Boundary conditions

Once the geometry of the control domain is defined, we have to proceed with setting the boundary conditions of the problem (access the Conditions menu as shown in previous examples). The conditions to be applied in this example are:

Velocity Field

The Velocity Field condition is used to fix the velocity in a surface to the velocity field given in the Data > Initial Data >RANSOL menu. For this example, this condition is going to be applied to the surfaces of the problem geometry. In our case, all the velocity components have to be fixed (i.e. mark Fix_Initial_X and Fix_Initial_Y). Then, the velocity will be fixed to its initial value and will remain constant during the simulation process.

Fix Concentration

The Fix Concentration condition is used to fix the concentration in a surface to the velocity field given in the Data > Initial Data >ADVECT menu.This condition is going to be applied to the inlet lines of the problem in order to fix the value of the concentration of species at the given value. Note that the value of the concentration of every species should be prescribed at every inlet boundary.

The Value field is the value of the concentration of the species (0.0 in our case).

This condition has to be applied twice to the two inlet lines (joined in the bottom-left corner). Once, with the Species Name field set to Species1 and the second time with the Species Name field set to Species2.

Finally, Figure 113 gives an overview of the conditions and properties assigned.

 

Figure 113. Overview of conditions and properties assignment.

Condition/Material

Entity

Velocity Field surface (Fix_X, Fix_Y)

Surface 1, 2

Pressure Field surface (Fix_X, Fix_Y)

Surface 1, 2

Fix Concentration Line (Species 1)

Line 2, 3

Fix Concentration Line (Species 2)

Line 2, 3

Fluid

Surface 2

Fluid_Source

Surface 1