Boundary conditions

Once we have defined the geometry, it is necessary to set the boundary conditions of the problem. This process is carried out through the RANSOL conditions window (see Figure 10). The only conditions to specify here are:

a)      Fix velocity [line]

b)      Fix pressure [point]

 

Figure 10 Open condition assignment window and icon

Remarks:

If the RANSOL conditions window is not available, please check that the RANSOL module is active in the Tdyn Preferences window (see Figure 3).

a)      Fix velocity [line]

This condition is used to impose the velocity on a line. The available fields stores the velocity components (X and Y) given in global axes and the flags Fix_X and Fix_Y allows to indicate if the corresponding components have to be fixed or not. If the Fix flag is not selected, the corresponding field will be disabled. For this example this condition is going to be assigned to the line swept by the flow. In our case, the X-component of the velocity vector will be set to 1.0 m/s, and the Y-component to zero. Then, all the velocity components have to be fixed to the specified value (i.e. mark Fix_X and Fix_Y, see Figure 11).

  

Figure 11 Fix Velocity [Line] condition window

b)      Fix Pressure [Point]

In most cases, it is recommended to fix the pressure at least in one point of the control domain (taken as reference). If this condition is not applied, Tdyn makes necessary corrections and the solution of the problem is equally achieved. In this case, it will be applied to the bottom left corner, as shown in Figure 12.

  

Figure 12 Fix Pressure [Point] condition window