Modeling dual-chamber air spring with orifice damper

enoeno

I am trying to model an air spring consistes of two large air chambers about 20' by 20' by 35'each connected by an oriface of diameter to be decided.
The gas is air with intial pressure of 1 ~ 2 atm.
One chamber volume is altered by a piston like mechanim providing an excursion of +-20 ft at frequency of 15 seconds.
I am thinking of modeling the oriface as a a damper in parallel with one of the spring and then in series with the second spring like the following:

***spring1********spring2******MASS of piston
** -------------*
***dash pod**

Given the conditions, what is the proper way to model the parameters? is adiabetic formula for each chamber ok? How to derive the damper coefficient of the oriface? Or some more realistic model is needed?