in time step. Should I do ' Make pflotran'? 

However, I'm still unable to figure out the issue, I tried changing sns type to NTRDC as well.

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[Hammond, Glenn E]

Anytime a compiled code (e.g., C, C++, Fortran, Java, Rust, etc.) is modified, one must recompile it (i.e., in this case ‘make pflotran’ and add ‘-j4’ to compile faster in parallel).

I am unsure what to suggest since my input deck works, changing to a max of 5 in your input deck works, but changing to > 999999 in your input deck doesn’t work….

Glenn

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[Bisesh Joshi]

Hi Glenn,

It worked now. I have restarted computer and have increased the maximum timestep to 10 day.

Thank you so much.

Best regards,

Bisesh Joshi

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Sent: Monday, December 8, 2025 5:11:56 PM
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Subject: Re: [pflotran-users: 8633] Model error regarding maximum time step exceeded

 

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