Encyclopaedia Index

WORKSHOP - LVEL Turbulence Model

This workshop shows how the LVEL model can be applied to a case with several blockages, in order to calculate the distance from each cell to the nearest wall. It is based on Library Case 293.

Accessing PHOENICS-VR.

From the system level:

To enter the PHOENICS-VR environment, click on the PHOENICS icon on the desktop, or click on Start, programs, PHOENICS, PHOENICS.

This is the default mode of operation.

From the commander level:

To enter the PHOENICS-VR environment, click on the 'Run vre' icon in the left column.

Within VR-Editor,

Start with case 293 - click on 'File' then on 'Load from libraries'. Enter 293 in the Case number box, then click on 'OK'; to load the case.

Click on 'SATELLITE command prompt' and press 'return' key until the geometry appears on the screen. You may now close the command prompt.

Reset the material of the blockages

The three blockages are made of material 199 - this allows fluid slip. It provides no boundary conditions for the wall-distance calculations.

Click on each blockage in turn, to bring up its Object specification dialog box. Click on Attributes, and change the material to 198 - Solid with smooth-wall friction.

Activate the LVEL model

Click on Main Menu, then on Models.

Click on 'Turbulence models' button. From the list of turbulence models, select LVEL.

Use 'Automatic convergence technique'

Click on 'Numerics' and then 'Relaxation control'

Toggle 'Automatic convergence control' from Off to ON.

Click on 'Reset solution defaults'

Click 'Previous panel', 'Top menu' and 'OK' to quit the main menu.

Running the Solver.

In the PHOENICS-VR environment, click on 'Run', 'Solver', and click on 'OK' to confirm running Earth.

Using the VR Viewer.

In the PHOENICS-VR environment, click on 'Run', 'Post processor',then GUI Post processor (VR Viewer) Viewer)'. Click 'OK' on the file names dialog to accept the default files.

To view:

• Vectors - click on the 'Vector toggle'
• Contours - click on the 'Contour toggle'
• Streamlines - click on the 'Create Streamline' button
• Iso-surfaces - click on the 'Iso-Surface toggle'

To select the plotting variable:

• To select Pressure - click on the 'Select Pressure button' .
• To select Velocity - click on the 'Select Velocity button'
• To select Temperature - click on the 'Select Temperature button'
• To select any other variable - click on the 'Select a Variable button' . Select DEN1 for density, or ENUL for laminar viscosity values.

To change the direction of the plotting plane, set the slice direction to X, Y or Z

To change the position of the plotting plane, move the probe using the probe position buttons

.

The plot below shows contours of the wall distance variable WDIS.

Saving the results.

In the PHOENICS-VR environment, click on 'Save as a case', make a new folder called 'LVEL' (e.g.) and save as 'CASE1' (e.g.).