Hi Wenxuan, To understand that, it's better to refer to the DEM-Engine paper <https://www.sciencedirect.com/science/article/pii/S001046552400119X>. It lets you know approximately, how large a "margin" or envelope is added to spheres/other simulation entities to account for potential future contacts. If you see it's too large then it may negatively impact the performance due to introducing too many false positive contacts. In general, this piece of info is not super critical for an average user.
You can import a one-layer surface mesh. But know that the mesh is directional, and non-physical things will happen if the particles come in contact with the mesh incorrectly, namely from the "inside" direction. Thank you, Ruochun On Saturday, September 14, 2024 at 3:46:17 PM UTC+8 [email protected] wrote: > Hi, Ruochun > > Thank you for your reply. How to understand the prompts on the > console “To give an example, all geometries may be enlarged/thickened by > around 0.0008 (estimated with the initial step size, initial update > frequency and velocity 1) for contact detection purpose. > This in the case of the smallest sphere, means enlarging radius by > 3.90273%.” when running the DEMdemo_Repose? In addition, can I import a > surface-meshed funnel.obj file (a.k.a The funnel wall has no thickness). > > Best regards > Wenxuan > > 在2024年9月13日星期五 UTC+8 19:22:55<Ruochun Zhang> 写道： > >> This is because *sphere_template *is a *shared_ptr*. So in your example, >> you simply modified the same *sphere_template *10 times and only the >> final modification will be used in the initialization step. You may want to >> *Duplicate >> sphere_template *first (creating a copy) before using it in *AddClumps*. >> See an example of *Duplicate *in *DEMdemo_GRCPrep_Part1.cpp*. >> >> Thank you, >> Ruochun >> >> On Friday, September 13, 2024 at 5:13:34 PM UTC+8 [email protected] >> wrote: >> >>> Hi, Ruochun >>> >>> I want to use Scale function to generator different size of >>> particle，but it doesn't work fine, the diameter of 10 particles generated >>> is same. >>> double scale_par[10] = {0.9, 0.92 * 0.9, 0.94, 0.96, 0.98, 1, 1.02, 1.04, >>> 1.06, 1.08}; >>> double pos_x[10] = {4, 4.1, 4.2, 4.3, 4.4, 4.5, 4.6, 4.7, 4.8, 4.9}; >>> double pos_y[10] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0}; >>> double pos_z[10] = {14, 14, 14, 14, 14, 14, 14, 14, 14, 14}; >>> >>> for (unsigned int i = 0; i < 10; i++) >>> { >>> sphere_template->Scale(scale_par[i]); >>> DEMSim.AddClumps(sphere_template, make_float3(pos_x[i], pos_y[i], pos_z[ >>> i])); >>> } >>> >>> Best regards, >>> Wenxuan >>> >>> >>> 在2024年9月13日星期五 UTC+8 16:07:09<Ruochun Zhang> 写道： >>> >>>> From what I understand, there are people trying similar things but >>>> there are no documents or working examples. It's in theory quite doable as >>>> DEME is designed for co-simulation, and you just write scripts that use >>>> DEME methods and OpenFOAM methods at the same time and that's it. If you >>>> are going to do it, you can use Chrono--DEME cosim examples >>>> <https://github.com/projectchrono/chrono-projects/tree/feature/DEME> >>>> here as inspiration. >>>> >>>> Thank you, >>>> Ruochun >>>> >>>> On Thursday, September 12, 2024 at 11:34:46 PM UTC+8 [email protected] >>>> wrote: >>>> >>>>> Hi, touching >>>>> >>>>> Thank you for your reply. By the way, >>>>> are there any examples of co-simulation about DEME coupling to >>>>> CFD(OpenFOAM)? >>>>> >>>>> Best regards, >>>>> Wenxuan >>>>> Ruochun Zhang <[email protected]>于2024年9月12日 周四23:16写道： >>>>> >>>>>> In general, it should affect the efficiency insignificantly, since if >>>>>> you have too many templates (aka too many types of mass properties), the >>>>>> solver should automatically give up grouping and storing based on >>>>>> templates, and just store individual clump's mass properties. If you are >>>>>> very concerned then you can call *DisableJitifyMassProperties *to >>>>>> force this behavior. >>>>>> >>>>>> I don't feel I understand what you meant by "group the particles" >>>>>> based on their size ranges. Maybe you want to make sure that when you >>>>>> sample initial particles in a certain region, they fall into a specific >>>>>> range. In that case, you might store templates that resemble a range, >>>>>> say >>>>>> [2, 4], in a standalone vector. Then when sampling a region in your >>>>>> simulation domain, you pick templates only from this vector. >>>>>> >>>>>> Thank you, >>>>>> Ruochun >>>>>> >>>>>> On Thursday, September 12, 2024 at 12:56:24 PM UTC+8 >>>>>> [email protected] wrote: >>>>>> >>>>>>> Hi, Ruochun >>>>>>> >>>>>>> 1. If so many spherical particle templates are created, will >>>>>>> it affect the calculation speed? >>>>>>> 2. If I have particles with multiple particle size ranges, >>>>>>> such as [2 mm, 4mm], [4 mm, 6 mm], [6 mm, 8 mm], how can I group the >>>>>>> particles based on their particle size ranges? >>>>>>> >>>>>>> Thank you >>>>>>> Wenxuan >>>>>>> >>>>>>> 在2024年9月12日星期四 UTC+8 08:18:51<Ruochun Zhang> 写道： >>>>>>> >>>>>>>> Hi Wenxuan, >>>>>>>> >>>>>>>> You can use DEMdemo_BallDrop.cpp >>>>>>>> <https://github.com/projectchrono/DEM-Engine/blob/main/src/demo/DEMdemo_BallDrop.cpp> >>>>>>>> as >>>>>>>> an example and starting point. There, I created 11 templates with >>>>>>>> diameters >>>>>>>> ranging from 0.25cm to 0.35cm, then when instantiating particles, they >>>>>>>> randomly took one of the 11 templates. This is usually enough for >>>>>>>> emulating >>>>>>>> a size distribution. >>>>>>>> >>>>>>>> However, if you want "truly random" distribution in the range of [8 >>>>>>>> mm, 12mm], then you probably just have to generate random floating >>>>>>>> numbers >>>>>>>> in this range, then create a sphere template based on this number, >>>>>>>> then >>>>>>>> create a particle using this template, then repeat the process. In the >>>>>>>> end, >>>>>>>> you will have as many templates as particles, and each of them is >>>>>>>> different. DEME should support this as well (and if it complains, >>>>>>>> please >>>>>>>> let me know). From the simulation physics point of view, this is >>>>>>>> likely an >>>>>>>> overkill. >>>>>>>> >>>>>>>> Thank you, >>>>>>>> Ruochun >>>>>>>> >>>>>>>> On Wednesday, September 11, 2024 at 10:26:07 AM UTC+8 >>>>>>>> [email protected] wrote: >>>>>>>> >>>>>>>>> Hi, Ruochun >>>>>>>>> >>>>>>>>> I got a sphere particle template through the LoadSphereType >>>>>>>>> function. The diameter of the sphere particle template is 10 mm. How >>>>>>>>> can I >>>>>>>>> add particles with a diameter randomly distributed in the range of [8 >>>>>>>>> mm, >>>>>>>>> 12mm] based on this spherical particle template? >>>>>>>>> >>>>>>>>> Best regards >>>>>>>>> Wenxuan XU >>>>>>>>> >>>>>>>> -- >>>>>> 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/36d78488-1e35-4c6a-8d93-56845e46b545n%40googlegroups.com >>>>>> >>>>>> <https://groups.google.com/d/msgid/projectchrono/36d78488-1e35-4c6a-8d93-56845e46b545n%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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