LIGGGHTS® - User Forum

Hi,all
I have a question. I want to simulate particles pouring into a cone. But some problems really confused me!
From the manual on this website :http://nf.nci.org.au/facilities/software/LIGGGHTS/doc/fix_wall_gran.html, I should make the input script like this:
fix conewall all wall/gran/hertz/history 0 0 zcone 0 0.2 0.05 0.1 1
But the LIGGGHTS tells me that "Need to use define style 'mesh' or 'primitive' (fix_wall_gran.cpp:224)"

Another beginner question:

I'd like to output the total number of atoms per timestep. This can already be in the thermo_style output so can be extracted from the log file by editing out all the other compute comments and warnings, but this is a little tedious.

Is there a way to either suppress the comments during the solve or write out the thermo_style output to a separate file? Or perhaps put the atoms # into the dump file?
thanks.

hi
Is it possible to model the interaction of two CAD files? for example in a case: rotating one CAD file may cause rotating another CAD file.

Thanks

My models can't endure with high pressure those particles will penetrate inside the models (particle go through the model when simulate at high pressure i can understand because it makes sense but some times low pressure also). In actually it shouldn't penetrate. I would like to ask you how to make model strong? I think it should has some parameters in LIGGGHTS that can make a wall strong enough for endure with high pressure simulation.

Thank you,
terces907

Another beginner question: I'd like a normal distribution of particle sizes with a mean of 0.000925m and a standard deviation of 0.1.

I've tried this:
fix pts1 all particletemplate/sphere 1 atom_type 1 density constant 2900 radius gaussian number 0.009525 0.1
fix pdd1 all particledistribution/discrete 1. 1 pts1 1.0

but I get this:
ERROR: Probablity distribution: mu-3*sigma < 0, please increase mu or decrease sigma (probability_distribution.h:169)

Do I need to put sigma = (0.009525*0.1)?

Hi, Christoph:

I am doing a simulation involving chemical reaction of particles. In the simulation, I have to update some material properties, such as Young's modulus, Poisson's Ratio, and friction coefficients.... These coefficients must be changed according to their early values (on the last time step), so that I can implement a calculation like:

S_new=S_old+1

When I do it by using the 'variable atom' commands, errors always take place. This algorithm is easy to implement in C++ or other languages. But, it becomes a wrong statement in Liggghts. Do you know why?

This is a beginner question, but I haven't had much luck with it. I have some moving and some static geometry. I would like to only dump the moving geometry to keep the file size down. Ideally I would like to dump all moving geometry parts into a single stl. I'm not sure the syntax to do this. In the meantime I've tried to export each part separately using this:

dump dumpstl body mesh/stl 160 post/body_*.stl
dump dumpstl1 shaftR mesh/stl 160 post/shaftR_*.stl
dump dumpstl2 shaftL mesh/stl 160 post/shaftL_*.stl

I simulated the bubble reactor and I consider the bubbles as dem particles. The bubbles came out from the inlet at a certain velocity, the diameter of bubbles are treated as constant. How can I insert the bubbles to make them fit the certain velocity conditions? Can the insert_stream command works it out?

I simulated bubbles as dem particles, which lifted in the water and came out at the top of the difined box region. How should I set up the boundary conditions of outlet to make the bubbles disappeared when they came out the box? Which command can I use or should I modify the source code to realized it?
thank you for you help!!

thanks,
Zhao

Hi everyone,

I am trying to deposit particles with the ''fix deposit'' command, but I do not know how to define the radius and density of the particle. I tried to use the ''create_atoms'' and ''set'' command, but the dump file shows the radius is not the same as I defined. Is there anyone know how to modify it?

Thanks.