Smooth ocean and a boat

[cb LLC]

Hi I have a scene with very calm water and a raft traveling. But for some reason I can clearly see borders and there is a bump in front of the grid. Am i doing anything wrong? is it phoenix limitation and I must have rough water to blend grid borders? Thanks

[georgi.zhekov]

Hello,

Your simulator is quite small - you can give it a bit more space around the vessel and increase the grid resolution a bit and the bump should be gone.
However for the borders you will need a bit of a rougher ocean surface to blend the seams. Also make sure to get a latest nightly build as we did some fixes for the blending with the ocean while you have smoothing enabled as is your case.

[cb LLC]

Hello,

Your simulator is quite small - you can give it a bit more space around the vessel and increase the grid resolution a bit and the bump should be gone.
However for the borders you will need a bit of a rougher ocean surface to blend the seams. Also make sure to get a latest nightly build as we did some fixes for the blending with the ocean while you have smoothing enabled as is your case.

Thank you
It is better with a newer build but the front still has water bump no matter how big the grid is. It's almost like grid acts as a floating box influencing water in the front even though it is an open grid and shouldnt do it,.

[cb LLC]

i dont know tried everything grid size, levels etc nothing works still see border. The raft is only 1.5 meters long maybe phoenix can only deal with huge ships not to see the border Hopefully new releases will fix this limitation

[Svetlin.Nikolov]

The thing is that there is no such limitation.

I'd suggest trying to simulate without the vessel just to check if a simple empty simulator still causes this - this will provide some information on what to look at when determining which factors cause this behavior.

Cheers!

[cb LLC]

The thing is that there is no such limitation.

I'd suggest trying to simulate without the vessel just to check if a simple empty simulator still causes this - this will provide some information on what to look at when determining which factors cause this behavior.

Cheers!

Hi Svetlin,
it is still doing it even with just empty grid. The grid is linked to a moving dummy that follows path. I am not sure why. Could you look at the scene maybe I am doing something wrong. Thank you

[Svetlin.Nikolov]

It looks like the issue occurs with a rotating container. Will ping you when we know more...

[cb LLC]

Thank you!

[cb LLC]

It looks like the issue occurs with a rotating container. Will ping you when we know more...

Hi I also have another problem When I click simulate plain water it becomes wavy after 60 frames or so. No forces in the scene Why cannot water be calm? Thanks

[lander]

I used this build 3.11.03 Nightly, Build ID: 2018081128442
And got a similar problem with the grid reacting to movement causing a foam effect from the corner.

[Svetlin.Nikolov]

Hey,

There is a constant tug of war between the gravity and the forces that preserve the liquid volume. With a low scene scale, the gravity is much bigger in relation to these forces and they struggle to keep the liquid from flattening out on the bottom.

This can be resolved by using more steps per frame, or a larger scene scale - in this case your container is only 2 meters wide and you are using only 4 steps, so both contribute to the liquid starting to jitter.

Hope this helps!

[Svetlin.Nikolov]

lander , looks like what you have might be a different problem. A moving container and foam are two additional factors that might be causing this. If your simulator scale is correct in real world, then you could work around this by using a birth volume geometry for the foam, where you can limit it only around the ship.

Cheers!

[cb LLC]

Hey,

There is a constant tug of war between the gravity and the forces that preserve the liquid volume. With a low scene scale, the gravity is much bigger in relation to these forces and they struggle to keep the liquid from flattening out on the bottom.

This can be resolved by using more steps per frame, or a larger scene scale - in this case your container is only 2 meters wide and you are using only 4 steps, so both contribute to the liquid starting to jitter.

Hope this helps!

Thanks. But in real life I can have a cup of water and it will be 100% smooth and flat with a true scene scale of 1. SPF dont help a lot. Can this be ever addressed in future releases? Thanks

[Svetlin.Nikolov]

Hey,

This problem is something we haven't paid much attention because usually with a fluid sim you want it to move and not remain calm and flat. The easiest way we would approach the problem internally would be to add some damping to the velocities, but this is something you can also do from the user side as well to work around it - just add a drag force, or a mapper setting the velocity to zero (a black texmap) and it should freeze the simulator too.

Cheers!

[cb LLC]

Hey,

This problem is something we haven't paid much attention because usually with a fluid sim you want it to move and not remain calm and flat. The easiest way we would approach the problem internally would be to add some damping to the velocities, but this is something you can also do from the user side as well to work around it - just add a drag force, or a mapper setting the velocity to zero (a black texmap) and it should freeze the simulator too.

Cheers!

Thanks. yes it would be nice if you can add some sort of a slider called Still Water for example. That way when set to 0 fluid is frozen and as soon as an object touches it we can animate the slider to 1 and fluid can interact with a it.