Hello,
I want to calculate the dissipation energy of particle collision in ball mill over time. I am not able find any command.
"The damping energy is the dissipated energy due to in-elastic contacts between particles and particle/balls/walls and is physically more related to particle breakage"
The specific damping energy at contact i is given by
Wm=
t
∫ F_dn * dε_n/m_i
0
, where F_dn is the normal damping force, dε_n the normal displacement over a whole contact period t and m_i is the mass of the particles.
Thank you.
deepakpawar.2310 | Sat, 08/05/2023 - 10:17
Hi
Hi
I guess you have to dump the particle contact data using the pair/gran/local command. (https://www.cfdem.com/media/DEM/docu/compute_pair_gran_local.html)
And need to extract normal force and normal overlap for each time step and need to estimate the dissipation energy from above expression
Need to sump it up for whole simulation time.
Thank you
rpareshr | Mon, 08/07/2023 - 12:33
Hello
Hello Sir,
Thank you for reply.
With mentioned command as by you, we can extract the whole normal force but in my case i only want to extract normal damping force without spring force. Please guide me if have any idea.
Thanks
jobinraju | Fri, 01/26/2024 - 16:14
Possible
With a little bit of coding, it's possible. Look at this answer: https://www.cfdem.com/forums/accessing-particleswereincontact-var-outsid...
Basically, you add another 'pair history property' (pair_gran.h), update its value in a contact model (normal_model_hertz.h). Now write a new fix, where you can access the new collision property via pair_gran->get_history_value_offset and pair_gran->listgranhistory->firstdouble. Now you have your required value dug up to the "surface". From here the array of the new fix can access the value and can be output to a file/console.
I know the above is an abstract solution. But you can refer to fix_break_particle.cpp, where something very similar is implemented.