How to output the instant porosity of sphere particles in Liggghts

Submitted by Rachel on Sun, 11/26/2017 - 23:37

Hello everyone,

I am doing a simulation about triaxial compression test using Liggghts, and I am wondering if there is any command for us to obtain the instant porosity or void ratio so that we can output them into a txt file?

Any suggestion or clue is greatly appreciated!

Best regards,
Rachel

Daniel Queteschiner | Thu, 12/07/2017 - 10:33

fix ave/euler + dump euler/vtk introduce a grid and calculate / output the volume fraction per grid cell. Is this what you're looking for?

Rachel | Thu, 12/07/2017 - 23:40

Dear Daniel,

Thanks for this. I didn't find a good command for my use and instead I calculate the total particle volume(neglecting the overlap between particles) and the total region volume, based on which, I calculate the void ratio manually. This seems work well for me. I am not sure whether ave/euler can also give the similar results but I will have a try. Thanks again for your kind help!

Kind regards,
Rachel

qq935074410 | Tue, 09/04/2018 - 00:27

Hi Daniel,

I also need to measure the porosity of packed particles. I tried the command you provide but I can not find any documentation about the dump euler/vtk function. What is the value I got using this function? They are vectors like 0.012500 -0.487952 0.012500. But I don't understand what is this and how can I get the porosity or volume fraction from this value.

Thanks,
Miao