Page 166 - Process Modelling and Simulation With Finite Element Methods

Extended Multiphysics 153
,

water di ersion 1

let
L

Figure 4.10 Schematic of a stratified buffer tank with potentially two types of inlets and one outlet.

In this subsection, we develop a two-component mass and momentum
transport model for dense solute in a 2-D buffer tank. It is set up so that it can be
augmented with a 1-D heterogeneous reactor with recycle model from the
previous section. No lumped parameters are ever used in this model, as the
detailed distributed effects of convection on mass transfer by coupling with
diffusion and back action of density variations on convection are computed
directly.
We will build up the model piecemeal, starting with the Incompressible
Navier-Stokes model, then successively adding one mass transport mode, solutal
Rayleigh effects, and then a second mass transport mode.
Component 1: Navier-Stokes flow field for cavity flow driven by free stream

Enter the Model Navigator.

Model Navigator _I_
Select 2-D dimension
Select the Incompressible Navier-Stokes, time-dependent

Pull down the Options menu and set the grid to (0,5) x (0,5) and the grid
spacing to 0.5,0.5. Pull down the Draw menu and select RectangleBquare
(R1)and place it with vertices [O,O] and [0,5]. Now draw R2 with vertices [1,5]
and [5,5].
Pull down the Boundary menu and select boundary settings

Boundary Mode
Set up boundary 1 u=O; v=O, inflow
Set up bnd 2,3,5,7 no slip
Set up bnd 6 outflow p=O
Apply/OK