# [Getdp] Laplace problem, Dirichlet and Neumann condition.

Isabel Martínez isabelXXI21 at hotmail.com
Thu Oct 10 13:59:17 CEST 2019

```Dear all:

This is the first time I am using getdp. I am trying to solve a Laplace problem with mixed boundary conditions in a cylinder. The equations are:

- Laplacian N = 0 inside the cylinder.

N = 0 on the side of the cylinder.
grad N * normal[] = - CompX[Normal[]] on the bases of the cylinder.

I have my .geo and .pro files, but when getdp computes the solution the Neumann condition is not fulfilled. I checked the normal vectors with the gui of gmsh and the postprocesing of getdp and they looked good. I tried with different ways of define my geometry but it gives me the same results.

I put the Dirichlet condition as a constraint and the weak formulation is:
[Dof{d N} ,{d N} ]_inside the cylinder
+ [CompX[Normal[]] ,{N} ]_on the bases of the cylinder.

I am using getdp-3.2.0 and gmsh-4.4.1 for Windows64. I also tried with the version from the 1st of October of 2019 of ONELAB.

I can't find what is wrong, I would be thankful if someone can help me. I attached the .geo and .pro files.

Thank you in advance.
Isabel.

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://onelab.info/pipermail/getdp/attachments/20191010/ef6c4ccf/attachment.html>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: Geo.geo
Type: application/octet-stream
Size: 1821 bytes
Desc: Geo.geo
URL: <http://onelab.info/pipermail/getdp/attachments/20191010/ef6c4ccf/attachment.geo>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: Pro.pro
Type: application/octet-stream
Size: 2938 bytes
Desc: Pro.pro
URL: <http://onelab.info/pipermail/getdp/attachments/20191010/ef6c4ccf/attachment.pro>
```