Learning Forum

[yipxx043]

Hi Forum,

I can't seem to find a lot of information about the multi-material ALE interface reconstruction process in the manual and want to understand how my simulations are handling the interfaces between 2-3 materials. I found some materials online from Dr. Hao Chen, but I'm not if it is just generating a new cut plane at each time step given updated volume fractions within a given cell or is it actually tracking the surface akin to a level-set method? 

Peter

[Neetu Jha]

In LS-DYNA’s multi-material ALE, the interface reconstruction is typically done using a per-timestep volume-fraction approach, specifically through the piecewise linear interface construction (PLIC) method. This method involves generating a new cut plane within each cell based on the updated volume fractions. The PLIC method is employed to construct the interface front by determining the size of the cut in the cell where the interface likely passes through, and the direction of the interface is determined by the gradient of the level-set function. This approach is documented in the LS-DYNA Keyword and Theory Manuals. 

Additionally, the LS-DYNA manual discusses the use of volume fractions in the initialization of multi-material cells, which is part of the interface reconstruction process. 

The manual also provides information on the ALE workflow, which includes forming an isosurface on the volume fraction of each material in a cell, typically at 50%, to find the exterior surface of each material in its current location in the S-ALE domain. 

5.2. ALE Workflow

[yipxx043]

Hi Neetu,

Thank you for the clarification. This makes a lot of of sense.

Peter