Page 346 - TransAT_Tutorial_Manual

TransAT Tutorial Manual 8.1. Flow around a train entering a tunnel

A block modification will be used to create the tunnel section on the right side of the domain:

• Using the Select Blocks select block 2 and then click the button.
• Enter 0.02m in the Y max field

• Click

BCs Tab
The boundary conditions will now be set. Pressure outflows will be used where an open surface
is to be considered, and Wall will be used to model the tunnel walls. Other surfaces will be set
as Symmetry boundaries.

• Ensure the Outlow BC is available, and make sure its type is Outlow. Click to define its
parameters. In the General tab, define the following properties:

– Outflow Type: Pressure
– Outflow Data Source: From Boundary Conditions
– Outflow Pressure: 0
– Pressure Loss Coefficient: 0

In the backflow properties tab define the following properties:

– Backflow turbulence intensity: 0.1
– Backflow eddy viscosity ratio: 10
– Click to save the settings and close the window.

• Confirm that the Wall BC has a type of Wall.

• Select the XMIN 0 surface in the surface list.

• Check the Outflow boundary condition in the list of boundary conditions by clicking the
light grey square at the corresponding line. Then, click to apply the boundary condition
to the XMIN 0 surface.
• repeat the operation to assign the following boundary conditions as suggested below:

– Assign XMAX 0 to Outflow
– Assign XMAX 1 to Wall
– Assign YMIN 0 to Symmetry

– Assign YMAX 0 to Outflow

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Ascomp AG Switzerland 336 Version 5.7