Encyclopaedia Index

8. What is special about EXPLOITS; performing the simulations


    8.1 Special physics
    8.2 Special mathematics
    8.3 The choice of where to compute
    8.4 Built-in and human-supplied expertise
    8.5 SHARREC; SHAring Resources REduces Costs

8.1 Special physics

In addition to possessing or having access to all the models of turbulence, chemistry and radiation which have proved useful in CFD, EXPLOITS-PHOENICS has several new ones of its own, namely:

  1. the LVEL model for calculating the effective viscosity and diffusivity in an enclosure in which numerous solids are immersed;

  2. the Multi-Mluid Model which is capable of representing turbulent flames with greater realism than hitherto, and which allows for population-grid refinement so as to establish numerical accuracy;

  3. the IMMERSOL model of radiation between and heat-conduction within numerous solids immersed within a heat-transferring fluid.

  4. Further, PHOENICS is able to predict the stresses and strains in the immersed solids, whether these are thermally or mechanically induced.

Availability is one thing; utilisatiion and validation are others.

Because of their novelty, none of these models have a track record, whether good or bad, as long as k-epsilon, eddy-break-up and six- flux models of mixing, combustion and radiation respectively.

The new models do however possess the merits of:

What is mainly needed is systematic use and testing.

This requires the application of external funding.

8.2 Special mathematics

EXPLOITS-PHOENICS performs its calculations in a way which has proved economical for use on "parallel computers", whether of the shared- memory or distributed-memory kinds.

The technique used is called "domain decomposition". In oil-platform terms, this implies that the whole module is cut into imaginary slices, to each of which a PHOENICS-carrying processor is devoted.

Parallel-PHOENICS has been code-named SORCERER, to evoke the images of Disney's Sorcerer's Apprentice, in which row upon row of identical broom-sticks are seen fetching and pouring out buckets of water.

This feature is important, because it permits explosion simulations to be performed with computational grids which are fine enough to represent adequately the geometrical complexities of equipment- filled oil platforms.

8.3 The choice of where to compute

(a) Hardware

EXPLOITS-PHOENICS can run adequately on:-

  1. Pentium-based Personal Computers;
  2. Work-stations, and work-station clusters;
  3. Cray-type supercomputers;
  4. Multi-processor parallel computers.


CHAM's MICA project is therefore directed to making super- and parallel-computing power accessible to, and affordable by all.

(b) MICA

MICA is an acronym which stands for Model for Industrial CFD Applications. It is partially funded by the European Commission as part of the ESPRIT Framework IV Program.

CHAM is the proposer and coordinator of the project.

Other partners are: INRIA (France), U Paderborn & LSTM (Germany), LITEC(Spain), BRE & WAT&G (UK), CMR (Norway), Vattenfalls & SMHI (Sweden), NTUA (Greece), and Hoogovens & Stork-Comprimo (Holland).

The general idea is that:-

(c) The special sectors currently attended to by MICA

Ten sectors are currently receiving attention, namely:

"Environmental" group

Oil-platform explosions Smoke movement and fire spread in buildings Heating and ventilating of buildings Air and pollutant flow around assemblies of buildings Flow around marine structures

Heat-transfer-equipment group

Coal-fired industrial furnaces Glass-melting and refining furnaces Annealing furnaces Industrial ovens Steam condensers for power stations

(d) Other sectors receiving additional attention from CHAM

At the same time, CHAM is treating certain other industrial sectors in the same way, using its own funding. These are:

Other products are being planned.

CHAM's view is that an increasing proportion of the CFD needs of industry and the environment will be met in the MICA manner.

EXPLOITS is therefore not a one-off enterprise, but one of a growing family, the members of which will learn from each other.

(e) Current status

The MICA project began on Jan 1 1996, and will finish on Dec 31, 1997.

The first year is being devoted to collection and assembly of all the components.

The second year will be devoted to testing, validation, publicity, and the enlargement of practical use, to be followed by a commercial launch.

However, the MICA doors are open now to users who wish already to make use of its services.

By entering early, such users not only have to pay lower-than-full- commercial rates (namely two-thirds of full costs); they also influence the direction of the development of the service.

8.4 Built-in and human-supplied expertise

The aims of MICA include the provision of the maximum amount of built-in expertise, so as to minimise the necessity for human intervention in respect of choosing:-

This is an aim which cannot be accomplished all at once; and it can perhaps never be so completely attained as to enable human oversight to be wholly dispened with.

It is therefore intended that, specialists in the subjects of the individual sectors shall be "on call", like consultants in a hospital, to scrutinise the input data and the results of the simulations and to send comments and advice to their originators.

8.5 SHARREC; SHAring Resources REduces Costs

PHOENICS itself is a kind of monument (without the static connotation of that word) to the SHARREC principle; for it has grown, over the years, by using the resources gained from each use of the code so as to improve the benefits which later users can enjoy.

Inter-sector transfer of capability is what "customizable" general- purpose codes such as PHOENICS are particularly good at. An example is the multi-fluid model of turbulence, which has applications in many sectors (eg chemical reactors, furnaces, reciprocating engines, gas turbines, oceanography, atmospheric physics).

Experiences gained with this model for furnaces, for example, should enable fire-spread processes to be better simulated; and it is to be hoped that collaborative studies made in connexion with oil-platform hazards may benefit CFD users in other industrial and environmental sectors.