bentway23 Posted December 2 Share Posted December 2 Alrighty, dealing with the perennial FLIP volume loss issue. Simple scene, just a rotating bottle. No volume loss at first, but once it turns sidewise and back it collapses. I've got the grid scale low and particle separation high (which stabilizes it at the beginning). This video is particle separation of 1.5 and 2/4 substeps, although lowering separation to 1 and substeps as high as 4/8 makes no difference, just takes longer to calculate. Reseeding is off, tried it with it oversampled which didn't help. Also tried as narrow band, same result. What am I missing? volloss.mp4 volloss.hiplc Quote Link to comment Share on other sites More sharing options...
hannes603 Posted December 2 Share Posted December 2 try gas equalize in dop. or you can use the flip object source to inject and update the volume on each frame Quote Link to comment Share on other sites More sharing options...
bentway23 Posted December 2 Author Share Posted December 2 Seems like using a source to keep injecting fluid is counter to a closed fluid sim. I'm all for faking it, but how would you know how much and when to emit? The gas equalize helps, but seems to only work through constant inflation. The end result is closer, but you can see in the beginning and end the whole liquid is rising. The add goal volume isn't keyframeable. This video is using an add goal of 1.5 (the example file's 62.5 was for a whole different scale and world). Is there a way to find a precise number to plug in there that does the trick, or is it just guesswork? I also tried 1.25 which didn't end up as close to the original, but even then still did the water-constantly-rising thing. vol_loss_gas_eq.mp4 Quote Link to comment Share on other sites More sharing options...
Atom Posted December 2 Share Posted December 2 (edited) Let's see if a discord link works... https://discord.com/channels/1169687778058047548/1179207481403121777/1313175362049671260 Edited December 2 by Atom Quote Link to comment Share on other sites More sharing options...
bentway23 Posted December 3 Author Share Posted December 3 Thanks for all the help! Found the solution: use MPM instead. Quote Link to comment Share on other sites More sharing options...
ryew Posted December 4 Share Posted December 4 On 12/2/2024 at 8:33 AM, Atom said: Let's see if a discord link works... https://discord.com/channels/1169687778058047548/1179207481403121777/1313175362049671260 Looks good, but not accessible for those of us who are not on Discord . . . . Quote Link to comment Share on other sites More sharing options...
Atom Posted December 5 Share Posted December 5 (edited) Here are both HIP files posted on Discord. It's interesting to see the MPM solution. It seems a little too bouncy, and if you let it settle, there is volume loss there as well. ap_volloss_120224.hiplc vol_loss_mpm_dc_12_2024.hiplc Edited December 5 by Atom 1 Quote Link to comment Share on other sites More sharing options...
ryew Posted December 5 Share Posted December 5 (edited) Thank you, Atom - very useful for comparison. To my recollection, it has always been reseeding that has been the go-to for attempting to address volume loss in FLIP but this problem has always been around and always been the bane of that FLIP sims as bentway23 notes in his original post, at least on these small-scale sims. With all the advancements since FLIP was first introduced, it's surprising to still have this nagging issue without a better soluation Edited December 5 by ryew Quote Link to comment Share on other sites More sharing options...
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