# Changing computational domain

**URL:** <https://community.freefem.org/t/changing-computational-domain/784>\
**Category:** General Discussion\
**Created:** [February 5, 2021, 1:42pm UTC](https://community.freefem.org/t/changing-computational-domain/784 "2021-02-05T13:42:21Z")\
**Posts on this page:** 2\
**Page:** 1

<div class="post-metadata">

**Author:** ![zese](https://yyz2.discourse-cdn.com/flex030/user_avatar/community.freefem.org/zese/32/917_2.png) [@zese](https://community.freefem.org/u/zese)\
**Post date:** [February 5, 2021, 1:42pm UTC](https://community.freefem.org/t/changing-computational-domain/784/1 "2021-02-05T13:42:21Z")

</div>

Dear all

I want to start my calculation with a larger domain (TH) and then decrease it based on the for example the magnitude of velocity and continue the simulation just for the domain that velocity is great (Th2) and repeat it every time step.

In fact, I am going to control a flow by some volume force to decrease radial velocity. However, my domain at first is too big (TH) and I want to decrease it in every time step based on the some gradients. is it possible to change the computational domain automatically in freefem?

Best regards,

---

<div class="post-metadata">

**Author:** ![denis.crete](https://avatars.discourse-cdn.com/v4/letter/d/9d8465/32.png) [@denis.crete](https://community.freefem.org/u/denis.crete)\
**Post date:** [February 6, 2021, 4:36pm UTC](https://community.freefem.org/t/changing-computational-domain/784/2 "2021-02-06T16:36:45Z")

</div>

Hello,  
I would suggest looking in the documentation at examples “Laplace-Adapt-3d.edp” in chapter 5.17 and the scripts examples+±mpi/MPIGMRES[2]D.edp, discussed at the end of 10.6.1: they illustrate possible uses of function “trunc”.  
HTH  
Denis