# Viscous term in NS

**URL:** <https://community.freefem.org/t/viscous-term-in-ns/4058>\
**Category:** General Discussion\
**Created:** [September 7, 2025, 2:48pm UTC](https://community.freefem.org/t/viscous-term-in-ns/4058 "2025-09-07T14:48:59Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![goetze](https://avatars.discourse-cdn.com/v4/letter/g/7bcc69/32.png) [@goetze](https://community.freefem.org/u/goetze)\
**Post date:** [September 7, 2025, 2:48pm UTC](https://community.freefem.org/t/viscous-term-in-ns/4058/1 "2025-09-07T14:48:59Z")

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Hi everyone,

I’m trying to solve the term

\nabla\cdot(\nu\_t(\nabla\mathbf{u}+\nabla\mathbf{u}^T))

and extract the x and y component but I’m struggling with implementation. I guess it’s best to use varf but I’m pretty new to FreeFem and have no idea how to do this.  
Thank you

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<div class="post-metadata">

**Author:** ![fb77](https://yyz2.discourse-cdn.com/flex030/user_avatar/community.freefem.org/fb77/32/3796_2.png) [@fb77](https://community.freefem.org/u/fb77)\
**Post date:** [September 15, 2025, 9:43am UTC](https://community.freefem.org/t/viscous-term-in-ns/4058/2 "2025-09-15T09:43:08Z")

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In the FreeFem documentation you can look at the section “The system of elasticity” to see how such term is handled.