Niki Papachristou
Ansys Employee

Hi Shafayeth,

Thank you for reaching out to us, from your graphs I believe that you might have formed a cavity somewhere in your simulation region. Thw most common case has to do to with the boundary conditions. What boundaries are you using? How close are they to your structure? Typically, half the max wavelength is enough, but this is to be confirmed with some convergence testing.