Encyclopaedia Index

WORKSHOP - Two-phase IPSA

Overview

The case below exemplifies how the IPSA method built in PHOENICS for two-phase calculations can be applied to steady boiling in pipe. The cylindrical-polar coordinate system is used and the flow is laminar. The heat source is supplied along a part of the pipe wall.

The geometry is shown below:

A complete step-by-step guide, showing how to set the case from the default mode of operation, is provided.

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.

From the commander level:

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

In PHOENICS-VR 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.

To enter VR Editor:

This is the default mode of operation.

Within VR Editor.

Set the domain size and grid numbers:

Click on 'Menu' (Main Menu) on the VE-Editor panel; and set 'Boiling in a pipe (IPSA)' as the Title.

Click on 'Geometry'.

Click on 'Cartesian' under co-ordinate system; and select 'Cylindrical-polar' and then on 'OK'.

Leave 'Inner radius' at 0.0 and 'tolerance' at 1.e-3.

Change the x-domain size to 0.1 radians.

Change the y-domain size to 0.0587 m.

Change the z-domain size to 0.375 m.

Set 'number of cells' to 1 in x-direction, 10 in y-direction and 20 in z-direction.

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

Click on 'OK' to exit from 'Menu'.

Click on 'Reset' button on the movement panel.

Click on 'Fit to Window'. You may need to click on 'zoom out' button if the geometry does not appear on the screen.

Use Arrow buttons on the movement panel to position the Z-direction of the coordinate upright and Y-direction pointing to the right, as in the picture above.

Activate solution of the required variables and models

Click on 'Menu'; and the on 'Models'.

Change the simulation from 'One phase' to 'IPSA_FULL'.

Leave 'Solution for velocities and pressure' to ON.

Click on ENERGY EQUATION; and then choose ENTHALPY and toggle STATIC to TOTAL.

Click on 'settings' for IPSA_FULL

Set the interphase coefficient (CFIPS) to 2500.

Set the interphase mass transfer coefficient (CMDOT) to HEATBL and turn 'Store' to 'ON'.

Set the interphase heat transfer coefficient (CINT) to 10 for both H1 and H2

Click on 'Previous panel'.

Specify properties

Clikc on 'Properties'.

Turn 'Use property table' to OFF.

Set the density of phase 1 to 749.94 kg/m3.

Set the density of phase 2 to 35.55 kg/m3.

Set interphase properties (PHINT) to 0.1 for H1, 1.513E6 for H2.

Set Initial values

Click on 'Initialisation'.

Set the following initial values

Set gravitational force

Click on 'Sources'.

Turn 'Gravitational forces' to 'ON'

Change Buoyance model to 'CONSTANT'

Set gravitational acceleration to -9.81 m/s2 in Z-direction.

Enter numerical settings

Click on 'Numerics'.

Set 'Total number of iterations' to 250.

Click 'Relaxation control' and set 'Automatic convergence control' to OFF

set the following values:

Click 'Previous panel'

Click on 'Limits on variables' and set VARMIN for H1 to 1.e-10.

Click on 'Previous panel'.

Click on 'Top menu' and then on 'OK' to exit from 'Menu'.

Create Objects and specify boundary conditions

Create the Inlet

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

Change name to INLET.

Click on 'Size' and set Size of the object as:

Xsize: 0.1

Ysize: 0.0587

Zsize: 0.0

Click on 'General'.

Define Type: INLET.

Click on 'Attributes'

Change the Inlet density to 'Dens*Vol Frac' (Density*Volume fraction)

Set enthalpy to -60000 J/Kg.

Set velocity in Z-direction at 2 m/s.

Click on 'OK' twice to exit from the Objectspecification Dialogue Box.

Create the heat source

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

Change name to Heater.

Click on 'Size' and set Size of the object as:

Xsize: 0.10

Ysize: 0

Zsize: 0.225

Click on 'Place' and set Position of the object as:

Xpos: 0.0

Ypos: 0.0587

Zpos: 0.15

Click on 'General'.

Define Type: PLATE

Click on 'Attributes'.

Change Energy source to 'Surface enthalpy' and set the value to 1.366E7 J/Kg

Click on 'OK' and check the position and size again.

Click on 'OK' to exit from the Object Dialogue Box.

Create the outlet

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

Change name to Outlet.

Click on 'Size' and set Size of the object as:

Xpos: 0.0 Xsize: 0.1

Ypos: 0.0 Ysize: 0.0587

Zpos: 0.375 Zsize: 0.0

Click on 'Place' and set Position of the object as:

Xpos: 0.0 Xsize: 0.1

Ypos: 0.0 Ysize: 0.0587

Zpos: 0.375 Zsize: 0.0

Click on 'General'.

Define Type: OUTLET

Click on 'Attributes'

Set Ph 1 coefficient to 20, and Ph2 coefficient to 1.0

Click on 'OK' twice to exit from the Object Dialogue Box.

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) Viewer)'. Click 'OK' on the file names dialog to accept the default files.

To view:

The image below shows the phase 2 (Steam) volume fraction distribution.

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).

Saving the results.

In the PHOENICS-VR environment, click on 'Save as a case', make a new folder called '2PHASE', select the new folder, and save as 'IPSA'.