# Topology optimisation of fluids in Stokes flow

**URL:** <https://fenicsproject.discourse.group/t/topology-optimisation-of-fluids-in-stokes-flow/6124>\
**Category:** installation\
**Created:** [June 30, 2021, 11:14pm UTC](https://fenicsproject.discourse.group/t/topology-optimisation-of-fluids-in-stokes-flow/6124 "2021-06-30T23:14:38Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![mihabibi](https://avatars.discourse-cdn.com/v4/letter/m/6f9a4e/32.png) [@mihabibi](https://fenicsproject.discourse.group/u/mihabibi)\
**Post date:** [June 30, 2021, 11:14pm UTC](https://fenicsproject.discourse.group/t/topology-optimisation-of-fluids-in-stokes-flow/6124/1 "2021-06-30T23:14:38Z")

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Dear all,

As a test, I would like to reproduce the result of example ([Topology optimisation of fluids in Stokes flow](http://www.dolfin-adjoint.org/en/latest/documentation/stokes-topology/stokes-topology.html)). I installed everything with Conda as it was recommended but I get the following error:  
File “/home/mihabibi/anaconda3/envs/fenicsproject\_2018/lib/python3.7/site-packages/pyadjoint/optimization/ipopt\_solver.py”, line 44, in \_\_build\_pyipopt\_problem  
nlp = pyipopt.create(len(ub), # length of control vector  
AttributeError: module ‘pyipopt’ has no attribute ‘create’