Reply To: FSI coupling

[Alex R.]

Hello Mamun,

Here are some feedback points on how I would tackle this problem. My starting position will be having the aluminum part right above the water. 

Create 10 AMMGs: 1 for water, 1 for vacuum or general air, 8 for air, one for each compartment underwater.
It’s important to ensure each compartment is filled with a different AMMG so the coupling can be tracked correctly.

Now, proceed with filling the ALE/S-ALE mesh. First, create eight mesh cubes (dummy parts, can be elastic), one for each underwater compartment, they will be used in the filling operation. Use *INITIAL_VOLUME_FRACTION_GEOMETRY for this. Take advantage of the container filling options: PART (CNTTYP = 1) and Plane (CNTTYP = 3).

Start by filling the entire ALE mesh with vacuum. Then, fill the water using the PLANE specification. Finally, fill each compartment with air by specifying the filling geometry for PART. Refer to *INITIAL_VOLUME_FRACTION_GEOMETRY for more details.

Coupling can be defined using 9 *CONSTRAINED_LAGRANGE_IN_SOLID: Part Lagrange for wate, 8 Part Lagrange for trapped air. Be sure to use MCOUP < 0. This will require wrapping the AMMGs into *SET_MULTI-MATERIAL_GROUP. Each SET_MULTI-MATERIAL_GROUP should contain only one AMMG.

Gradually ramp up the gravity curve from 0 to apply a gentler boundary condition and reduce oscillations in the model.

You may also consider using the S-ALE solver instead of the ALE solver. See *ALE_STRUCTURED_MESH and *ALE_STRUCTURED_MESH_CONTROL_POINTS for further details.

Please let me know how it goes, 
Thank you,
Alex