Hi everyone!!
I have a wall rotating and I need to track the position of one of the nodes in the mesh. I have been reading the LIGGGHTS manual and I haven't found anything that could help me. I also was reading topics on the forum but I haven't found anyone who faced this problem before.
I thought the lines below might do the job for me but it didn't work.
variable yPos equal f_wallname[1][2] --> I thought that number "1" would be the node ID and "2" the y coordinate of it.
fix position print 100 "${yPos}" title "y_position" file position.csv screen no
I can overcome the problem generating a csv file using Paraview although it would be tedious. The ideal solution is to have LIGGGHTS printing it out for me.
Thanks !
Regards,
Arnón
richti83 | Wed, 02/27/2019 - 20:10
When you know the initial
When you know the initial position of the node-of-interest and the movement you can compute the time-depending position using an equal style variable.
variable P0x equal 0 #get P0 from Paraview by selecting node in 3D View and have a look in spreadsheet view
variable P0y equal 0
variable P0z equal 1
variable vx equal 0
variable vy equal 0
variable vz equal 1
#
variable t equal step*dt
variable Px equal ${P0x}+${vx}*v_t
variable Py equal ${P0y}+${vy}*v_t
variable Pz equal ${P0z}+${vz}*v_t #note the difference between $-style and v_ style variables
the fix wall does not work as you thought, it does not compute a matrix for every node you can access from scriptlevel.