bluciensky Posted June 17, 2016 Share Posted June 17, 2016 (edited) I've done upresing the smoke-only simulation, but never done the pyro(with fuel field). When I tried to upres my explosion simulation, I get the similar shape/motion as my low res one, but not the same density/heat/temperature. I would assume it's because gasupres DOP doesn't have the 'gas released' parameter, which would work with my source volume and affect the initial density/temperature/heat of it. What am I missing in this work flow? Edited June 17, 2016 by bluciensky Quote Link to comment Share on other sites More sharing options...
fencer Posted June 17, 2016 Share Posted June 17, 2016 show the scene Quote Link to comment Share on other sites More sharing options...
bluciensky Posted June 17, 2016 Author Share Posted June 17, 2016 Um, I can't post hipfile Quote Link to comment Share on other sites More sharing options...
bunker Posted June 18, 2016 Share Posted June 18, 2016 It's definitely nothing to do with the lack of "gas released" in the upres solver."gas released" is controlling divergence on the lowers sim only - which affects the velocity at the projection stage The Upres solver copies the lowres vel field (and add some noise), there isn't any velocity projection. You shouldn't expect exactly the same amount of fire or smoke at the upres stage. For example, simply copying a lowres field into a hires grid isn't perfect (interpolation) during combustion any small error is carried across multiple fields over time, which make things worse. to simplify, combustion is: fuel∩temp>burn>heat>density you can see that any small error in the "fuel" field for example will affect the final products: heat/density some options to solve this issue: 1) adjust the heat/density values post sim (not the best result) 2) adjust some values in the upres combustion (very time consuming) 3) tweak the upres solver to bypass most of the combustion model: if you copy the burn field directly from the lowres sim, you don't need fuel and temperature, the result should be closer to your lowres. it's not perfect, but removes 2 fields and the error they introduce. You'll still need to tweak the combustion values a bit. ideally you would combine options 2 and 3, so you spend less time tweaking the combustion settings. hope that helps. 5 Quote Link to comment Share on other sites More sharing options...
bluciensky Posted June 23, 2016 Author Share Posted June 23, 2016 Thanks, Bunker, for your answer!! I realized I had some different valueson my Upres solver, after changing that, and tweaking a bit helped. Quote Link to comment Share on other sites More sharing options...
carlo_c Posted May 23, 2017 Share Posted May 23, 2017 On 2016-6-18 at 6:30 PM, bunker said: 3) tweak the upres solver to bypass most of the combustion model: if you copy the burn field directly from the lowres sim, you don't need fuel and temperature, the result should be closer to your lowres. it's not perfect, but removes 2 fields and the error they introduce. You'll still need to tweak the combustion values a bit. Hate to necro this thread but I'm just doing some upres tests and this is the only mention I can find of this, is there any chance you could elaborate a bit on the steps needed to tweak the upres solver. Just looking for another way to control my upres sim to match the low res closely Quote Link to comment Share on other sites More sharing options...
bunker Posted May 23, 2017 Share Posted May 23, 2017 Sure. The easiest way is to copy the fuel from lowres to upres 1 - save the fuel field in the lowres sim. 2 - on the upres solver, turn on "use lowres source resolution" and "source from imported fields". 3 - inside the upres solver, change the lowres_fuel and lowres_density fields type to "Scalar" (not Vector) -- I reported that bug so it might already be fixed in the latest build. also the border type on those fields should be "constant" (not Streak) same for lowres_vel hope that helps 2 Quote Link to comment Share on other sites More sharing options...
carlo_c Posted May 24, 2017 Share Posted May 24, 2017 (edited) Thanks for the reply bunker, I tried this with a default shelf tool fireball and then the shelf tool upres to test. This works great and is what I've previously been doing, but when I make the changes above I can't seem to get it to work properly. Probably just a silly mistake on my part, I've attached a hip file with it all set up if you or anyone else has a moment to spare upres_test.hiplc Edited May 24, 2017 by carlo_c forgot hip file :D Quote Link to comment Share on other sites More sharing options...
bunker Posted May 25, 2017 Share Posted May 25, 2017 you forgot the lowrestemperature field - it was still set as a vector field. The ramp parameters don't get referenced correctly from lowres to upres - you can copy the values manually for dissipation field and flames height (heat cool field) and the last thing, since you're using the lowres temperature field, you need to copy it back for visualization Have a look at the attached file upres_test_fix_bunker.hipnc 3 Quote Link to comment Share on other sites More sharing options...
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