FLAIR Tutorial 2: A room with two radiators

This case models a three-dimensional room, consisting of two closed windows, a door. The radiators underneath each window produce a total heat flux of 500W and the walls are fixed at 20 degree C. The IMMERSOL model is used. The 'Duplicate object' function is used for the creation of the second window and radiator. The material of the radiators is selected from the property database.

The following picture shows the geometry.

Setting up the model

Start FLAIR with the default room

The FLAIR VR-Environment screen should appear, which shows the default room with the dimensions 10mx10mx3m.

Resizing the room

To activate the physical models

a. The Main Menu panel

FLAIR always solves pressure and velocities. The temperature is also solved as the default setting.

The 'Models' page of the Main Menu.

b. To activate LVEL turbulence model

c. To activate IMMERSOL radiation model

Adding objects to the room

a. add a door

X: 1.0 m

Y: 0.0 m

Z: 2.0 m

X: tick 'at end'

Y: 0.0 m

Z: 0.0 m

b. add the first window

X:0.00 m

Y:0.98 m

Z:0.87 m

X: 0.0 m

Y: 1.28 m

Z: 1.0 m

c. add the second window by duplicating the first window

X: 0.0 m

Y: 2.92 m

Z: 1.0 m

d. add the first radiator

X: 0.1 m

Y: 0.98 m

Z: 0.87 m

X: 0.0 m

Y: 1.28 m

Z: 0.0 m

e. add the second radiator by duplicating the first radiator

X: 0.0 m

Y: 2.92 m

Z: 0.0 m

f. add a vent

X: 0.3 m

Y: 0.0 m

Z: 0.27 m

X: 2.48 m

Y: 0.0 m

Z: 2.15 m

g. add the wall at x =3m

The wall object with the PLATE type is used to set the wall friction and the surface temperature. The window objects created above have the same effect.

X: 0. m

Y: tick 'to end'

Z: tick 'to end'

X: tick #at end'

Y: 0.0 m

Z: 0.0 m

h. add the wall at y =5m

X: tick 'to end'

Y: 0.0 m

Z: tick 'to end'

X: 0.0 m

Y: tick 'at end'

Z: 0.0 m

i. add the wall at y = 0

X:2.0 m

Y:0.0 m

Z: tick 'to end'

X: 0.0 m

Y: 0.0 m

Z: 0.0 m

j. add the adiabatic walls at x = 0

X: 0.0 m

Y: 1.28 m

Z: tick 'to end'

X: 0.0 m

Y: 0.0 m

Z: 0.0 m

X: 0.0 m

Y: tick 'to end'

Z: tick 'to end'

X: 0.0 m

Y: 3.9 m

Z: 0.0 m

WALLC

Size, Position

Xsiz: 0.00 m, Xpos: 0.0 m

Ysiz: 0.66 m, Ypos: 2.26 m

Zsiz: 1.87 m, Zpos: 0.0 m

 

WALLD

Size, Position

Xsiz: 0.00 m, Xpos: 0.00 m

Ysiz: 2.62 m, Ypos: 1.28 m

Zsiz: 0.83 m, Zpos: tick 'to end'

To set the grid numbers and to solver parameters

Click on the mesh toggle button, on the main control panel to view the grid distribution on the screen as shown below.

This is the default mesh created by the auto-mesher. It is adequate for the tutorial, but should be refined for a 'real' solution. Click the mesh toggle again to dismiss the grid display.

Running the Solver

To run the PHOENICS solver, Earth, click on 'Run', then 'Solver' followed by clicking 'OK' to confirm running Earth. These actions should result in the PHOENICS Earth monitoring screen.

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 solved variables at the monitoring point that was set during the model definition. The right-hand graph shows the variation of errors as the solution progresses.

To the end of the calculation, the monitoring display would be as shown below.

EARTH monitoring screen

Viewing the results

The radiation heat flux in the X direction, QRX

The radiation heat flux in the Y direction, QRY

The radiation heat flux in the Z direction, QRZ

Saving the case

Once a case has been completed, it can be saved to disk as a new Q1 file by 'File - Save working files'. The Q1 and associated output files can be saved more permanently by 'File - Save as a case'.