Reply To: Fluid-structure interaction coupling

[Ian Do]

Hello Mamun,

Coupling is too involved to explain via this medium! I suggest you try to review my ALE class in ALH (ANSYS Learning Hub). It's difficult, but I'll give it a shot here:

Q1. water and tank - I am using LAGRANGE_IN_SOLID with PFAC=0.001. Is it appropriate?

A1: Always start with the default - this works for many cases - only change its value (PFAC) by 10-30% at a time, only change 1 value at a time.  

Q2. water and the float - same as above

A2: ?

Q3. water and entrained air - EULER_IN_EULER

A3: No need - Think of the ALE computational domain or mesh as containing 2 mats. If 1 mat moves into an elm, the other has to be pushed out. This is automatic. 

Q4. floating object and entrained air - This is needed to gravity initialize the system as the weight of the floating body will compress the entrained air. Also, there will be a vertical seismic excitation on the system which will cause interactions among various components. I am not sure what types of interaction I should use. I would greatly appreciate any suggestions.

A4: I would suggest you learn S-ALE approach, newer, better, simpler approach, but this is complex and cannot be taught in this forum. It will require a class! 

Since your questions are set in the traditional ALE approach, I will answer the way you ask.

• define LAG part, H1, say, (& it's better to make it deformable, ex; MAT_ELASTIC ...)
• define the total ALE domain/mesh = H2 = background mesh = outside air MMG3
• use volume filling KW to fill in the water space (MMG1, using a simple box) and the trapped air (MMG2, using the segment-set of the internal surface of the cavity, call this segment-set1)
• define coupling card 1: MCOUP==> MMG1 is coupled to H1 (CONSTRAINED_LAGRANGE_IN_SOLID ...)
• define coupling card 2: MCOUP==> MMG2 is coupled to the segment-set1

I hope this helps.

Ian Do