# Pressure projection methods **URL:** https://community.freefem.org/t/pressure-projection-methods/3247 **Category:** General Discussion **Created:** [May 14, 2024, 8:49am UTC](https://community.freefem.org/t/pressure-projection-methods/3247 "2024-05-14T08:49:31Z") **Posts on this page:** 1 **Showing post:** 9
### 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: [May 19, 2024, 3:50pm UTC](https://community.freefem.org/t/pressure-projection-methods/3247/9 "2024-05-19T15:50:02Z")
The equation you have to solve for p^{n+1} is a Laplace equation with non homogeneous Neumann boundary condition. You can look at this post > [@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 “We are thus led to the problem…” --- _[View the full topic](https://community.freefem.org/t/pressure-projection-methods/3247)._