Encyclopaedia Index

7. What is special about EXPLOITS; setting up the problem


    7.1 Geometrical-data input
    7.2 Material properties
    7.3 Models
    7.4 Boundary conditions
    7.5 Initial conditions
    7.6 Other input data

7.1 Geometrical-data input

EXPLOITS makes use of the PHOENICS Virtual-Reality Interface, which requires only basic keyboard-and-mouse skills.

This VR system is of the "non-immersive" kind, which means that no special gloves or head-sets are required.

The next picture shows the control screen which is presented to the user.

The various buttons and arrows permit the view to be controlled, and the various objects to be moved, re-sized, deleted, or duplicated. This is an illustration of how objects of various shapes and sizes are brought in and positioned.

Note the control buttons around the edges of the screen Control Screen

Placing the mouse on the appropriate arrows enables the objects to be viewed from various angles like this ...

Angle 1

Angle 2
"Clicking" on an object brings a "dialogue box" on to the screen. This enables a name to be typed, and some data to be altered.



Grids can be displayed

grid 1

and modified

grid 2

and viewed from various viewpoints


The "top-view" box assists orientation

top box

7.2 Material properties

The materials of which solid and fluid objects are composed are selected from lists which can be called into the dialogue boxes.

A "fluid object" could comprise, for example, a region in which there exists a gas mixture with a particular fuel/air ratio.

7.3 Models

The EXPLOITS Virtual-Reality Interface allows the user to select models of ignition, laminar flame propagation, turbulent mixing and turbulent combustion, through the "domain" dialogue box.

If the user makes no selection, the built-in defaults, which are usually satisfactory, will be employed.

7.4 Boundary conditions

Among the "objects" which the EXPLOITS interface can call into its virtual-reality world are inlets, outlet apertures, and sources of mass, momentum and energy.

They can be named, located, and given qualitative and quantitative attributes in the same "dialogue-box" manner as employed for solids.

The apertures may be of the "bursting-panel" character; and indeed the flow rate through them can be any non-linear function of pressure difference and time.

They may also consist of sources of gas or liquid which become active after the start of the explosion as a cosequence of the passage of the flame, or of the pressure wave which precedes it.

7.5 Initial conditions

Initial-condition "objects" are introduced in the same fashion.

They may represent the distributions of fuel-air ratio within the module; or they may define the time, location and strength of the ignition source.

The shapes of such initial-condition objects amy be box-like, ellipsoidal, cylindrical or wedge-shaped; and more conplicated shapes may be created by combinations of these.

It should also be stated that the inventory of shapes which are currently supplied can be augmented by any others for which there is sufficient demand to justify the (not very large) cost of preparing them.

7.6 Other input data

At data-input time, users may, if they wish, indicate their desire for particular pieces of information to be supplied at the end of the not-yet-started flow-simulating computation.

This is done by introducing "output objects" into the world.

This is especially advantageous when either:-