hello,
I am a new user of LIGGGHTS having some doubts regarding the coarse graining method.
almost all the papers I read dealing with CG state that there are some parameters that are ought to be adjusted in order to obtain physically accepted representation of the unscaled system behaviour by following some rules depending on the scaling factor s.
The thing is that I did not find a command where I can explicitly modify some of these parameters such as contact stiffness K and moment of inertia I.
So am I supposed to change something in the source code in this regards or what?
best wishes,
Nizar
paul | Tue, 10/09/2018 - 09:37
Look around the forum for my
Look around the forum for my patch that enables input of the scaling parameter to use the Bierwisch method of scaling in LIGGGHTS.
For other ways of scaling you may succeed either by inputting a scaled stiffness for the Hertz contact law or implementing it yourself.
NSalloum | Thu, 10/18/2018 - 12:22
hello Paul,
hello Paul,
It seems that this Patch is extremely helpful for my case, but I have an inquiry.
can I simply modify the input.cpp and input.h scripts manually by adding the lines preceded by a (+) in your patch rather than using it as it is? Because actually I am new user of linux.
Moreover, how exactly can I re-compile LIGGGHTS after modifying the src?
best wishes
paul | Fri, 10/19/2018 - 11:36
> can I simply modify the
> can I simply modify the input.cpp and input.h scripts manually by adding the lines preceded by a (+) in your patch rather than using it as it is? Because actually I am new user of linux.
Yes you can also make the changes manually.
> Moreover, how exactly can I re-compile LIGGGHTS after modifying the src?
Just like you did the first time. make auto or using cmake
NSalloum | Fri, 10/19/2018 - 11:40
hey Paul,
hey Paul,
actually I tried applying the modifications mentioned in your patch and recompiled LIGGGHTS by using (make auto) after disabling the VTK option from the Makefiles.user, but I am still getting the following error:
ERROR: Unknown command: coarsegraining 3 (/build/liggghts-LzNUbp/liggghts-3.7.0+repack1/src/input.cpp:259).
So any suggestions that would help me in this regards?
best wishes
Akanksha Rajput | Tue, 12/10/2024 - 07:46
Coarse-graining
Greetings.
I have a couple of doubts regarding the implementation of the coarse-grained method. Please correct me if I am wrong:
1. If I am using Hooke's stiffness model, then I have to scale the stiffness and damping coefficient by the cube of CGR.
2. The inertia is already scaled, and the user doesn't need to change or modify anything while using coarse particles.
3. The derivative of angular velocity (omega) is scaled by 1/CGR (as per literature). For this I have made changes in fix_nve_sphere.cpp and divided the dtfrotate by CGR. Is it the correct way for this parameter scalling?
4. Scaling of drag model: Using, let's say, the Gidaspow drag model, what will the scale and scaleDrag values be?
5. If I have missed out on any other modification, kindly let me know.
Thanking you in advance.