Entropy source strength

The entropy source strength < > is the rate of entropy production per unit volume... 

The product of the entropy source strength and the absolute temperature is called the dissipation function 4 ... 

When the T is the environmental temperature, the dissipation function represents the energy dissipated to the environment. The entropy source strength and the dissipation function are not state functions, and they depend on the path between the given states. 

Equation (3.116) shows that the rate of change of the entropy per unit volume of substance is due to the convection entropy flow p.w. the conduction entropy flow j v. and the entropy source strength The conduction entropy flow is... 

From Eqs. (3.118), (3.137), and (3.138), the entropy source strength or the rate of local entropy production per unit volume < > is defined by... 

The rate of entropy production is obtained from the local value of entropy production or entropy source strength d>... 

One of the contributions to the modified heat flow is the motion of the Brownian particles. The entropy source strength is due to heat flow and due to diffusion in velocity space (internal degree of freedom), which is the contribution of the motion of the Brownian particles in the heat bath. 

A central quantity of this treatment is the entropy production, a(r, t). The entropy density, in contrast with the previous extensive property densities, is not conserved. To obtain an expression for the entropy production one has to postulate a local version of the Gibbs relation (the second law of thermodynamics) r d5 = dU + pdV. After some manipulations the entropy source strength can be given as ... 

In the above, Ps(r, t) is the entropy density, Osir, t) the entropy source strength, and Jsip, t) the entropy current density. The volmne integrations in Eqs. (293) (294b) are over the spatial domain V occupied by the system. The surface integration in Eq. (295) is over the boundary surface S separating the system from its surroundings. The unit vector h is normal to S and directed outward. 

---