Strong Surface mode

[ttdww]

regarding scale, that's a significant param as i'm sure you're aware. a wedge test with different scene scales goes a long way, however i've found thus far that Chaos has it tied to real world scale versus behavior very well.

[Ivaylo Katev]

this is an expected problem with very high res. to keep proper behavior you have to increase the spf when increase the resolution, otherwise unnatural waves appear and the surface becomes blobby. that's why we are focused on the flip solver, it does not need to increase the spf and therefore is better for high res simulations. however, it still has no foam and i suppose you will need foam over the river. for now try to increase the spf, and i will attract the coworker who made this scene to the discussion.

[magilla]

I have no idea what a wedge test is but my scene is set up to real world scale

[ttdww]

ah sorry. a small set of sims with differing values starting from low to high. in this case, low scale to high scale to see the different results you get - that is, if the other params aren't resolving the issue. if they are, i'd stick with real world scale for your river.

[magilla]

so I shouldn't need Strong surface mode on if I just increase the spf?

[Ivaylo Katev]

yes, if you increase the spf there is no need of strong surface.
let me explain more about this problem. actually it is related to the advection, the stage that moves the liquid in the grid. if for single simulation step the liquid travels too big distance, the simulation tends to form artificial waves and the liquid surface is disturbed. the solution is simple - increase the spf, this will decrease the distance traveled in single step and the simulation will get smoother. however, this is leads to longer simulation times. if you increase the spf twice, the simulation time will be doubled. so, keep it as low as possible. perhaps you have to make initial tests with shorter grid, that covers only the starting point of the liquid, and when you find the best spf, you can extend it to the desired size.

[tsetso]

hi,

as @ttdww mentioned it's a good idea to work in realscale. In the video that I made the riverbed is 22m long, 9m wide and 7m high.

What I did in the Liquids tab is I've turned off the: Wetting, Static surfaces correction and Strong surface mode.
I've enabled the "Initial fillup" in order to have the riverbed full of water in the first frame (no need to wait for the emitter to fill the entire riverbed).

And also decreased the Sharpness to 0.5



As for the dynamics: Symmetric conservation with quality of 30 and Classic advection with SPF: 2.0 is fine.
Here's the parameters. I'm also working on a tutorial for the River now, so you'll be able to watch it soon.


Regards,
Tsetso

[magilla]

thanks Tsetso - awesome work. I think the sharpness might be the key.