Starting simulation after changing boundaries-SPH

Submitted by Jotic on Wed, 02/11/2015 - 10:22

Dear users,
I'm using LIGGGHTS to perform SPH simulations, and I would like to start the simulation with:

boundary f f p #periodic boundary in z direction

run it for couple of steps, and after that change the boundaries to:

boundary f f f # all fixed boundaries

and run it.

I tried with:

.
.
.
run 1e5
change_box all boundary f f f remap units box
run 1e5

but it does not work. In the output file I get a message:

.
.
.
Changing box ...
Setting up run ...

and it does not start after that.

Thank for help.

Forums:

JoshuaP | Wed, 02/11/2015 - 11:05

Hi,

what are you trying to simulate? If you wanna simulate a flow in z direction and want to stop that flow after a while, I would insert a primitive wall after certain steps. I'm not sure why you want first periodic boundary and than switch to fix?
Regards

Jotic | Wed, 02/11/2015 - 11:47

I'm simulating a forcibly driven flow in the z direction and want to run the simulation couple of steps without losing particles (it is crucial to use the periodic boundaries) and come to a steady flow, after that switch to fixed boundaries to empty the domain to a certain degree and then again switch to periodic boundaries to become a steady flow. It could be easier to start two simulations with different filling levels, but I need the discharging data too.

JoshuaP | Wed, 02/11/2015 - 11:56

maybe try 'delete_atoms region' or insert an inclined plane during the run, so that the atoms can vanish at the sides. I think there are also more possibilties to discharge the flow without changing boundaries.

I hope I could help