You can *SetVel *to simulation entities, such as particles, before the simulation starts. You can for example see how it is used at line 150 of *DEMdemo_GRCPrep_Part1*.
Thank you, Ruochun On Thursday, June 27, 2024 at 3:03:00 PM UTC+8 [email protected] wrote: > You are right. In fact, the scenario i would like to model is that the > impact of a rock block onto a palte after a freefall. I would like to set a > initial velocity for the rock block according to the freefall height. So, > how to set a initial velocity? > > Thank you, > Weigang > > On Thursday, June 27, 2024 at 12:54:00 PM UTC+8 Ruochun Zhang wrote: > >> That depends on whether we are on the same page about the concept of >> prescribing velocity. You understand that when the particles come in >> contact with the plate, they cannot keep whatever velocity you assigned >> them before, if you respect the contact force. So you either respect the >> contact force or do not respect it. By assigning a prescribed velocity to a >> family, you choose not to respect the contact force's influence on the >> entities, and always enforce this velocity. >> >> What I understand that you wish to achieve is to ensure the particles >> have a certain velocity at the moment they come in contact with the plate. >> That is not a velocity prescription. That can instead be done in some other >> ways. For example, initialize the simulation such that the particles are >> touching the plate, and give the particles an initial velocity then start >> the simulation. But I don't know if I understand what you wanted to do >> correctly, >> >> Thank you, >> Ruochun >> >> On Thursday, June 27, 2024 at 11:14:42 AM UTC+8 [email protected] >> wrote: >> >>> Hi Ruochun, >>> >>> After removing the line which prescribe the linear motion, the particles >>> can contact with the plate. However, if we have to prescribe a velocity for >>> the particles, where should we add this line? >>> >>> Thank you, >>> Weigang >>> >>> On Friday, June 21, 2024 at 3:12:06 PM UTC+8 Ruochun Zhang wrote: >>> >>>> Hi Weigang, >>>> >>>> This is because you prescribed the linear motion of family 1 (which is >>>> for all the particles) to be -1.0. When the velocity is prescribed, the >>>> simulation entities won't accept the influence of physical contacts, and >>>> will keep the prescribed velocity no matter what. This is exactly what we >>>> see in the simulation. Removing that line should fix it. You probably >>>> meant >>>> to add an initial velocity. >>>> >>>> Ruochun >>>> >>>> >>>> >>>> On Friday, June 21, 2024 at 9:05:11 AM UTC+8 [email protected] wrote: >>>> >>>>> Hi Ruochun: >>>>> >>>>> The script is attached below. >>>>> >>>>> Thank you, >>>>> Weigang >>>>> >>>>> On Thursday, June 20, 2024 at 7:27:35 PM UTC+8 Ruochun Zhang wrote: >>>>> >>>>>> I assume you are doing it via a custom force model. In that case, >>>>>> this problem is very similar to the exact demo we provided (which runs). >>>>>> You have to tell us what you changed in order for us to give suggestions. >>>>>> >>>>>> Thank you, >>>>>> Ruochun >>>>>> >>>>>> On Thursday, June 20, 2024 at 6:55:10 PM UTC+8 [email protected] >>>>>> wrote: >>>>>> >>>>>>> Hi Ruochun, >>>>>>> >>>>>>> I am currently modelling the impact of a rock block against a plate. >>>>>>> However, as shown below, the spheres penetrate through the plate >>>>>>> without >>>>>>> any contact with the plate. Could you give some suggestions? >>>>>>> [image: 微信图片_20240620185350.jpg] >>>>>>> >>>>>>> Thank you, >>>>>>> Weigang >>>>>>> >>>>>>> On Thursday, June 20, 2024 at 5:02:38 PM UTC+8 Ruochun Zhang wrote: >>>>>>> >>>>>>>> Hi Weigang, >>>>>>>> >>>>>>>> Yes. And that's exactly what we did in the fracture demo to begin >>>>>>>> with, is it not? >>>>>>>> >>>>>>>> Thank you, >>>>>>>> Ruochun >>>>>>>> >>>>>>>> On Thursday, June 20, 2024 at 3:07:07 PM UTC+8 [email protected] >>>>>>>> wrote: >>>>>>>> >>>>>>>>> Hi Ruochun, >>>>>>>>> >>>>>>>>> Do you mean that we can add a if statements in the >>>>>>>>> ForceModelWithFracture.cu to differentiate types of contacts? >>>>>>>>> >>>>>>>>> Thank you, >>>>>>>>> Weigang >>>>>>>>> >>>>>>>>> >>>>>>>>> >>>>>>>>> On Thursday, June 13, 2024 at 8:30:45 PM UTC+8 Ruochun Zhang wrote: >>>>>>>>> >>>>>>>>>> Currently, DEM-Engine custom model functionality permits only one >>>>>>>>>> script, meaning that in principal, you are writing a unified force >>>>>>>>>> model >>>>>>>>>> that goes for sphere-sphere, sphere-boundary, *and *sphere-mesh. >>>>>>>>>> Just think of the sphere-compressor contact as a special case, which >>>>>>>>>> is the >>>>>>>>>> contact between a normal sphere and an infinitely-large sphere. >>>>>>>>>> >>>>>>>>>> About enforcing different models for different objects, you can >>>>>>>>>> associate different objects with respective family numbers, then use >>>>>>>>>> if >>>>>>>>>> statements to differentiate types of contacts. I talked about this >>>>>>>>>> in one >>>>>>>>>> of the earlier replies in this thread, please go back and have a >>>>>>>>>> look. >>>>>>>>>> >>>>>>>>>> Thank you, >>>>>>>>>> Ruochun >>>>>>>>>> >>>>>>>>>> >>>>>>>>>> On Thursday, June 13, 2024 at 1:31:37 PM UTC+8 >>>>>>>>>> [email protected] wrote: >>>>>>>>>> >>>>>>>>>>> Hi Ruochun, >>>>>>>>>>> >>>>>>>>>>> Thank you for your reply. In fact, I am puzzled that there is >>>>>>>>>>> not any sentence in the Fracture-Box demo to declare the contact >>>>>>>>>>> model >>>>>>>>>>> between spheres and the compressing plate. So, how to declare the >>>>>>>>>>> contact >>>>>>>>>>> model, especially for the case in which there has been another >>>>>>>>>>> contact >>>>>>>>>>> model, such as the ForceModelWithFracture.cu? >>>>>>>>>>> >>>>>>>>>>> Thank you, >>>>>>>>>>> Weigang >>>>>>>>>>> >>>>>>>>>>> On Thursday, June 13, 2024 at 12:03:52 AM UTC+8 Ruochun Zhang >>>>>>>>>>> wrote: >>>>>>>>>>> >>>>>>>>>>>> Hi Weigang, >>>>>>>>>>>> >>>>>>>>>>>> Note that in general, if you use a custom force model, then >>>>>>>>>>>> that model alone is used, there is no fallback so I wouldn't call >>>>>>>>>>>> that >>>>>>>>>>>> anything has "defaulted" to Hertz–Mindlin. Specific to the >>>>>>>>>>>> Fracture-Box >>>>>>>>>>>> demo, it's just that the force model (ForceModelWithFracture.cu) >>>>>>>>>>>> is written >>>>>>>>>>>> in a way that when the bond between two particles breaks, the >>>>>>>>>>>> "else" branch >>>>>>>>>>>> of that big if statement is executed, and something similar to >>>>>>>>>>>> Hertz–Mindlin is enforced. >>>>>>>>>>>> >>>>>>>>>>>> I said it's similar since it's not a pure spring–damper model >>>>>>>>>>>> now, it's a spring–damper model with the resting location >>>>>>>>>>>> (zero-force >>>>>>>>>>>> location) being the penetration depth the moment when the bond >>>>>>>>>>>> broke. This >>>>>>>>>>>> implementation avoids a potential problem with a pure >>>>>>>>>>>> spring–damper model: >>>>>>>>>>>> Without the adjusted resting location, a newly broken-away pair of >>>>>>>>>>>> particles would see the bond suddenly gone but there were still >>>>>>>>>>>> left-over >>>>>>>>>>>> penetration, therefore immediately pushing each other away with >>>>>>>>>>>> high >>>>>>>>>>>> velocity, resulting in non-physical results. Shout-out to Bona for >>>>>>>>>>>> implementing this. >>>>>>>>>>>> >>>>>>>>>>>> Thank you! >>>>>>>>>>>> Ruochun >>>>>>>>>>>> >>>>>>>>>>>> >>>>>>>>>>>> On Wednesday, June 12, 2024 at 8:33:55 PM UTC+8 >>>>>>>>>>>> [email protected] wrote: >>>>>>>>>>>> >>>>>>>>>>>>> Hi Ruochun, >>>>>>>>>>>>> >>>>>>>>>>>>> Thank you for your great work. The demo now is runs well. I >>>>>>>>>>>>> have a question about the Fracture-Box demo. After the bond >>>>>>>>>>>>> between two >>>>>>>>>>>>> particles breaks, is it right that the contact model between them >>>>>>>>>>>>> change >>>>>>>>>>>>> defaultly from ForceModelWithFracture to Hertz–Mindlin model? >>>>>>>>>>>>> >>>>>>>>>>>>> Thank you, >>>>>>>>>>>>> Weigang >>>>>>>>>>>>> >>>>>>>>>>>>> On Friday, May 31, 2024 at 8:05:24 PM UTC+8 Ruochun Zhang >>>>>>>>>>>>> wrote: >>>>>>>>>>>>> >>>>>>>>>>>>>> Hi Weigang, >>>>>>>>>>>>>> >>>>>>>>>>>>>> The problem appears to be fixed now. Please pull the newest >>>>>>>>>>>>>> main branch and try the fracture demo again. I suggest you do a >>>>>>>>>>>>>> clean >>>>>>>>>>>>>> rebuild from an empty directory, because only a force model file >>>>>>>>>>>>>> is changed >>>>>>>>>>>>>> and if you just "make", cmake probably thinks nothing needs to >>>>>>>>>>>>>> be done. Or >>>>>>>>>>>>>> you can simply manually copy the modified cu file over to the >>>>>>>>>>>>>> appropriate >>>>>>>>>>>>>> location in the build folder. >>>>>>>>>>>>>> >>>>>>>>>>>>>> The problem was that we left an uninitialized variable in the >>>>>>>>>>>>>> force model file. On data center cards, the compiler zeros it >>>>>>>>>>>>>> out >>>>>>>>>>>>>> automatically, but on consumer cards it does not. We therefore >>>>>>>>>>>>>> missed it >>>>>>>>>>>>>> initially. Should be all good now. >>>>>>>>>>>>>> >>>>>>>>>>>>>> Thank you, >>>>>>>>>>>>>> Ruochun >>>>>>>>>>>>>> >>>>>>>>>>>>>> >>>>>>>>>>>>>> On Tue, May 28, 2024, 11:00 PM Ruochun Zhang < >>>>>>>>>>>>>> [email protected]> wrote: >>>>>>>>>>>>>> >>>>>>>>>>>>>>> Hi Weigang, >>>>>>>>>>>>>>> >>>>>>>>>>>>>>> It's not like recommending a card; rather, if you happen to >>>>>>>>>>>>>>> have a data center card available (A100, A5000 etc.), you can >>>>>>>>>>>>>>> circumvent >>>>>>>>>>>>>>> this problem for now by using them. Otherwise, let's hope we >>>>>>>>>>>>>>> find a >>>>>>>>>>>>>>> solution very soon, or at least find a workaround. We'll keep >>>>>>>>>>>>>>> you posted. >>>>>>>>>>>>>>> >>>>>>>>>>>>>>> Thank you, >>>>>>>>>>>>>>> Ruochun >>>>>>>>>>>>>>> >>>>>>>>>>>>>>> On Monday, May 27, 2024 at 7:27:10 PM UTC+8 >>>>>>>>>>>>>>> [email protected] wrote: >>>>>>>>>>>>>>> >>>>>>>>>>>>>>>> Hi Ruochun, >>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>> My card is indeed a gaming card NVIDIA GeForce RTX 2070 >>>>>>>>>>>>>>>> Super. Could you recommend a card? >>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>> Thanks, >>>>>>>>>>>>>>>> Weigang >>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>> On Saturday, May 25, 2024 at 10:44:17 PM UTC+8 Ruochun >>>>>>>>>>>>>>>> Zhang wrote: >>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>> Hi Weigang, >>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>> I would like to answer Question 2 first. You can use >>>>>>>>>>>>>>>>> variables *AOwnerFamily *and *BOwnerFamily *to refer to >>>>>>>>>>>>>>>>> clump (or owner) A's and clump B's family numbers directly in >>>>>>>>>>>>>>>>> the force >>>>>>>>>>>>>>>>> model. So you can write *if *statements that treat each >>>>>>>>>>>>>>>>> case accordingly. This is mentioned in the DEME paper: You >>>>>>>>>>>>>>>>> can check out >>>>>>>>>>>>>>>>> Table 2. >>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>> For Question 1, the situation is more complicated. We are >>>>>>>>>>>>>>>>> actually able to reproduce the problem you encountered >>>>>>>>>>>>>>>>> (simulation >>>>>>>>>>>>>>>>> freezing), but on consumer/gaming cards only. It runs >>>>>>>>>>>>>>>>> perfectly on data >>>>>>>>>>>>>>>>> center cards and that's what we used for generating this >>>>>>>>>>>>>>>>> experiment, >>>>>>>>>>>>>>>>> therefore it did not appear a problem for us. It's likely due >>>>>>>>>>>>>>>>> to different >>>>>>>>>>>>>>>>> GPU architectures running the same code differently, we'll >>>>>>>>>>>>>>>>> try to find a >>>>>>>>>>>>>>>>> solution and let you know in the following days, so stay >>>>>>>>>>>>>>>>> tuned. By the way, >>>>>>>>>>>>>>>>> you are using a gaming card to run the simulations, correct? >>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>> Thank you, >>>>>>>>>>>>>>>>> Ruochun >>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>> On Friday, May 24, 2024 at 8:47:00 AM UTC+8 >>>>>>>>>>>>>>>>> [email protected] wrote: >>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>> Thank you for your reply! I have two questions about the >>>>>>>>>>>>>>>>>> demo "DEMdemo-Fracture-Box". >>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>> (1) After i have run this demo for one day, there is >>>>>>>>>>>>>>>>>> still nothing outputed. Is it fact that the DEME will run a >>>>>>>>>>>>>>>>>> long time once >>>>>>>>>>>>>>>>>> a fracture model is used? >>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>> (2) How to tell DEME the contact force models between >>>>>>>>>>>>>>>>>> different familys? I did not see any snippet which >>>>>>>>>>>>>>>>>> undertakes this work, >>>>>>>>>>>>>>>>>> although the demo has at least two kinds of contact force >>>>>>>>>>>>>>>>>> model. The >>>>>>>>>>>>>>>>>> question i really want to ask is that, if we have more than >>>>>>>>>>>>>>>>>> three familys >>>>>>>>>>>>>>>>>> in our model and there are more than two familys consist of >>>>>>>>>>>>>>>>>> spherical >>>>>>>>>>>>>>>>>> particles, how to tell DEME the contact force model between >>>>>>>>>>>>>>>>>> different >>>>>>>>>>>>>>>>>> familys, and tell DEME the contact force model between the >>>>>>>>>>>>>>>>>> particles of a >>>>>>>>>>>>>>>>>> family in the same time. >>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>> Thank you, >>>>>>>>>>>>>>>>>> Weigang >>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>> On Thursday, May 23, 2024 at 10:10:14 PM UTC+8 Ruochun >>>>>>>>>>>>>>>>>> Zhang wrote: >>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>> No. That's because the *sphere components* in a clump >>>>>>>>>>>>>>>>>>> are just shape representations, and they have no physics, >>>>>>>>>>>>>>>>>>> only material >>>>>>>>>>>>>>>>>>> properties. If they did have interaction with each other >>>>>>>>>>>>>>>>>>> then every clump >>>>>>>>>>>>>>>>>>> would've immediately exploded upon simulation starting. >>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>> Thank you, >>>>>>>>>>>>>>>>>>> Ruochun >>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>> On Thursday, May 23, 2024 at 12:16:32 PM UTC+8 >>>>>>>>>>>>>>>>>>> [email protected] wrote: >>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>> Hi Ruochun, >>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>> Thank you for your reply! I have a question about the >>>>>>>>>>>>>>>>>>>> clump. Do the particles in a clump interact with each >>>>>>>>>>>>>>>>>>>> other via any force >>>>>>>>>>>>>>>>>>>> model? >>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>> Thank you, >>>>>>>>>>>>>>>>>>>> Weigang >>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>> On Monday, May 20, 2024 at 10:26:03 PM UTC+8 Ruochun >>>>>>>>>>>>>>>>>>>> Zhang wrote: >>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>> Hi Weigang, >>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>> Yes. Again, DEME only cares about the position and >>>>>>>>>>>>>>>>>>>>> radius of the initial spheres, so you can supply it >>>>>>>>>>>>>>>>>>>>> however you want. If >>>>>>>>>>>>>>>>>>>>> you have a file that records this information using your >>>>>>>>>>>>>>>>>>>>> own format, then >>>>>>>>>>>>>>>>>>>>> the easiest thing is to have your own C++ or Python >>>>>>>>>>>>>>>>>>>>> script that reads it >>>>>>>>>>>>>>>>>>>>> into arrays and then feeds them to the solver. If >>>>>>>>>>>>>>>>>>>>> your file shares the format with DEME's standard clump >>>>>>>>>>>>>>>>>>>>> output file, or your >>>>>>>>>>>>>>>>>>>>> file is simply the output of *WriteClumpFile*, then >>>>>>>>>>>>>>>>>>>>> you can conveniently load clump positions and >>>>>>>>>>>>>>>>>>>>> orientations by *ReadClumpXyzFromCsv >>>>>>>>>>>>>>>>>>>>> *and *ReadClumpQuatFromCsv *(examples are in >>>>>>>>>>>>>>>>>>>>> GRCPrep_Part1 and 2). Note that currently, sphere radius >>>>>>>>>>>>>>>>>>>>> cannot be read >>>>>>>>>>>>>>>>>>>>> from standard clump output files since it's part of the >>>>>>>>>>>>>>>>>>>>> clump template >>>>>>>>>>>>>>>>>>>>> information thus not in the clump output. >>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>> Thank you, >>>>>>>>>>>>>>>>>>>>> Ruochun >>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>> On Monday, May 20, 2024 at 12:56:56 PM UTC+8 >>>>>>>>>>>>>>>>>>>>> [email protected] wrote: >>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>> Hi Everyone, >>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>> I would like to generate a block which consists of a >>>>>>>>>>>>>>>>>>>>>> assembly spheres. Is it possible to generate the block >>>>>>>>>>>>>>>>>>>>>> by other code, and >>>>>>>>>>>>>>>>>>>>>> then load it into DEM-Engine via a file containg the >>>>>>>>>>>>>>>>>>>>>> informations (such as >>>>>>>>>>>>>>>>>>>>>> position and radius) of the spheres? >>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>> Thank you, >>>>>>>>>>>>>>>>>>>>>> Weigang >>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>> -- >>>>>>>>>>>>>>> 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 [email protected]. >>>>>>>>>>>>>>> To view this discussion on the web visit >>>>>>>>>>>>>>> https://groups.google.com/d/msgid/projectchrono/1910af21-d1e3-43dd-a779-0c229e6150a6n%40googlegroups.com >>>>>>>>>>>>>>> >>>>>>>>>>>>>>> <https://groups.google.com/d/msgid/projectchrono/1910af21-d1e3-43dd-a779-0c229e6150a6n%40googlegroups.com?utm_medium=email&utm_source=footer> >>>>>>>>>>>>>>> . >>>>>>>>>>>>>>> >>>>>>>>>>>>>> -- You received this message because you are subscribed to the Google Groups "ProjectChrono" group. 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