Timestep Error

[reisi...@gmail.com]

Dear Glenn,

I’m running a 1D PFLOTRAN reactive transport simulation of using small timesteps (INITIAL_TIMESTEP_SIZE = 1e-7 y, MAXIMUM_TIMESTEP_SIZE = 1e-6 y), but the simulation stops with the error “Maximum timestep exceeded. Exiting!” . Could you please advise how I can address this issue so the simulation can complete successfully?

Maximum timestep exceeded.  Exiting!

PMCSubsurfaceFlow

 Total Time: 2.5148E+03 seconds

 FLOW TS SNES steps = 999918  newton = 1000084  linear = 1000084  cuts = 0

 FLOW TS SNES Wasted Linear Iterations = 0

 FLOW TS SNES Wasted Newton Iterations = 0

 FLOW TS SNES time = 2046.3 seconds

PMCSubsurfaceTransport

 Total Time: 6.1792E+03 seconds

 TRAN TS SNES steps = 999999  newton = 1000220  linear = 1000220  cuts = 35

 TRAN TS SNES Wasted Linear Iterations = 67

 TRAN TS SNES Wasted Newton Iterations = 67

 TRAN TS SNES time = 5593.5 seconds

 Wall Clock Time:  9.3913E+03 [sec]   1.5652E+02 [min]   2.6087E+00 [hr]


Regards,

Fatemeh

[Hammond, Glenn E]

Fatemeh,

Try increasing the maximum number of time steps using the MAXIMUM_NUMBER_OF_TIMESTEPS card.

https://documentation.pflotran.org/user_guide/cards/subsurface/timestepper_card.html

Glenn

From: pflotra...@googlegroups.com <pflotra...@googlegroups.com> on behalf of reisi...@gmail.com <reisi...@gmail.com>
Date: Saturday, October 18, 2025 at 3:49 PM
To: pflotran-users <pflotra...@googlegroups.com>
Subject: [pflotran-users: 8596] Timestep Error

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