LIGGGHTS® - User Forum

Hi all,

Form LIGGGHTS, I can output the contact forces acting on a selected particle in the soil assembly directly. Does anyone know whether LIGGGHTS can output the mean normal stress acting on a single particle and how to output this data? Some description of such mean normal stress (p'=sigma_ii'/3) can be seen in the attached picture.

Best,
Rachel

Hello,

I am having an issue with setting up one of my meshes as a heat source.

In my simulation I have two different meshes however I only want one mesh to be a heat source.
I assigned a constant temperature of 400 to cad2 as shown below but I get a nasty looking error message with this (copied to bottom of post)

Dear all,

Are there any easy ways to do following things for post results of pure particle flow, such as in paraview:

1) How to do temporal and spatial averaging for particle velocity? I mainly want to get the vector field like fluid flow.

2) How to track the particles in a region specified at time=0 s?

Looking forward to any suggestions. Many thanks.

Best wishes
Solient

Hi guys,

I use the move/mesh command to move mesh linearly along the z-direction.
I'm using the SI unit system. I set the velocity as 0.05 mm/s for the mesh.
fix meshmove all move/mesh mesh Cad1 linear 0 0 -0.00005
And my timestep is 0.00001

But after I check the result it moves way much faster.

I don't know how it happened.

Help me please.

Hey community,

i need to calculate the temperature of particles grouped in a defined region. Unfortunately I only get zero on the calculated compute command.

Could someone check it and tell what I am doing wrong. What do I have to setup to get it to a file or get the result ?

Thank you very much in advance.

David

I could send you script file on request

1. I try to set the region:
#set region temperature

region regionTemp1 block 0.6 1.5 -0.6 0.6 0 1.4 units box
group sectionTemp1 region regionTemp1

Hi,

I want to increase my wall velocity after a certain timestep. It should be increased at my define formula until run ends. How could I do this please help. Thanks

Hello together,

I have a question about implementing STL files via the fix mesh/surface command.
I know that it is possible to move and rotate the Mesh directly in this command. But as definition, the rotation is only possible around an axis which origin ist the 0,0,0.
Is there a posibillity to change this origin in this command?

The move/mesh command allows to define the rotational axis completely free.
Thanks for your answers,

Best regards,
Nils

Hello,

I am analyzing particles trajectory off conveyor belt. I have these two fixes in the script;

fix conv all mesh/surface file meshes/conv_200.stl type 4 move 0.0 0.0 0.0 rotate axis 0 1 0 angle 13.5 surface_vel 0.5 0.0 0.0 #Thats the conveyor belt
fix h_pulley all mesh/surface file meshes/head_pulley.stl type 4 move 0.0 0.0 0.0 rotate axis 0 1 0 angle 13.5 curvature 1e-6 #Thats the head-pulley

Hi Everyone,

I am a beginner in Liggghts and want to use Paraview for which I need to generate .pwd type of files from the superquadric (3.8.0) release 7. Any guidance will be very helpful. My system is CENTOS 7.

Thanks,
Sounik

Hi all,

I am using the fix ave/euler command to calculate the stress tensor. Can I specify a region to calculate the stress tensor instead of the whole domain? I do not understand the function of basevolume_region but guess it is not used to define the region for the calculation.

Thanks
Linhan