https://www.comsol.fr/model/tunable-evanescent-mode-cavity-filter-using-a-piezo-actuator-12619
Tunable Evanescent Mode Cavity Filter Using a Piezo Actuator
Use this model or demo application file (and its accompanying instructions) as a starting point for your own simulation work.
evanescent modepiezo actuatortunablecavityfilter