# XDMF: Problems with time-evolution

**URL:** https://discourse.paraview.org/t/xdmf-problems-with-time-evolution/1531
**Category:** ParaView Support
**Created:** [March 26, 2019, 1:05pm UTC](https://discourse.paraview.org/t/xdmf-problems-with-time-evolution/1531 "2019-03-26T13:05:38Z")
**Posts on this page:** 1
**Page:** 1

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### Author: ![Marcin\_Krotkiewski](https://discourse.paraview.org/user_avatar/discourse.paraview.org/marcin_krotkiewski/32/2185_2.png) [@Marcin\_Krotkiewski](https://discourse.paraview.org/u/Marcin_Krotkiewski)
#### Post date: [March 26, 2019, 1:05pm UTC](https://discourse.paraview.org/t/xdmf-problems-with-time-evolution/1531/1 "2019-03-26T13:05:38Z")

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The following problem is observed using Paraview 5.5.1. Because of previously reported bugs this example only works with the version 2 reader.

I am working with time-evolution of models, which share part of the topology, but also modify parts of it. The following file defines each time step from scratch, including the complete Topology and Geometry type XYZ

[ok\_time.xdmf](https://discourse.paraview.org/uploads/default/original/2X/e/eaa20c0c5dc319e83e123b819929f3800b341c63.xdmf) (1.1 KB)

Now, I would like to re-use the parts I can by:

- putting the Topology and X/Y parts of the Geometry into the Domain level
- by using a reference to the global Topology in each time step
- by using GeometryType X\_Y\_Z in individual time steps, where X and Y are references to the Domain level DataItems, and Z is defined per time step

This is done in the following file

[bad\_time.xdmf](https://discourse.paraview.org/uploads/default/original/2X/4/4b3ef99dfa4ae311eb2b3795a7a2d41385ed3d14.xdmf) (1.7 KB)

The model loads, the topology is correct, but the geometry doesn’t change for different time steps. I can tick off the first time step at load time. In that case all time steps look like the second one, and so on. So it seems that the model is created once, for the first loaded time step, and never re-created again. Even though the Z component is different for each time step.