Problem of fluid particles splash during simulation

dong

Hi guys:
I was recently troubled with a problem of particles splashing during simulation. There are some floatings moving in the water and generate waves , the phenomenon in the previous section is correct ,but some particles will splash and into the air, such as follows:


Is this problem relative to any parameters?

Asalih3d

Hi Dong

Could you please describe more in detail what we are looking at? It can be hard to provide any useful insight without understanding your situation enough.

I will note that I have beforehand experienced "splashing" and in my case it was realistic since the water got disconnected from the main volume and starting mixing with air.

dong

@Asalih3d

In this simulation a stream of water flows on the floatings, and some fluid particles fly away. Is this realistic?

Alex

Try to use a higher viscosity value
OR
Try to use double precision

dong

@Alex
Now I have used double precision and I use laminar+SPS , the value is 1e-6，just like water.

Alex

Try to use artificial viscosity so that you can control better those instabilities.
Laminar viscosity is a good example of programming a ACTUAL and PHYSICAL viscosity, however most of the times is not numerically stable, so I suggest to move to artificial viscosity.
Other viscosity treatments such as k-eps should work in a better way than the laminar formulation we have implemented

Regards

dong

@Alex
If I use artificial viscosity and set the value 0.01 or 0.001. When I compute the force with ComputeForces4_linux64 if I can get the right result?

Alex

Artificial viscosity will affect the velocity propagation of the dam (of volume of fluid) so that impact time should vary, however the force magnitude should be corrected.

Note that the force = pressure terms + viscous forces, and generally pressure terms are much higher (at least that seems in your problem)

Regards

dong

@Alex
But how to correct the force if I use artifical viscosity? Is there any reference or principle I can use?

Alex

You do not need to correct the force. Force will be computed using that value of viscosity.
Please try it and tell us if it works or not and we can help you again.

dong

Thanks all
I have solved the problem by changing the RigidAlgrithm. I use the dem so I must set RigidAlgrithm=2(DEM).