How to achieve perfectly flat, mirrorlike water surface.

[RobH22]

I'm not very expereinced with Phoenix yet but I have a client who wants a perfect mirror water surface and to see a gliding bird just touch one talon in the surface and drag it. I can't seem to get the water to ever flatten out. I keep simulating longer and longer just to get to a flat state but that takes hours. I've turned 'Motion Inerta' and 'Air Effects' off. I don't have any wind in the scene anyway.

I know I'm getting some ripples from the sides of the container and I can make that much wider, but that's more particles to calculate.

Is there a way I can just get absolutely flat water at frame 0 so I can then bring in my dragging object?

[slavina.nikolova]

Hey,

How about filling the Grid with Initial Fill Up - this will fill the grid with water from the first frame.
You could try increasing the Scene Scale - this way the gravity will not pull down the particles a huge distance on each frame and the solver would be able to stabilize them and keep the surface smooth.
Another option is to increase the Steps Per Frame - the result will be the same as above. It is important to mention that this can increase the simulation time, so it is good to experiment with the option and choose a value that works best in your case.
To see how the water settles, you will probably need to simulate some additional frames.


Hope this helps!

[Svetlin.Nikolov]

Please also note that there is always going to be some movement in the liquid solver - it's rarely the case when a solver is needed but the final result would be standing still. If you need to freeze the particles, you could use a Drag force, or a Particle Tuner to force the velocity to zero. In the tuner you could create a condition that describes which particles should be frozen.

Cheers!

[RobH22]

Thanks Slavina. That's what I am doing but the fluid seems to push off of the sides and bottom. However, I've found that if I use some 'Mesh Smoothing' in the 'Rendering' section I can get it pretty flat. I'm going to try to increase the Scene Scale as you suggest. I think that is a good suggestion as well as the 'Steps per Frame.' I already have been using that but I think I can go up more. I appreciate your suggestions, I'm slowly getting there.

What I can't now get is the small wavelets to keep rolling away. I'm dragging an object in a linear way in a straight line so that it just breaks the surface and creates a small wavelet "V" in the water. Sort of the like the Paramount Pictures movie opening logo where the star drags in the water. I want to have that wavelet that forms a "V" behind the object to just keep moving away and getting wider and wider like it would in real life. But mine is turbulent and it just dissipates. I can't figure out how to keep it moving away and from dissapating. I reduced 'Gravity' but that didn't really help. And I think the 'Mesh Smoothing' I do above might be killing what I'm trying to achieve. As is always with these, we dive into them for a client and try to learn the tool at the same time. I'm not achieving what I thought I was going to be able to fast enough. Thanks again for your help.

[RobH22]

Please also note that there is always going to be some movement in the liquid solver - it's rarely the case when a solver is needed but the final result would be standing still. If you need to freeze the particles, you could use a Drag force, or a Particle Tuner to force the velocity to zero. In the tuner you could create a condition that describes which particles should be frozen.

Cheers!

That's a good thought Svetlin. Once frozen, can I animate that and 'Unfreeze' it because after it's flat, I need to form wavelets from the object just touching and dragging? In some particle simulations you can simulate to a point where everything is where you want and it and then tell the code that is your new '0' point. Say I animate to frame 300 and things are nice and flat. Can I now tell Phoenix to ignore frames 0-299 and always start at 300? I have not been able to find a setting like that.

[slavina.nikolova]

Hey,

-> For the small wavelet "V" in the water, you could try increasing the Motion Velocity Effect of the object you are using. If you right-click in the viewport when the objects is selected, you will find the Phoenix Properties menu, there you will see the Motion Velocity Effect option. This option allows you to control the impact of a moving object over the fluid. Try different values to see how the object will affect the liquid. Here you can find more info about the Phoenix Properties menu - https://docs.chaos.com/display/PHX4M...ode+Properties

-> The Particle and Voxel Tuners are affecting the simulation until the condition you set is fulfilled, so you could adjust the Particle Tuner to affect only the particles that are fulfilling the condition. You could do it by using the Particle Age Channel, for example. Lets say that you need the particles to be frozen until Frame 9. In this case, the condition will be:

If the Age is Less Than 0,3 (0.1 is equal to 3 frames, so 0,3 is equal to 9 frames),
Then Set the Velocity to 0.
This means that the liquid particles with Age under 0.3 (9 frames) will have Velocity set to 0 and as soon as their Ages is greater than 0,3, they won't be freezed anymore.

It's important to mention that you will need to enable the Particle Age Channel from the Output rollout, if you want to use it in the Particle Tuner condition.
Here you can find more information and examples about the Particle Tuner - https://docs.chaos.com/display/PHX4MAX/Particle+Tuner

-> As for the starting point of the simulation, you could try Simulation rollout -> Start Frame -> disable Timeline -> set a custom Start Frame - https://docs.chaos.com/display/PHX4M...ion-Parameters


Hope this helps!

[RobH22]

Slavina, this is exactly what I was looking for, some wisdom from someone who knows more of the subtlities of the simulation settings. I don't mind researching and reading but sometimes don't know which direction to start in. You've given me a lot to start with here and it will help me not only finish this little project but it will help me get better with Phoenix overall.

Thank you...

Rob