# Streamlines using the Elmer method **URL:** https://community.freefem.org/t/streamlines-using-the-elmer-method/3407 **Category:** General Discussion **Created:** [July 20, 2024, 3:56pm UTC](https://community.freefem.org/t/streamlines-using-the-elmer-method/3407 "2024-07-20T15:56:32Z") **Posts on this page:** 1 **Showing post:** 2
### 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: [July 20, 2024, 4:52pm UTC](https://community.freefem.org/t/streamlines-using-the-elmer-method/3407/2 "2024-07-20T16:52:51Z")
A method is proposed in > [@Uzawa scheme for stokes bingham flow](https://community.freefem.org/t/uzawa-scheme-for-stokes-bingham-flow/3233/16): > > In that paper the flow is taken incompressible, whereas in your code you use compressible. This is why the solution is different (but looks correct). You can modify easily your code to do the incompressible case, by using the extra variables p,q as solve bing([ux,uy,p],[vx,vy,q]) and adding -int2d(Th)(p\*Divergence(vx, vy)+q\*Divergence(ux, uy)) But then it happens that the scheme converges extremely slowly (you need thousands of iterations). In order to improve it you should use the Augmente… from “Another point is that your computation of the stream function…” The important thing is the \varepsilon. If your u is P1, you should take the stream function in P2. If your u is P2, you should take the stream function in P3. --- _[View the full topic](https://community.freefem.org/t/streamlines-using-the-elmer-method/3407)._