Hi Sumaya, I think you’ve essentially already described the difference between *DP* and *DPSimplified*. Running the full *DP* demo is a major task. It requires a prerequisite run and is computationally expensive. I created *DPSimplified* to provide a more accessible drawbar-pull example. In this version, the particles are larger, resulting in fewer total particles and faster runs. This terrain representation still captures the overall terrain response characteristics similar to GRC-1.
Regarding your comments on the types of simulations you want and where to begin, I’d like to clarify that it’s *not* about creating two-sphere clumps and hoping that they somehow represent *GRC-1* in the simulation. Rather, you need to construct a terrain representation that meets your specific needs and then verify that it does. With that said, you can start with *WheelDP*. It’s smaller, easier to modify, and overall simpler to work with. However, keep in mind that you cannot easily modify the checkpoint files if you use *WheelDP*. These files contain pre-settled particle beds, and naively changing particle sizes will lead to inconsistent scenes (e.g., large overlaps if particles are enlarged), which will cause divergence in subsequent simulations. If you wish to change particle shapes or sizes, you must modify the initial configuration, re-run the settling process to generate new checkpoint files, and then use those. Also note that you don’t change particle sizes within the checkpoint file; you do so in the *clump template* within your test scripts. Of course, you could write a custom script that reads particle sizes and shapes from an external file; that’s entirely up to you. DEM-Engine is a *core solver*, not a tightly constrained end-user application yet. Lastly, for the *DPs* test, I wouldn’t call those parameters “inputs.” It’s simply a test designed to measure the drawbar-pull ratio of a wheel shape, given predefined wheel angular velocity and slip ratio (*TR*). Thank you, Ruochun On Wednesday, October 29, 2025 at 4:48:40 AM UTC+8 sumaya wrote: > Hi, > > I wanted to understand the exact differences between the WheelDP > executable and the WheelDP_simplified version. > > From my experience: > > WheelDP_simplified simulates a relatively small number of particles (for > me, it generated around 26K particles). > > WheelDP simulates a very large number of particles (for me, it generated > around 4.68 million particles). > > My understanding is that the WheelDP version uses GRC-1 simulant, while > nothing specific is mentioned for the simplified version, except that the > number of particles is based on the simulation box size and then scaled. > Could you please clarify what other differences exist between these two > executables? > > For my research, I want to simulate 6 mm particles (around 300,000 > particles in total) for a drawbar-pull test. The particles will be > spherical clumps of 2(not three), and the simulant should preferably be > lunar simulant (GRC-1). Which executable would you recommend for this > scenario: WheelDP or WheelDP_simplified? > > Additionally, I want to confirm that for the WheelDP test, it takes wheel > rotational speed and horizontal velocity as inputs and provides > drawbar-pull force as output. Could you please verify this? > > If I choose to use the WheelDP executable, where should I modify the > particle size, and do I also need to modify the particle numbers in the > GRC-1 and GRC-2 files? > > Thank you for your guidance. > > Best regards, -- 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 visit https://groups.google.com/d/msgid/projectchrono/06cb6c19-9811-4811-a5c9-926573afacebn%40googlegroups.com.
