FTP, name this quantity equal to internal energy minus the product of temperature and entropy, a state function named for a German physicist.
The Cushman group at Purdue has shown that changes in this value determine drive flow in swelling systems not pressure gradients and external fields.  Represented by a capital A, change in it can be defined as the work, in a reversible process, under constant volume and constant temperature.  FTP, name this quantity equal to internal energy minus the product of temperature and entropy, a state function named for a German physicist.
The Cushman group at Purdue has shown that changes in this value determine drive flow in swelling systems not pressure gradients and external fields.  
Helmholz free energy