## Fluids

#### motion of a solid cylidrical object inside a pipe , filled with water

• aryamnsaini
Subscriber

I am doing a problem in which the motion of a solid cylinder with spherical end has to be analysed. the cylinder is moving with supersonic speed and the clearance with pipe wall is very low.

what can be the approach to solve this kind of problem?

• DrAmine
Ansys Employee

Overset + prescribed CG motion might be a solution.

• salmanouh4269197moa
Subscriber

Hello,

I'm also simulating  a rotating drum filled with spherical particles and I'm confused about how to simulate the motion of the drum with the particles inside

is it correct to enable the Moving Wall under the boundary condition or go for the dynamic mesh ?

am using Eulerian Granular multiphase model - transient flow  for 2D domain.

• Rob
Ansys Employee

If it's just rotating moving reference frame or sliding mesh will do it: dynamic/overset mesh is only really needed if the relative positions of bits of geometry or shapes change.

• DrAmine
Ansys Employee

To be safe always use mesh motion and rotate the whole drum.

• salmanouh4269197moa
Subscriber
Thanks, I have tried the single moving reference frame and it's seems it will work but the conversion is not complete due to floating point l do not know why?
Would You help!
• DrAmine
Ansys Employee
Paste here all relevant details of your case
• salmanouh4269197moa
Subscriber

Yes, Its Here

• Rob
Ansys Employee

Try dropping the Courant Number to about 10-20 (200 is only viable for airfoil type models)  but it's likely you'll need the transient solver: multiphase models are nearly always transient.

• DrAmine
Ansys Employee

I guess you only want to run particle simulations right? If YES: I have done that last week: switch off all flow equations and run just DEM particle with a suitable particle time step size/flow time step size which is 1/20 of particle collision.

• salmanouh4269197moa
Subscriber

Yes I'm doing Particles simulation and it should be in 3D

Do you mean Discrete Element Model? If yes. How I can I applied using Fluent?

Regards

• salmanouh4269197moa
Subscriber

So for the Courant Number, I need to key-in the value not Fluent will calculated based on the

element size ,inlet velocity and  the time step?

Regards,

• manav2107
Subscriber

I am working on the similar problem. In which a robotic tool is to move (with some velocity) inside a pipe due to differential pressure (upto 150 bar) generated. The pressure must not bye-pass the tool, otherwise it wouldn't move. Also, it should vary its size with the variation of pipe, I am stuck with this problem. What should I do?

• Rob
Ansys Employee

If there's no flow leakage then the motion is purely pressure & friction based. You might be better using Mechanical for the contact models.

• manav2107
Subscriber

but the problem is that it has to move always in compression inside the pipeline like a pigging tool. will it be possible in Mechanical?