model non-convergence

[Mamatha Prabhakar]

"Warning: FAILED TO MEET SOLVER CONVERGENCE CRITERIA IN TIME STEP    1 OF STRESS PERIOD    1" . Please help me to solve this error encountered while running visual Modflow Flex7. 

[Biswajit Das]

Time step mismatch.. correct the time step

On Thu 29 Apr, 2021, 7:18 PM Mamatha Prabhakar, <mamathapr...@gmail.com> wrote:

"Warning: FAILED TO MEET SOLVER CONVERGENCE CRITERIA IN TIME STEP    1 OF STRESS PERIOD    1" . Please help me to solve this error encountered while running visual Modflow Flex7. 

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[Garth Cooper]

Hi Maratha,

Please look at the .lst (results) file for more hints. Also if you can share your .lst file and I can give you more advice.

Here is some general advice when your model doesn’t converge:

-Check that you have adequate inner and outer iterations in your solver setttings

-increase your head close criterion to 0.1 to get your model to work - look at the model results (water levels and water balance) and see if the results make sense then slowly decrease the head criterion by 0.1, 0.01, 0.001.

-check that you have enough time steps for each stress period. Increase the time steps until you get an answer that converges.

-check that you have setup your model properly and that you have not put any incorrect boundary conditions. To fix this up go to the Nam file and delete each boundary and run the model.

To really help you could you please send the lst file or at least a screen shot of the last stress period?

On 29 Apr 2021, at 9:48 pm, Mamatha Prabhakar <mamathapr...@gmail.com> wrote:

"Warning: FAILED TO MEET SOLVER CONVERGENCE CRITERIA IN TIME STEP    1 OF STRESS PERIOD    1" . Please help me to solve this error encountered while running visual Modflow Flex7. 

[Richard B. Winston]

See question K in  https://water.usgs.gov/ogw/modflow/MODFLOW-2005-Guide/index.html?frequently_asked_questions.htm

[Mamatha Prabhakar]

Please find attached screenshot of LST file. Also, I am getting mass balance only for a single stress period (screenshot attached). Please help me. Thank you. 

[Ashutosh]

Hej,

I see a lot of stress periods. Did you achieve non convergence in one of them or all of them. Since the error discrepancy is less than 1% i will say that your convergence criteria might be too strict. If you had a high convergence criteria and still you get this non convergence, try increasing the number of iterations.

Regards

Ashutosh 

On 13 May 2021, at 09:37, Mamatha Prabhakar <mamathapr...@gmail.com> wrote:

Please find attached screenshot of LST file. Also, I am getting mass balance only for a single stress period (screenshot attached). Please help me. Thank you. 

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<stress period.png>

<LST.png>

<Percent discrepancy.png>