You said your objective is
to find the harmonic response of perforated plate, ie how much sound is absorbed if the sound is passed through it, (to get a graph between the absorption coefficient and frequency.)
and your approach to obtaining this information is to build a model in ANSYS using simulation methods you don't sufficiently understand. That doesn't seem like the most straightforward approach.
If that was my objective, I would go into the lab and do a measurement on a physical sample using an actual impedance tube, a pair of microphones and a data acquisition system. I am fortunate to have the microphones and data acquisition system, and I could have an impedance tube made or purchase or rent one.
My objective is to learn how to build acoustic models in ANSYS. Maybe that is your objective too, since you are posting on the ANSYS Student Community site and not a sound measurement site.
When I am learning simulation software, I like to find textbook problems where I know the answer, and see if I can build a model to give the same answer. I have been doing this in acoustics and was able to predict the natural frequencies of columns of air that match equations in books. That is a good way to build confidence in my ability to model new physics. I recommend you take a similar approach .
It seems you are just adding things to your model to "improve the fit" without understanding what those things do. Why does your model have a Mass Source AND an Incident Wave at port 1? These are both adding waves at the speaker end of the tube. For the Incident Wave, why for the Wave Type did you choose Circular Duct and not Plane Wave? An impedance tube is intended to have a plane wave. Why did you add a Monopole Acoustic Wave Source at the center of your impedance tube, which generates spherical waves and not plane waves. There is an expression called Garbage in, garbage out. What does it matter if the output from the model looks something like what you saw in a paper if the model does not simulate the fundamental physics of the problem? The model will have no value.
I have some more notes in the attached zip file of a Word document.