The Impervious Mass Layer condition adds a mixed condition for the porous matrix as well as the saturating fluid. A distributed mass is applied on the boundary resulting an effective (frequency and displacement dependent) load for the elastic matrix, while an impervious (sound hard) condition is applied to the saturating fluid movement.

Select the Mass type as Mass per unit area or Total mass, then enter the desired mass density ρA or total mass m. For both select if the mass distribution is Isotropic, Diagonal, or Symmetric.