Encyclopaedia Index

Starting with PHOENICS-VR

CHAM Technical Report TR/324

PHOENICS 2012

Document last revised: 31/05/2012

Contents

Short-cut to figures

1 The purpose of this Document

2 The PHOENICS-VR Environment

3 Setting up flow problems

4 The second example - Adding heat-transfer to the previous example

5 The third example - Changing the computational grid in VR.

6 Further information


1 The purpose of this document

The intended reader.

This document is intended for readers who, having just acquired PHOENICS, wish to perform some simple fluid-flow calculations, before learning knowledge about PHOENICS as a whole.

The information to be conveyed.

The activation and use of the following will be described:

This will be done by way of simple examples, illustrated by Fig.1.


Figure 1: The geometry of the VR flow-simulation example

The remainder of the document is divided as follows:

After the start has been made

All this is only a small fraction of what, in the course of time, the PHOENICS users will find it useful to learn.

Thus, the VR Editor is just a simple way of writing the input data file in the powerful PHOENICS input language, PIL. This is the so-called Q1 file. Experienced users often prefer to write those files themselves.

Again, the VR Viewer presents only one way of displaying the results graphically; PHOENICS possesses other graphical display means, for example PHOTON and third party packages such as TECPLOT and PARAVIEW. Many users need to understand and control the numerical output contained in the RESULT file.

Finally, the VR Editor, and its associated menu, can activate only a subset of the PHOENICS flow-modeling capabilities. Many more can be activated by way of:

How to learn about these is explained in TR001, the PHOENICS overview.


2 The PHOENICS-VR Environment

Varieties of Appearance and Means of Activation

The Environment module appears somewhat different according to whether the operating system is:

For Windows, the Environment module can be activated by:

For UNIX/LINUX, the Environment can be activated by entering the command pc in a working window, followed by pressing the RETURN key.

From here onward, discussion will be confined to the Windows situation. For the others, the appearances on the screen will be, though different, sufficiently similar for the current document to be informative.

The Environment screen.

Fig.2 shows what appears when the Environment is activated for the first time.


Figure 2: The PHOENICS-VR Environment screen

On subsequent activations, the screen will show the model that was being worked on previously.

That 'PHOENICS VR-Editor' appears on the top line is an indication that, for Windows/Intel-Fortran PHOENICS, there is little distinction between the Environment and the Editor.

Preparing to Run the First Example

Start the VR-Editor as described above. The VR screen shown in Fig. 2 should appear. To ensure that you start with an empty input file, click on the 'File' button, with the result illustrated by Fig.2a.


Figure 2a: The PHOENICS-VR environment File Menu

Select 'Start New Case', followed by 'Core' and 'OK'. The screen should now look as in Figure 2 above.


3 Setting up flow problems

The VR-Editor

The Editor is used for:

What appears on the screen in a VR-Editor session can be determined (in part) by means of the hand set shown in Fig. 3a, a description now follows.

The VR Editor Control Panel.

The control features of the VR Editor hand set are now briefly discussed. The hand-set is divided into two separate parts - the movement controls and the domain and object controls.

Movement Controls

Four pairs of arrow buttons allow the user to rotate and translate the model domain contained in the graphics window and to zoom the graphics screen in and out.

There are other viewing controls located in the top two rows of the Object and Domain handset, which allow the user to change various other viewing options, such as hiding objects or controlling the view of the current mesh, etc.

All of the viewing controls are summarised in figure 3a. Some viewing controls have two functions, depending on which mouse-button is used to pick them. In the figure, the function activated by the left mouse button is listed before the slash, and the function activated by the right mouse button is listed after the slash.


Figure 3a: Movement controls of the VR Editor Hand Set.

When the Mouse Control button is pressed (it is active by default), the mouse can be used to dynamically rotate the screen image. The mouse functions are listed in the table below:

Mouse button held down Mouse movement Effect Equivalent key
Left Left View left left-click on
Right View right left-click on
Up View up left-click on
Down View down left-click on
Right Left Tilt right left-click on
Right Tilt left left-click on
Up Zoom out left-click on
Down Zoom in left-click on
Middle (or both) Left Move left right-click on
Right Move right right-click on
Up Move down right-click on
Down Move up right-click on
Shift+Left Left Rotate image right about viewer None
Right Rotate image left about viewer None
Up Rotate image down about viewer None
Down Rotate image up about viewer None
Shift+right Left None None
Right None None
Up Move back right-click on
Down Move forward right-click on

If the movement control panel is closed, the mouse is automatically activated.

To quickly zoom in on a portion of the screen, hold the Ctrl key down and move the mouse sideways with the left button held down. A red box will follow the motion of the cursor. When the mouse button is released, the image with the red box will be drawn full-screen. This operation can be undone by pressing Ctrl+z,or backspace.

Main Controls

The control buttons located in the larger handset are referred to as the Main Controls. These are summarised in Figure 3b. Two of the most important controls located in this panel are the 'Main Menu' and 'Object' buttons.

The other control buttons located below the Object button can be used to delete objects, duplicate objects and create arrays of objects, as shown in Figure 3b. All of these main controls will be used in the flow simulation in next section.


Figure 3b: Main controls of the VR Editor hand set.

Users are encouraged to investigate the functions of the various buttons that have been described this far for themselves, before attempting the following flow simulation.

If desired, both control panels can be closed to allow an unobstructed view of the maximised graphics screen. The icons appearing on the control panels can be displayed on the tool bar by clicking on 'View ' - 'Toolbars' - 'All'.

Entering data in the VR Editor.

The quantities to be solved for are pressure and velocity. It will be necessary to specify a flow inlet, and a flow outlet. In addition, two objects referred to as 'fence' and 'cylinder' will be used as blockages.

a. Use the PHOENICS-VR environment screen to create a new file as described above.

To make the required global settings to describe the flow domain fully:

click on the 'Main Menu' button (or on the toolbar). The top page of the Main menu, as shown in Figure 4, will appear on the screen. The menu date may differ from that shown.


Figure 4: The Main Menu top page.

To set the title for this simulation, click on the 'Title' dialog box. Then type in a suitable title, for example 'My first flow simulation'.

To set the size of the Flow Domain, click on 'Geometry' and change the Domain Size in the Z-direction to 0.5 m, see figure 5.


Figure 5: The 'Geometry' page of the Main Menu.

Automatic meshing is switched on by default, this is indicated by the buttons 'X-Auto', 'Y-Auto' and 'Z-Auto' in figure 5 above. Each direction may be toggled to 'Manual' by clicking on these buttons.

The Auto setting will usually generate a grid that is adequate for the first calculations, but may require refinement for the final 'production' calculations. Refining the mesh will be covered in Example 3. Click 'OK' to close the Grid Mesh Settings dialog.

To select which physical processes will be simulated, click on 'Models' to obtain the menu page shown in figure 6.


Figure 6: The 'Models' page of the Main Menu
.

Check the 'Solution for velocities and pressure' button, ensuring that it is set 'ON'.

To set the turbulence model:

Click on the 'Turbulence models' button to bring up a list of available turbulence models as in figure 7.

Select the 'LVEL' Turbulence model from it.

Click on 'OK'.

Click on 'Top menu'.

Click on 'OK'.


Figure 7: The 'Turbulence Models' page of the Main Menu.

Now the user should have returned to the main VR Editor screen, and the graphics screen should look like figure 8. (If the image does not appear correct, click on the pull-down arrow next to the 'R' icon on the toolbar; then 'Fit to window'.)


Figure 8: The domain with its size set.

b) Next, create the first object, which will act as a blockage in the flow domain.

To create a fence across the flow domain in the y-direction:

Click on the button on the Control panel (or on the toolbar), this will open the Object management panel (OMP). From the Object menu choose the option New -> 'New object'. A new object will then be created at the origin of the domain and the object dialog will be opened. This will display the dialog box shown in figure 9.


Figure 9: The Object dialog Box.

Change name to 'FENCE'.

Go to the dialog page titled 'Size', set the size of object as:
X: 0.1
Y: tick 'To end'
Z: 0.25

Now go to the dialog page titled 'Place', set the position of object as:
X: 0.3
Y: 0.0
Z: 0.0

Return now to the 'General' dialog page

Define 'TYPE': 'BLOCKAGE' (default).

To set the material properties for the fence, click on 'ATTRIBUTES', click on 'Other Materials', then on 'SOLIDS', then 'OK', followed by 'ALUMINIUM' and 'OK'.

Click on 'OK' to return to the Object dialog Box, and then on 'OK' to close the Object dialog Box. The VR Editor screen should appear as in figure 10.


Figure 10: The fence object.

c) Now create another object, which will serve as an additional blockage in the flow domain.

To create a blockage in the form of a cylinder, do the following:

From OMP choose the menu item 'New Object'.

Change name to 'CYL'.

Go to the dialog page titled 'Size', set the size of object as:
X: 0.1
Y: 0.1
Z: tick 'To end'

Now go to the dialog page titled 'Place', set the position of object as:
X: 0.0
Y: 0.0
Z: 0.0

Next, Go to the dialog page titled 'Shape'

In 'Geometry', select PUBLIC\SHAPES\CYLINDER.JPG, and click 'OK' on the Geometry Import dialog which opens.

Return now to the 'General' dialog page

Define 'TYPE': 'blockage' (default).

To set the material properties for the cylinder:

Click on 'ATTRIBUTES', 'Other materials', 'OK', 'SOLIDS', 'OK' followed by 'ALUMINIUM' and 'OK'.

Click on 'OK' to return to the Object dialog Box, and then on 'OK' to close the Object dialog Box. The VR Editor screen should appear as in figure 11.


Figure 11: The fence and cylinder objects.

d. Next, an array of cylinders will be created from the first cylinder.

First, the cylinder just created will be used to make two more cylinders for a total of three. To accomplish this:

The cylinder should already be the current object - it should be outlined in white and highlighted in the OMP. If it is not, click on it in the VR Editor graphics window or the OMP. The outline of the cylinder facets will turn white indicating that it has been 'selected' for further editing.

Click on the 'Duplicate using array' button on the hand-set (see figure 3b) or window tool bar and set DIMENSION and PITCH as:

DirectionDimensionPitch
X10.0
Y30.4
Z10.0

DIMENSION is the number of repetitions in a direction. PITCH is the distance between origins. Click on 'OK' Three cylinders should now appear in place of the original cylinder in the graphics window, as shown in figure 12.


Figure 12: The three cylinder objects.

Now the three cylinders will be grouped so they can be moved together:

At this point the final object in the array, CYL_4, should now be highlighted in the Object management panel. To create the group highlight the objects from CYL through to CYL_4. This is done through familiar windows techniques; while CYL_4 is highlighted, hold the shift key down then click on the line containing CYL. This should then highlight all the lines and hence objects between these two objects. The current group consists of the highlighted objects. See figure 12a.


Figure 12a: The three cylinder objects grouped.

The group may be move to a specified location by entering a new position on the control panel (see figure 3b). Set the X position to 0.60 and Y position to 0.04. The geometry should now look as in figure 13.


Figure 13: The array of cylinders moved to new position.

e) Next, an inlet to the flow domain will be created.

To create an inlet to the domain:

From OMP choose the menu item 'New Object'.

Change name to 'INLET'.

Set the size of object as:
X: 0.0
Y: tick 'To end'
Z: tick 'To end'

Go to the dialog page titled 'Place'

Set the position of object as:
X: 0.0
Y: 0.0
Z: 0.0

Return now to the 'General' dialog page

Define Type as Inlet.

Click on 'ATTRIBUTES' and set velocity in x-direction to 10.0 m/s.

Click on 'OK' to close the Object Attributes menu, and on 'OK' in the Object dialog Box.

f) Next, an outlet from the flow domain will be created:

To create an outlet from the domain:

Note: The inlet object should already be selected now because settings have just been made for it. If however, it is not then click once on its image in the editing window or OMP to select it.

Click on the 'Duplicate object or group' button , the 'OK' to allow the duplication. There should now be two identical inlet objects, the original hiding under the copy (i.e. the copy is currently selected). Click the X position up button until the copy of the inlet has moved right to the other end of the domain. Now, rename it and redefine it as an outlet, by double clicking on it in the graphics window and in its Object dialog Box:

Change the name to 'OUTLET'. Then,

Define 'TYPE': 'outlet'.

Click on 'ATTRIBUTES' and leave the default values as found. Click on 'OK'.

Go to the dialog page titled 'Place'

Set the position of object as:
X: tick 'At end'
Y: 0.0
Z: 0.0

The final geometry should appear as in figure 1.

Note the 'pin' on the inlet object. This is a flow direction indicator. Flow travels along the shaft of the pin towards the head. In this case it shows that flow is entering the domain from the left as expected.

g) To set the solver parameters:

Click on Main menu, on 'Numerics', then on 'Total number of iterations'.

Set the number of iterations (also called 'sweeps') in this window to 200.

Click on 'Top menu'.

Click on 'OK'.

h) Next, a point in the flow domain should be set where the flow variables can be probed or monitored as the solution runs.

To set the monitor location:

Click on the probe icon on the toolbar or double-click the probe itself, and move the probe to X=0.5, Y=0.5, Z=0.25

The monitor point is shown as the pencil (probe). It can also be moved interactively with the X/Y/Z position up and down buttons, as long as no object is currently selected.

i) Check the grid

Click on the 'Mesh toggle' button. The default mesh will appear on the screen.


Figure 13a: The default grid

As was mentioned earlier, this mesh is good for the first few runs when trends can be established. It should eventually be refined for a more accurate solution.

Running the example.

The PHOENICS solver is called Earth. To run Earth, click on 'Run', then 'Solver', then click on 'OK' to confirm running Earth. These actions should result in the PHOENICS Earth screen appearing.

As the Earth solver starts and the flow calculations commence, two graphs should appear on the screen. The left-hand graph shows the variation of pressure and velocity at the monitoring point that was set during the model definition. The right-hand graph shows the variation of errors as the solution progresses.

Figure 14 is an example of these graphs from a typical EARTH solution sequence.


Figure 14: An example of an EARTH run screen.

As a converged solution is approached, the values of the variables in the left-hand graph should become constant. With each successive sweep number, the values of the errors shown in the right-hand window should decrease steadily.

Runs can be stopped at any point by following the procedure outlined below.

Please note: If the solver is stopped before the values of the variables in the left-hand graph of the convergence monitor approach a constant value, the solution may not be fully converged, and the resulting flow field parameters which have been calculated may not be reliable.

The VR Viewer.

The results of the flow-simulation can be viewed with the PHOENICS VR post-processor called VR Viewer. This section provides a brief introduction to the capabilities of the VR Viewer.

What the VR Viewer can do.

In the VR Viewer, the results of a flow simulation are displayed graphically. The post-processing capabilities of the VR Viewer that will be used in this example are:

How to access the VR Viewer.

To access the VR Viewer, simply click on the 'Run' button, then on 'Post processor', then 'GUI Post processor (VR Viewer)' in the PHOENICS-VR environment. When the 'File names' dialog appears, click 'OK' to accept the current result files. The screen shown in figure 15 should appear.


Figure 15: The VR Viewer screen for this case                                                                                                          VR-Viewer hand set

The VR Viewer screen picture and hand set control buttons.

At first glance, the VR Viewer looks very similar to the VR Editor. There are however differences in the controls and graphics-window annotations that allow the viewing of results in the flow domain, for example:

To the left of the graphics window appears a coloured list of numbers. This is the colour scale, which corresponds to the currently-selected result variable. The colours associated with the numeric values on the scale are those that will be used when plotting flow vectors, contour plots, iso-surfaces and streamlines.

A results probe can be used to query the flow domain for values of any selected result variable that has been solved for with the Earth solver. The single number that appears at the top right of the viewing window indicates the value of the selected results variable at the current probe position. The current probe position is indicated in the graphics window by the red pencil-like probe icon. The probe position can be changed by using the 'probe position' arrows located in the lower portion of the larger handset. These 'probe position' controls work much like the 'position' controls that were used to position objects in our earlier example in the VR Editor section of this document. The probe can also be moved by clicking on the probe icon on the toolbar or double-clicking the probe itself and using the dialog that appears.

A black rectangle cuts through the flow domain. This rectangle indicates a results-viewing plane that passes through the probe location. If the background colour is dark, the outline of the viewing plane will be white. Flow vectors and results contours can be plotted on this viewing plane. The orientation of this viewing plane can be changed by using the three 'viewing plane control' icons marked X, Y and Z, located toward the centre of the control panel. Once an orientation for the viewing plane has been chosen, the 'Probe position' controls can be used to move the probe and the associated viewing plane through the flow domain.

Vectors, contours and iso-surfaces can be plotted by using the three icons located to the left of the 'viewing plane control icons'. Vectors, contours and iso-surfaces are all coloured by reference to the current variable. The value used for iso-surfaces is the value of the current variable at the probe position. Thus, moving the probe will cause vectors, contours and iso-surfaces to be redrawn appropriately.

Streamlines can be plotted up- or downstream (or in both directions) from the current probe position. Multiple streamlines can be created by started along a line or around a circle.

A brief description of the control buttons of the VR Viewer is shown in figure 16.


Figure 16: The viewing controls of the VR Viewer hand set.

These icons can be made to appear on the toolbar if the Viewer hand-set is closed.

Viewing the results with VR Viewer.

The simple flow simulation just completed can now be viewed by obeying the following instructions:

Start by selecting Y as the viewing plane by clicking on the 'Slice direction Y' button. Now click on the 'Select velocity' button followed by the 'Vector toggle' . This will display velocity vectors on the current result plane.

Use of the probe Y-position arrow buttons will shift the location of the result plane along the y- axis.

Pressure contours can be viewed by first clicking on the 'Vector toggle' to turn off the vector display mode and then clicking on the 'P' (Select pressure) button to set the current results variable to pressure. Next, click on the 'Contour toggle' . Contours of pressure are then displayed on the current result plane.

A velocity iso-surface can be obtained by first clicking on the 'Contour toggle' to turn off the plane of contours and then by clicking on the 'V' (Select velocity) button, followed by clicking on the 'Iso-surface toggle' . This will display a surface of constant velocity known as an velocity iso-surface. The value of the iso-surface will be the velocity, which exists at the current probe position. To obtain iso-surfaces of different velocity values, the position of the probe will need to be adjusted.

Typical displays of a vector, contour and an iso-surface plot are shown below in figures 17 a - c respectively.


Figure 17a: A typical vector plot.

Figure 17b: A typical contour plot.

Figure 17c: A typical iso-surface.

Now experiment further with the rest of the control buttons, so as to learn how to zoom in and out, rotate etc.

To see the velocity distribution on the surface of the middle cylinder (CYL_3), click on it to select it. Right-click to show the context menu, and select 'Surface contour'. Click on the graphics window background to de-select CYL_3. The surface contour should appear as in figure 17d.


Figure 17d: Surface Contour of Velocity

To display a 'tube' of streamlines, change the plotting plane to X by clicking on the 'Slice direction X' button. Move the probe nearer to the inlet, around X = 0.095. Click on the 'Streamline' button to bring up the Streamline Management dialog. The first time the Streamline dialog is opened, it will go straight to the 'Options' dialog. In the section 'Streamline start' click on the radio button 'Around a circle'. A small circle of spheres will now appear around the probe.

These represent the starting locations for the streamlines. Click on OK to close the dialog. Now choose the Object menu item 'New' (on the Streamline Management dialog)which will generate a circle of streamlines as shown in figure 17e.


Figure 17e: A Circle of Streamlines

To return to the 'Options' dialog at a later time, select 'Object' - 'Options' from the Streamline management Dialog.

To get a graph plot of a variable along a line, click the 'Plot variable profile' button on the toolbar. On the dialog which appears, enter the start and end coordinates of the line. Enter how many points to plot, and select the variable as shown in fig 17f.


Figure 17f: The 'Graph options' dialog

When all entries are correct, click 'Plot', and the graph of the selected variable along the chosen line will appear, as in fig 17g.


Figure 17g: Pressure along the selected line

 

Printing from VR.

Screen images such as figures 17a - c can be sent directly to a printer by clicking on 'File', then on 'Print' from the main environment screen. A dialog similar to that shown in figure 18a opens.


Figure 18a 'Print' Dialog Box

Alternatively, the screen image can be saved to a file by clicking on 'File', then on 'Save window as' from the main environment screen.

When 'Save window as' has been pressed, the dialog box shown in figure 18b opens.


Figure 18b 'Save Window as' Dialog Box

The 'Save as file' dialog offers a choice between GIF, PCX, BMP and JPG file formats, and allows the image to be saved with a higher (or lower) resolution than the screen image.

The graphics files are dumped in the selected folder (directory), with the given name. In all cases, the background colour of the saved image is that selected from 'Options', 'Background colour' from the VR-Editor main environment screen.

 

Saving the input and output files

Before experimenting further, attention should be paid to the following: Any changes made in the VR Editor will overwrite the input files. Likewise any re-runs of the EARTH solver will overwrite the output files. Therefore you may want to save these files more permanently.

To accomplish this, click on 'File' then on 'Save as a case'. This opens the dialog window shown in figure 19.


Figure 19 'Save as a case' Dialog Box

All the files associated with the current simulation are copied into the selected folder, using the case name (entered into the File name data entry box) as a base to which suitable extensions are added.

To save the files for the example, create a new folder 'myproj', and save the files with the case name 'case1'.

This completes a simple simulation. The VR-Editor can be explored further by following the second example.

To quit the VR Viewer and return to the VR Editor, click on 'Run', then 'Pre processor' then 'GUI Pre processor (VR Editor)'.


4 The Second Example - Adding heat-transfer to the previous example.

Entering heat transfer data using the VR Editor.

In order to activate the calculation of a temperature field in the flow domain the following actions must be performed:

To do this, activate the VR Editor and follow this procedure:

In the VR Editor, Click on 'Main Menu'.

Click on 'Models'.

Switch 'Energy Equation' to 'ON' and select 'Temperature'.

Click on 'OK'.

Click on 'Properties'.

Click on Domain material: 'The current domain material is' dialog box.

Click on 'Gases', then on 'OK'.

Click on 'Air using Ideal Gas Law, STP'.

Check that 'Initialise from ambient' is turned ON. This will ensure that the initial temperature will always be set to whatever value is in the 'Ambient temperature' input box. Similarily, the initial pressure will always be taken from the 'Ambient pressure' input box. This value is relative to the Reference pressure, which is defaulted to 1 atmosphere.

Click on 'OK'.

Click on 'Initialisation'

The FIINIT Value dialog Boxes for the variables P1 (pressure) and TEM1 (temperature) are both set to AMBIENT, and are greyed out.

Click on 'Top menu'.

Click on 'OK'.

Now the model has been set up for the calculation of temperature in the flow domain. However, a heat source should be introduced into the existing simulation in order to create differences of temperature. To do this:

Click on the image of the Inlet object twice; click on 'Attributes'; the inlet temperature is set to 'Ambient', with a value of  20 C.  The supply pressure is also 'Ambient', with a value of 0 Pa relative to 1atm. Should we wish a different value for either, we can toggle 'Ambient' to 'User' and input any other value.

Reduce the velocity in the x-direction dialog box to 0.1 m/s, so as to increase the effective heat transfer of the simulation. Close the object dialog box.

Click on the image of the Outlet object twice; click on 'Attributes'; the External temperature is set to 'User-set', and value is 'Ambient'  20 C.The external pressure is 'Ambient',with a value of 0 Pa relative to 1atm. Should we wish a different value for either, we can toggle 'Ambient' to 'User' and input any other value. Close the object dialog box. 

Click on the fence object twice; click on 'Attributes'; click on 'Energy source', then on 'Fixed Heat Flux', then on 'OK'. Now enter '500' in the Value dialog box. Close the object dialog box. The image of the fence should turn red, to indicate that a heat source is attached to this object.

Now the simulation can be re-run with the addition of heat transfer in the calculations. To do this:

Choose Solver from the PHOENICS-VR environment Run menu, and confirm running Earth when prompted.

Once the Earth run has finished, return to the VR Viewer by clicking 'VR Viewer' from the PHOENICS-VR environment Run menu.

 

Viewing the results with VR Viewer.

The VR Viewer can now be used as before to display the temperature results. In figure 20, a contour plot of the temperature field is shown. Note that the temperatures can also be shown inside blocked regions as these participate in the heat transfer.


Figure 20: Example of temperature contours.

In this case, the fence object is hiding the temperature field inside itself. To make the temperature visible, click on the fence object to select it; then click on the 'Hide object' button to hide it. Alternatively, click on the 'Wireframe toggle' button to display all objects as wire frames. The effect of this is shown in figure 21.


Figure 21: Example of temperature contours in Wire frame

 


5 The Third Example - Changing the computational grid in VR.

In this section, the computational grid distribution will be adjusted in the x and y directions.

Entering data in the VR Editor.

To view the flow domain regions and existing grid, follow the instructions below:

Click on the 'Mesh toggle' on the hand set to view the following:

The orange lines divide the x-direction into 5 regions and the y-direction into 6 regions; see figure 22. The blue lines are the remaining grid lines. The default grid is uniform in each region. The mesh is displayed at the probe position (in this case at Z=0.5m), in the plane which is nearest to being perpendicular to the view direction. It is clear that the cylinders are not well represented.


Figure 22: Display of regions in the domain.

The grid will now be modified. In the y-direction, the auto-mesh settings will be changed to double the grid. In the x-direction the grid will be adjusted manually going from the left of the picture to the right, in the positive x-direction as follows,

To achieve these different grid spacings:

Click on the first X-region. This will bring up the dialog box shown in figure 23.


Figure 23: Grid Mesh Settings Dialog Box

Click on 'X-Auto' to switch it to 'X-manual'.

Click on 'X-direction' next to 'Edit all regions in' near the bottom of the dialog. The dialog shown in Figure 23a will appear.


Figure 23a: Edit All Regions in X Dialog Box

Change the settings for each region as shown in Figure 23b:


Figure 23b: Modified Edit All Regions in X Dialog Box

Click on 'OK'.

Click on 'Y-direction' next to 'Edit all regions in' near the bottom of the dialog. The dialog shown in Figure 23c will appear.


Figure 23c: Edit All Regions in Y Dialog Box

Change the 'Max cell factor' from 0.05 to 0.025 and click 'Apply'. The largest cell will now be 0.025 times the domain size in Y, giving roughly 40 cells as opposed to 0.05 times the domain size which gave roughly 20 cells.

Click 'OK' to close this dialog, then 'OK' to close the Grid Mesh Settings dialog.

The grid distribution in the x and y directions should now appear as shown in Figure 24.


Figure 24: Display of refined grid in the x and y directions.

You should relate what has just been done within each region to the grid distribution created.

The desired computational grid modifications are now complete. To complete this new simulation, re-run EARTH as before by clicking on 'Run' then 'Solver'.

Viewing the Results with VR Viewer.

On completion of the simulation, the temperature field can be viewed as before using the VR Viewer by ;

From the PHOENICS-VR environment:

Click on 'Run', then 'VR Viewer'.

Click on the 'select temperature' button.

Click on the 'contour toggle'.

You are now encouraged to answer the following questions: Does the new grid affect the speed of convergence of the calculations? Does the new grid affect the temperature field found in the flow simulation?


6 Further Information

Information about VR and the PHOENICS-VR environment.

The examples which have been worked through in this document demonstrate only a few of the many facilities available to the user in PHOENICS-VR environment and VR Editor/Viewer. This section lists where to obtain more information on these interfaces.

Bubble-help in VR Editor/Viewer handset.

In VR Editor and VR Viewer, information on the various handset control buttons can be displayed when the cursor is held stationary over any relevant control button.

Help in the Main Menu of the VR Editor and Object dialog boxes.

The following additional on-line help is available in the Main Menu of the VR Editor:

Click on the 'Help' button in the top menu for help on the Main Menu.

Click on the '?' in the top-right corner of any dialog box, then click on any input window or button to get information on the parameter which is set in it.

VR tutorials.

'POLIS' is the PHOENICS On-Line Information System. In POLIS, there are several tutorials, which are all written in a similar step-by-step fashion to this document. They can be accessed on-line by:

From the PHOENICS-VR environment,

click Help, then POLIS.

Click on How to Learn

click on The VR Tutorials

HELP Button on VR-Environment Top menu.

The Help button on the Help menu leads directly to the documentation section of POLIS. The POLIS button leads to the top page of POLIS.

TR/326 PHOENICS-VR Reference Guide

This document contains descriptions of all the menus and dialog boxes available in PHOENICS-VR.

Information about PHOENICS in general.

Information about PHOENICS in general can be accessed from the PHOENICS-VR environment by:

Click Help, then POLIS.

Click on the entry 'PHOENICS Overview'.

More information, including tutorials and examples, is available from the PHOENICS Commander


7 Figures

Figure 1. The geometry to be created
Figure 2: The PHOENICS-VR Environment screen
Figure 2a. The file menu

First example:

Figure 3a: Movement controls of the VR Editor Hand Set
Figure 3b: Main controls of the VR Editor hand set
Figure 4. The top data-input menu
Figure 5. Domain settings
Figure 6: The 'Models' page of the Main Menu.
Figure 7: The 'Turbulence Models' page of the Main Menu
Figure 8: The domain with its size set.
Figure 9: The Object dialog Box.
Figure 10: The fence object.
Figure 11: The fence and cylinder objects.
Figure 12: The three cylinder objects.
Figure 12a: The three cylinder objects grouped.
Figure 13: The array of cylinders moved to new position.
Figure 14: An example of an EARTH run screen.
Figure 15: The VR Viewer screen for this case .
Figure 15a: VR-Viewer handset
Figure 16: The viewing controls of the VR Viewer hand set .
Figure 17a: A typical vector plot.
Figure 17b: A typical contour plot .
Figure 17c: A typical iso-surface.
Figure 17d: Surface Contour of Velocity
Figure 17-st: Streamline options
Figure 17e: A Circle of Streamlines
Figure 17f: The 'Graph options' dialog
Figure 17g: Figure 17g: Pressure along the selected line
Figure 18a 'Print' Dialog Box
Figure 18b 'Save Window as' Dialog Box

Figure 19 'Save as a case' Dialog Box

Second example:

Figure 20: Example of temperature contours.
Figure 21: Example of temperature contours in Wire frame

Third example:

Figure 22: Display of regions in the domain.
Figure 23: Grid Mesh Settings Dialog Box
Figure 24: Display of refined grid in the x-direction.

Contents List