Issues with modifying official LS-DYNA ex with S-ALE mesh

[HL]

Hello, I would greatly appreciate some help regarding my code. I am taking an official LS-DYNA example, Underwater F (https://lsdyna.ansys.com/underwater-f/), and modifying it to create an S-ALE mesh without the cutout.

I am generating a square field. I fill the entire region with water and there is a smaller square region in the bottom left corner, in which I place an explosive material. I detonate the bottom left corner, the origin, at time 0.

However, the detonation front created by this explosion is not propagating smoothly into the water. It looks like there is a boundary at the box region, even though I have not defined a boundary. Might this be due to a discontinuity in the interface between the two materials or is there something I am missing in my code? How would I fix this? Thank you very much in advance.

Here is the input file:

*KEYWORD

*NODE

       1 0.000000000E+00 0.000000000E+00 0.000000000E+00

       2 0.000000000E+00 0.000000000E+00 0.000000000E+00

       3 0.100000000E+00 0.000000000E+00 0.000000000E+00

       4 0.000000000E+00 0.100000000E+00 0.000000000E+00

*ALE_STRUCTURED_MESH_CONTROL_POINTS

      1001

                   1       0.0

                  51       8.0

                 201      32.0

*ALE_STRUCTURED_MESH_CONTROL_POINTS

      1002

                   1       0.0

                  51       8.0

                 201      32.0

*ALE_STRUCTURED_MESH_CONTROL_POINTS

      1003

                   1       0.0

                   2       1.0

*DEFINE_COORDINATE_NODES

       234         2         3         4

*ALE_STRUCTURED_MESH

         7      5000     10000     10000

      1001      1002      1003         1       234     

*DEFINE_BOX

         9       0.0       8.0       0.0       8.0       0.0       1.0

*PART

 

         1         1         1         1

*PART

 

         2         2         2         2

*MAT_NULL

         1       1.0

*MAT_HIGH_EXPLOSIVE_BURN

         2      1.63     0.784     0.260 0.000E+00

*EOS_GRUNEISEN

         1       1.5

 

*EOS_JWL

         2      3.71 3.230E-02      4.15     0.950     0.300 4.300E-02      1.00

*ALE_STRUCTURED_MULTI-MATERIAL_GROUP

     water         1         1

      expl         2         2

*ALE_STRUCTURED_MESH_VOLUME_FILLING

         7               water

       ALL

*ALE_STRUCTURED_MESH_VOLUME_FILLING

         7                expl

    BOXCOR         0         9

*CONTROL_ALE

         0         1         2      -1.0

 

*CONTROL_ENERGY

         2         1         2         2

*INITIAL_DETONATION

      5000 0.000E+00 0.000E+00 0.000E+00 0.000E+00

*CONTROL_TERMINATION

     100.0

*DATABASE_BINARY_D3PLOT

       1.0

*DATABASE_GLSTAT

       0.1

*END

 

Here are screenshots of the relevant time steps: