Try with the eos parameter I gave you. You'll can try the murnaghan to speed up your run once the results with the eos_polynomial are satisfying. Also, try to refine the mesh to see if there is convergence between meshes.
Also, don't forget SPH and ALE are two different methods. When you use SPH, you use a *CONTACT_AUTOMATIC_NODES_TO_SURFACE between fluid and structure and it's totally different than the coupling in ALE with a *CONSTRAINED_LAGRANGE_IN_SOLID or *ALE_STRUCTURED_FSI so you will expect variation.
Best Regards,
Loïc
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