How the force is accumulated on each atom

Submitted by Jeff_DONG on Mon, 04/08/2019 - 02:29

Hi guys,

I am trying to extract the total cohesion force(easo capillary) for each atom, but I currently do not know how the force is accumulated for each atom.

Now, what I have done is:
1, I can use "compute_pair_gran_local" to extract the easo capillary force, but it is only for each pair. So I think I need to accumulate them to obtain the total force.
2, To look at the similar coding, I have found the f[i][0], f[i][1], f[i][2] in "compute_property_atom" and "dump_custom", both extract f[][] variables to 'fx'. However, I still do not understand how the f[][] variables are calculated(accumulated) based on each contact pair, or where I can find the coding.

I am also a new user to C plus, so could anyone give me some suggestions?

Very appreciate!

Regard,
Jeffrey

syedUConn | Fri, 06/21/2019 - 23:07

For my project, I need to make a model of fluid bed drying. I have hot air coming in from the bottom and heating wet particles and eventually drying the particles. For this, I could run the simulation up to the heat transfer from the fluid to the particle, which is pretty straightforward and a lot of tutorials helped me. But, now I am really stuck as I need to incorporate moisture in particles and simulate drying. My first idea was to use cfdemSolverPisoSTM and consider the moisture as species but I do not know what is speciesCCapacity and how can I relate this parameter to the drying rate. So I could not go anywhere.
Then I thought of using the easo capillary model. I incorporated the model as specified by the documentation. But I receive the following error (as I need to know the liquid content and how it varies with time),

dump dmp all custom 20000 ../DEM/post/dump*.liggghts_run id type x y z ix iy iz vx vy vz fx fy fz omegax omegay omegaz radius f_Temp[0] f_heatFlux[0] f_surfaceLiquidContent[0]
ERROR: Could not find dump custom fix ID (../dump_custom.cpp:1384)
(../dump_custom.cpp:1384)

Also before the error, I receive the following warning,

WARNING:
The contact model you specified is not located in any whitelist.
Because of this the model will be run in an unoptimized version (increasing runtime by up to 20%).
In order to optimize this model you have the following options:
(i) Run the genAutoExamplesWhitelist.sh script in your LIGGGHTS(R) source folder to automatically parse the input script
(ii) Add the model combination by hand to your style_contact_model_user.whitelist that can be found in your LIGGGHTS(R) source folder
If you perform one of the steps above LIGGGHTS(R) needs to be recompiled to generate the optimized code.

(../contact_models.h:364)

I will really appreciate if someone can give some input for this.

Thanks in advance