# I need help solving this problem using FEniCS

**URL:** <https://fenicsproject.discourse.group/t/i-need-help-solving-this-problem-using-fenics/12947>\
**Category:** variational formulation\
**Created:** [December 5, 2023, 5:25pm UTC](https://fenicsproject.discourse.group/t/i-need-help-solving-this-problem-using-fenics/12947 "2023-12-05T17:25:03Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![italo8223](https://avatars.discourse-cdn.com/v4/letter/i/c57346/32.png) [@italo8223](https://fenicsproject.discourse.group/u/italo8223)\
**Post date:** [December 5, 2023, 5:25pm UTC](https://fenicsproject.discourse.group/t/i-need-help-solving-this-problem-using-fenics/12947/1 "2023-12-05T17:25:03Z")

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Whenever I try to solve this problem I get an error that I don’t know what it means. The problem is

\begin{equation}  
\begin{cases}  
\frac{\partial u}{\partial t} = \nabla \cdot (D \nabla u) + \nabla \cdot (\xi u \nabla p)+ (\alpha\_A - \beta\_{AB})u - \alpha\_Au^{2} \ \  
u = 0 \ [0, l] \times {h} \ \  
u = 1 \ [0, l] \times {0} \ \  
\frac{\partial u}{\partial x} = 0 \ \ para \ \ x =0 \ \ e \ \ x = l \ \  
u(x,y,0) = 1 - \frac{y}{h} \ \  
\end{cases}  
\end{equation}

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<div class="post-metadata">

**Author:** ![spcvanschie](https://avatars.discourse-cdn.com/v4/letter/s/76d3ee/32.png) [@spcvanschie](https://fenicsproject.discourse.group/u/spcvanschie)\
**Post date:** [December 5, 2023, 8:09pm UTC](https://fenicsproject.discourse.group/t/i-need-help-solving-this-problem-using-fenics/12947/2 "2023-12-05T20:09:33Z")

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It is quite impossible to help you without knowing what error message you’re getting, without seeing any of your code and without knowing what version of FEniCS(x) you’re using. I strongly urge you to have a look at [this topic](https://fenicsproject.discourse.group/t/read-before-posting-how-do-i-get-my-question-answered/21/1) and to add the relevant information to your post, because at the moment we cannot help you in any way.