# The k equation source term from the examples" a large fluid problem" is wrong

**URL:** <https://community.freefem.org/t/the-k-equation-source-term-from-the-examples-a-large-fluid-problem-is-wrong/3104>\
**Category:** General Discussion\
**Created:** [April 17, 2024, 2:44pm UTC](https://community.freefem.org/t/the-k-equation-source-term-from-the-examples-a-large-fluid-problem-is-wrong/3104 "2024-04-17T14:44:47Z")\
**Posts on this page:** 1\
**Page:** 1

<div class="post-metadata">

**Author:** ![localhost](https://avatars.discourse-cdn.com/v4/letter/l/53a042/32.png) [@localhost](https://community.freefem.org/u/localhost)\
**Post date:** [April 17, 2024, 2:44pm UTC](https://community.freefem.org/t/the-k-equation-source-term-from-the-examples-a-large-fluid-problem-is-wrong/3104/1 "2024-04-17T14:44:47Z")

</div>

in the example code, the source term is

prode = -0.126_kp_(pow(2_dx(Ux),2)+pow(2_dy(Uy),2)+2_pow(dx(Uy)+dy(Ux),2))/2;  
prodk = -prode_kp/epp\*0.09/0.126;

but both of them should be negative, so prodk should be

prodk = prode_kp/epp_0.09/0.126;