Nonconvective flow

Diffusional transport is the nonconvective flow that tends to equilibrate the concentrations in inhomogeneous non-equilibrium systems. From Eqns. (4.43) and (4.45), we have... 

By virtue of their definitions, the nonconvective flows J must obey the relation... 

The nonconvective energy flux across the boundary is composed of two terms a heat flux and a work term. The work term in turn is composed of two terms useful work deflvered outside the fluid, and work done by the fluid inside the control volume B on fluid outside the control volume B, the so-called flow work. The latter may be evaluated by imagining a differential surface moving with the fluid which at time 2ero coincides with a differential element of the surface, S. During the time dt the differential surface sweeps out a volume V cosdSdt and does work on the fluid outside at a rate of PV cos dS. The total flow work done on the fluid outside B by the fluid inside B is... 

The actual solution algorithm is often based on the arbitrary Lagrangian-Eulerian (ALE) method of Hirt et al. [22]. In this method, in order to make the solution computationally more efficient, a decoupling of the convective and nonconvective gas-phase terms in each time step is introduced. In the Lagrangian phase, where the computational cells move with the fluid flow, the spray PDE is updated and the source terms due to liquid and chemistry are evaluated. Also, the nonconvective... 

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