# Unsteady three dimensional PETSc

**URL:** https://community.freefem.org/t/unsteady-three-dimensional-petsc/992
**Category:** General Discussion
**Created:** [May 25, 2021, 3:22pm UTC](https://community.freefem.org/t/unsteady-three-dimensional-petsc/992 "2021-05-25T15:22:32Z")
**Posts on this page:** 1
**Showing post:** 4

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### Author: ![prj](https://avatars.discourse-cdn.com/v4/letter/p/ecae2f/32.png) [@prj](https://community.freefem.org/u/prj)
#### Post date: [May 27, 2021, 4:33pm UTC](https://community.freefem.org/t/unsteady-three-dimensional-petsc/992/4 "2021-05-27T16:33:25Z")

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1. Writting the solution in a single file means centralizing said solution on a single process. It’s a serious bottleneck once you start looking at decomposition with thousands of processes. It’s doable nonetheless, you can for example [search the forum to find a solution](https://community.freefem.org/t/global-solution-with-petsc/239).
2. It will all depend on your discretization scheme and time-stepping.

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