Passage of a thermodynamic system from an initial to a final state of thermodynamic equilibrium.

Below is the list of popular ideal Thermodynamic processes:

T(t) = {\rm const} \Leftrightarrow \frac{\partial T}{\partial t} = 0

Isobaric process

P(t) = {\rm const} \Leftrightarrow \frac{\partial P}{\partial t} = 0

Isochoric process

V(t) = {\rm const} \Leftrightarrow \frac{\partial V}{\partial t} = 0

Isentropic process

S(t) = {\rm const} \Leftrightarrow \frac{\partial S}{\partial t} = 0

Adiabatic process

\frac{\partial (Q^{\downarrow}-Q^{\uparrow})}{\partial t} = 0

All the above processes are idealized and the practical studies and engineering are dealing with approximations to these processes, like for example, Quasi-isothermal process.

See also