Hi Marouane, Suppose that you did not disable the output for any family, then yes, the row number (starting from 0) will be the the IDs used in the contact file. Note that "A" and "B" marks owner numbers. If you are using spherical elements, then that's not an issue; if you are using multi-sphere clumps, the it's the IDs of the clumps, not individual spheres.
Suppose you did disable the output for some families, then in that case, a current weakness is that some clumps may not be present in the XYZ output file, thus effectively "skipping" some numbers and making the row numbers and the contact A and B not correspondent. If that is the case, I can implement a utility to include the owner number in the XYZ output file for you to use. Thank you, Ruochun On Thursday, November 28, 2024 at 8:58:02 PM UTC+8 ermaro...@gmail.com wrote: > Hello, > > I have a follow-up question regarding the particle IDs in the output > files. > > In the *position/velocity file*, I don’t see any explicit IDs for the > particles, whereas in the *contact file*, the IDs (A and B) are clearly > specified. Should I assume that the IDs in the contact file correspond > directly to the row numbers in the position/velocity file? Or is there > another mapping logic I should follow? > > Thank you, > > Marouane > > Le mardi 6 août 2024 à 09:35:39 UTC+2, Ruochun Zhang a écrit : > > Hi Marouane, > > So in *Define.h* starting from line 160, I did give some explanations on > what those components are. I know this is not the best way in the world to > make documentations, but before a better one is in place you at least have > some access to the information. > > To answer your questions, the forces are applied by B on A; the force > magnitude and point of action are in the global frame. > > Thank you, > Ruochun > > On Monday, August 5, 2024 at 6:54:39 PM UTC+8 ermaro...@gmail.com wrote: > > Hello, > > Thank you, Ruochun Zhang, for your response; it was very helpful. I have a > follow-up question: In the DEMdemo_ContactChain example, we use the line > DEMSim.SetContactOutputContent(DEME_POINT > | OWNER | FORCE | CNT_WILDCARD); to generate a CSV file similar to the > attached one. My question is, does the force displayed in the file > represent the force applied by B on A or by A on B? Additionally, are the > force coordinates expressed in the reference frame related to the contact > plane or in the absolute reference frame? If they are in the contact > plane's reference frame, is there a way to convert them to the absolute > reference frame? > > Thank you, > Marouane > Le samedi 20 juillet 2024 à 11:15:08 UTC+2, Ruochun Zhang a écrit : > > Hi Marouane, > > Stock output methods *WriteSphereFile *and *WriteClumpFile *cannot add > contact information to the file. You can instead consider using the > dedicated method *WriteContactFile*. It will write the information of all > current contacts (geometries involved, contact point, force > magnitude/direction, etc., and you control what goes to the output by > *SetContactOutputContent*) to a file. Then you post-process the file to > get the "contact map" you want. *DEMdemo_ContactChain *is an example that > uses this method. If you have trouble interpreting the output contact file, > please post on the forum. > > I'd like to add that if you just need the contact pairs (IDs) and the *total > *force each clump experiences as a result of all the contacts surrounding > it, there's another approach. *DEMdemo_Indentation* uses *GetClumpContacts > *to query the IDs of the owners that are in contact with each clump, then > use this information to build a "contact map." Then the *total *force of > each clump experience can be extracted via trackers. The caveat, as I > mentioned, is you cannot easily get *each *force pair concerning a clump > because it's stored in a different way in memory to improve efficiency. > > Thank you, > Ruochun > > On Saturday, July 20, 2024 at 12:51:03 AM UTC+8 ermaro...@gmail.com wrote: > > Hello, > > I'm currently working with the DEM-Engine for simulating granular flow, > similar to the scenario in DEMO_Hopper_Cylinder_sphere. In this demo, the > generated CSV files include data on position, radius, velocity, and family > for each particle. What i want to do is to add contact forces : > Specifically, for any given particle (let's call it Particle A), I want to > identify all particles in contact with it, record the force exerted by each > contacting particle, and include this information on the same dedicated > line of the CSV file for Particle A. Is there an existing method or > approach that would allow me to achieve this? > > Thank you! > > Marouane ELBISSOURI > > -- You received this message because you are subscribed to the Google Groups "ProjectChrono" group. To unsubscribe from this group and stop receiving emails from it, send an email to projectchrono+unsubscr...@googlegroups.com. To view this discussion visit https://groups.google.com/d/msgid/projectchrono/867a090e-5e22-4f47-ab1e-1fbbaa62161dn%40googlegroups.com.
