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Hello there!

I'm trying to create a ship sailing effect on Houdini 17.5 (with Guided Ocean Layer tool). But I'm having lot of issue.

- First of all, as you can see on flipbook, I have lot of particles popping up from ship sides. Why it happens? Can't figure out how avoid this problem.

- I used the Deforming Object shelf tool for simulating the ship as volume source. However if I choose Volume as Velocity Type on Flip Solver > Volume Motion > Collisions tab, it looks like fluid doesn't interact well with my geo. Basically I have not splashes, even if I select "Use Volume Velocity for Collision" on Flip Object > Collisions. So I need to switch on Point velocity Type in order for me to have good results. Is that a correct way even if my collision source is a Volume? Is it better to treat collision geometry as volume or mesh?

- Is there a way to avoid splashes to slide on surface? I tried to increase the Velocity Blend (on Flip Solver > Particles Motion > Droplets) with no results.

- Lastly, I'd like to achieve a good results regarding wave trails (see pictures). Basically I have too rounded and large waves from the ship prow. I'd live to have more V Shaped waves. My scene is more or less in real scale (meters). I used a 0.8 Time Scale value in FLIP Solver in order for me to have good trails, but cannot achieve the desired result.


Any help will be really appreciated. Thank you so much for your time.







Edited by mois23

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I think the popping comes from your ships shape. It got those things on the side catching the water and blowing it away. give it a try and remove them. I'm not an expert with ships, but I've never seen something like this. Would someone build such a non hydrodynamic ship?

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I tried to fix the shape and keep just the main body, but problem still remains. I did several research (Read Here and Here) and it seems like the main problem is the Reseeding and my geo Velocity Speed. According to Houdini documentation:

Setting the various Reseeding values too high can lead to fluid gaining volume over time in very splashy fluid simulations. Decreasing the Particle Radius Scale or the Death Threshold can reduce the volume by causing overcrowded voxels to be pruned earlier. Decreasing the amount and/or bandwidth of Surface Oversampling can help alleviate this problem as well.

And also:

Reseeding can help avoid collapsing pockets of air forming in the fluid near collisions

I'll play around with all reseeding settings and I'll share some results. However, if I disable the Reseeding (as they did in the links above) my ocean shapes collapse. Why this happens? Should Reseeding just populate the shape with more particles?


Furthermore, with "Collision detection: Particles" I have good noisy waves but simulation becomes a mess over time. With "Collision detection: Move outside collision" I have a more stable simulation, but too smooth waves and crazy particles flying away. Can't understand the main difference (documentation it's not clear enough).


Really? No one can help me??


Annotation 2019-10-11 095013.png

Edited by mois23

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havent see this post before, you can make wake forces instead collision for more control, collision ships is more complicated about the results as you want, also you can make mixed collison less velocity and wake force .


hope helps 


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