[Egorqa927]

Hi Dear specialists!

I now simulation free fallin ball in water in 2D. For base I used tutorial in fluent 6DOF+VOF where cube droped in water.

I use next settings:

1. Transient, graviation y=-9.81
2. Multiphase - VOF (With implict body force). K-epsilon turbulence model.
3. Operation conditions: oper press = 101325 Pa, Density = 1.225 kg/m^3.
4. Primary phase - water ( with density and speed of sound how in UDF from tutorial). Secondary phase - air.
5. Dynamic mesh - 6DOF for my ball. Mass in kg, and moments inertions in X,Y,Z = (2*m*R^2) / 5
6. Scheme: SIMPLE; Press-PRESTO!; Moment,Density-Second order; VOF-Geo-reconstruction; Turbulence-First Order.
7. Deafuls under-relax factors.

My problems:


1. Results experimental and calculations by fluent - difference! WHY?
2. I not can use time step more then 0.0001 sec when ball in water, because I have wrong pressure. Only with timestep = 0.0001 sec I have good resudial and pressure. WHY?

I hope here will be a person who can help me with my problem.

Big thanks for your time.

[samir_cfd]

Hi Egor
I am simulating the same case in Fluent but I have a problem, when the ball is close to the free surface the solution diverege (divergence problem) I don't know where is the problem exactly and how to solve it?
Many thanks!!

[Pichen]

Originally Posted by samir_cfd

Hi Egor
I am simulating the same case in Fluent but I have a problem, when the ball is close to the free surface the solution diverege (divergence problem) I don't know where is the problem exactly and how to solve it?
Many thanks!!

Hi samir_cfd
I am simulating a rod drop.
If the mesh is Tet with inflation. When the rod drop, it appears negative
If the mesh is Tet without inflation.That is ok using the same setting.
Is there some method to make the inflation move with the rod ?