Re: [ESPResSo-devel] lbboundary and slitpore constraint

[Axel Arnold]

Am 12.02.2015 um 13:27 schrieb Harmanjit Singh <address@hidden>:

Please tell me how to implement the distance function in C.  or point me to a source where i can learn that.

If you want the slitpore geometry that is provided with Espresso, then you don’t need to implement it again. Otherwise, just use the current slitpore code as basis, you can easily find that by looking for occurrences of CONSTRAINT_SLITPORE.

In the LB code, you just need to do the same thing as for the other constraints. Again, check e.g. for
LB_BOUNDARY_WAL, which is the plain wall code. You should get the structure behind the code, just do the same for the slit. The files you need to look at are src/core/lb-boundaries.cpp and src/tcl/lb-boundaries_tcl.cpp, plus the respective headers to define a new constant for your constraint.

If you want to contribute your changes, register with github.com, fork our repo espressomd/espresso and commit your changes to your copy. Then you can send us a pull request, which we will review.

Best,
Axel

On Thu, Feb 12, 2015 at 3:40 PM, Georg Rempfer <address@hidden> wrote:

What do you mean by slit pore? If you mean parallel plates, my previous answer still holds:

>> Is there a way to use lb fluid in slitpore? While I tried this the simuation gave error that lbboundary does not accept the slitpore parameter.

>Yes. Read the User's Guide about lbboundary wall

My suggestion to implement your boundary geometry in the C code was meant for more complicated geometries.

>> Is there a way to simulate lb fluid in only specific custom defined boundaries? Like a U-tube.

>Yes. You might be able to construct your channel from several cylinder boundaries. If not you would have to implement a distance function for your boundary shape in the C code.

On Thu, Feb 12, 2015 at 7:33 AM, Harmanjit Singh <address@hidden> wrote:

Dear all,

I have been using Espresso for a month now, I need it to see slitpore as LB BOundary, which is already not accepted as a valid LB boundary. So on suggestion of Georg Rempfer, I tried changing the source codes of the files, i went through the file_1013.pdf by Alex Arnold and then changed the LB boundaries.cpp and Lb boundaries.hpp and there Tcl counterparts. I am not professional coder, but after few tries I got the program to make and make install. It gives no errors now when I passed the slitpore as parameter to the lbboundary command. however I am not really sure it worked because the velocity is always zero when viewed via lbnode.

Is there something that I am missing or something more that needs to be done?

Thank You and Regards

Harmanjit

PS. Please let me know how and where to upload those changed files.

------------------------------------------------
JP Dr. Axel Arnold
ICP, Universität Stuttgart
Allmandring 3
70569 Stuttgart, Germany
Email: address@hidden
Phone: +49 711 685 67609