Learning Forum

[csZY]

Hello, sir.

I am now using a dynamic mesh to simulate the settlement of objects (only affected by gravity and fluid viscosity), using a 6DoF model. I use UDF. Do I need to add buoyancy to the 6DoF UDF? Or just check the gravity in general?

My object only moves in the z-direction, and is initially subject to no other forces except gravity and the force exerted on it by the fluid. Will the 6DoF model automatically calculate buoyancy and other forces?

Thanks

[Rob]

It'll get worked out using the 6DOF mass relative to the surrounding fluids, and gravity. I'm not sure of the exact mechanics but check the examples in Help as we usually demonstrate the function with a lifeboat launch or things falling off aeroplanes. 

[farzad pour]

[farzad pour]

Could you solve the problem? 

[Rob]

What problem? 

[farzad pour]

I mean "csZY".
 want to simulate free falling of a disk in the Fluent, but I can't. My literature review shows that free falling of a fully submerged body hasn't done by ANSYS-FLUENT but  some papers have done it by STAR-CCM+!

I hope, finally I will do by FLUENT! 

[Rob]

We've been doing it in Fluent since v6.x so about 21 years: look in the Fluent Help examples. 

[farzad pour]

@Rob

Despite searching a lot, I couldn't find any documents related to particles/bodies that are fully submerged in water or other fluids with high viscosity and density.

Could you please introduce any documents that are related to simulation of free falling of a fully submerged body in the water? 

Best regards.

[Rob]

Click on Help in Fluent, and there's a lifeboat launch video. Similarly Tutorial 14 covers 6DOF. Remember that buoyancy is merely the result of the object and surround fluid density being different - so a drop tank falling though air is negatively buoyant, but may well float (buoyant) in water and is modelled in the same way in both cases.