Encyclopaedia Index

WORKSHOP - Fine Grid Embedding.

This workshop shows how to use a Fine Grid Volume to increase the local resolution. The case considered is the flow over a cylinder.

fge1.gif (11967 bytes)

Within PHOENICS Environment:

Start with an 'empty' case - click on 'File' then on 'Start New Case', then on 'Core', then click on 'OK'; to confirm the resetting.

Within VR Editor:

Set domain size and activate solution of variables

Click on 'Main Menu'.

Set the title to 'Flow over a cylinder (FGEB)'

Click on 'Geometry'.

Set the Domain size to 8.0 m in X, 6.0 m in Y and 1.0 m in Z

Click 'OK' to close the Grid mesh settings dialog.

Click on the 'Reset' button on the movement control panel

Click on 'Fit to window' and 'OK'

Click on the 'Mouse' button and use mouse to rotate the view in X-Y plane.

Click on 'Models'.

Solution for velocities and pressure: ON

Turbulence models: Laminar

Click on 'Top menu'.

Click on OK.

Create blockage for CYLINDER

Click on 'Settings', 'New'and 'New Object';.

Name: Cyln

Click on 'Size' and enter:

Xsize: 0.6

Ysize: 0.6

Zsize: 1.0

Click on 'Place' and enter:

Xpos: 3.7

Ypos: 2.7

Zpos: 0.0

Click on 'General' and enter:

Type: BLOCKAGE

Click on 'Shape' and select the geometry: PUBLIC/SHAPES/cylinder

Click 'Options' and de-select 'Object affects grid'

Click on OK.

Create Fluid Inlet

Click on 'Settings', 'New' and 'New Object'.

Name: inlet

Click on 'Size' and enter:

Xsize: 0.0

Ysize: 6.0

Zsize: 1.0

Click on 'General'

Type: INLET

Click on 'Attributes'.

Set a velocity of 1.0 m/s in the x-direction.

Click on OK/OK.

Create fluid Outlet

Click on 'Settings', 'New' and 'New Object'.

Name: outlet

Click on 'Size' and enter:

Xsize: 0.0

Ysize: 6.0

Zsize: 1.0

Click on 'Place' and enter:

Xpos: 8.0

Ypos: 0.0

Zpos: 0.0

Click on 'General'

Type: OUTLET

Click on OK.

Create a Wall at the low side of the domain

Click on 'Settings', 'New', 'New Object'.

Name: Lwall

Click on 'Size' and enter:

Xsize: 8.0

Ysize: 0.0

Zsize: 1.0

Click on 'General'

Type: PLATE

Click on OK.

Create a Wall at the High side of the domain

Click on 'Settings', 'New', 'New Object'.

Name: Hwall

Click on 'Size' and enter:

Xsize: 8.0

Ysize: 0.0

Zsize: 1.0

Click on 'Place' and enter:

Xpos: 0.0

Ypos: 6.0

Zpos: 0.0

Click on 'General'

Type: PLATE

Click on OK.

Create the first Fine-grid volume

Click on 'Settings', 'New' and 'New Object'.

Name: fine1

Click on 'Size' and enter:

Xsize: 4.0

Ysize: 2.0

Zsize: 1.0

Click on 'Place' and enter:

Xpos: 2.0

Ypos: 2.0

Zpos: 0.0

Click on 'General'.

Type: FINE_GRID_VOL

Click on 'Attributes'.

Fineness X: 2

Fineness Y: 2

Fineness Z: 1

This will double the grid within the fine-grid object. You may click on the 'mesh toggle' button on the main controll panel to view the grid

Click on OK/OK.

Create the second Fine-grid volume

Click on 'Settings', 'New' and 'New Object'.

Name: fine2

Click on 'Size' and enter:

Xsize: 2.0

Ysize: 1.0

Zsize: 1.0

Click on 'Place' and enter:

Xpos: 3.0

Ypos: 2.5

Zpos: 0.0

Click on 'General'.

Type: FINE_GRID_VOL

Click on 'Attributes'.

Fineness X: 2

Fineness Y: 2

Fineness Z: 1

This will double again the grid within the fine-grid object. You may click on the 'mesh toggle' button on the main controll panel to view the grid

Click on OK/OK.

Setting the Probe Location

Click on the probe icon on the toolbar or double-click the probe itself, and move the probe to X=7.0, Y=3.0, Z=0.5.

Set remaining solution control parameters

Click on 'Main menu'.

Click on 'Numerics'.

Total number of iterations: 250

Click on 'Top menu'.

Click on OK.

Running the Solver.

In the PHOENICS-VR environment, click on 'Run', 'Solver' (Earth), 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) . Click 'OK' on the file names dialog to accept the default files.

To view:

To select the plotting variable:

To change the direction of the plotting plane, set the slice direction to X, Y or Z slice direction (927 bytes)

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

probe position (927 bytes).

A typical plot from this case is:

velocity vectors

Saving the results.

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