Encyclopaedia Index

Developments in PHOENICS during 1994; 31.03.94;

Warning: This file is made accessible for historical interest. It does not represent the current (1999) situation.

  1. Physical models                                    
  2. Computational methods                                  
  3. Utilities and interfaces                               
  4. Distribution methods                                  
  5. Other                                                      

1. Physical models

    1.1 The new length-scale predictor
    1.2 The LVEL turbulence model
    1.3 The RNG model
    1.4 Low-Reynolds number turbulence models
    1.5 The two-scale kinetic-energy model
    1.6 The two-layer model

1.1 The new length-scale predictor

This new feature permits the calculation of distance from wall and distances between walls economically. It is useful for turbulence models such as mixing-length, Prandtl one-equation, LVEL, and many low-Reynolds-number models.

It is described in the Encyclopaedia under the heading :
             DISTANCE from the wall.

A (core) library example illustrating its use is case 290.

1.2 The LVEL turbulence model

This new feature deduces the effective viscosity from the local velocity and the distance from the wall.

It is especially useful when the space is "cluttered", ie there are so many solids immersed in the fluid that the grid cannot be fine enough for a differrential-equation model to be meaningful.

It is described in the Encyclopaedia under LVEL.

A (core) library example illustrating its use is case 290.

1.3 The RNG model

The high-Reynolds-number form of the RNG model has been incorporated and exemplified in the Advanced-Turbulence-Models Option Library.

It is described in the Encyclopaedia under RNG.

Examples of its use are to be found in the Advanced Turbulence Model     Library.

1.4 Low-Reynolds number turbulence models

Several such low-Re versions of KE-EP have now been included. Among them are:

See Encyclopaedia items, and also Advanced-Turbulence-Model Library

1.5 The two-scale kinetic-energy model

See Encyclopaedia items, and also Advanced-Turbulence-Model Library

1.6 The two-layer model

See Encyclopaedia items, and also Advanced-Turbulence-Model Library

2. Computational methods

    2.1 EARTH-generated wall functions
    2.2 Extended multi-blocking and fine-grid embedding
    2.3 Colocated-variables extension
    2.4 Alternative discretization methods for convection and diffusion.
    2.5 Parallelization progress

2.1 EARTH-generated wall functions

Earlier versions of PHOENICS, when used for conjugate heat transfer problems, generated a burdensome conglomeration of patches. These are rendered unnecessary by the the EGWF feature, which calculates all the flow resistances at solid-fluid-interfaces internally.  

EGWF = T in the Q1 does it all. No more CONPORs!

See Encylopaedia item EGWF.

A (core) library example illustrating its use is case 290.

2.2 Extended multi-blocking and fine-grid embedding

PHOENICS 1.6 already possessed "grid-restructuring" capabilities which could be used for economically fitting awkwardly-shaped domains and for embedding fine grids within coarser ones (See, for example, the "active-demonstration" series).

These have been refined and improved for PHOENICS-2.0; but much greater advances are being supplied with PHOENICS-2.1, to be issued at the end of April.

Specifically:

  1. whereas the earlier re-structuring method involved the use of   "over-lapping" cells, the new method allows for edge-to-edge contact.
  2. Further, instead of the long-familiar staggered grid and solution for velocity resolutes at cell boundaries, the solution for "co-located velocity resolutes".
  3. The third departure from previous practice which has rendered the multi-block method efficient is reliance on the conjugate-gradient solver instead of the long-standard Stone-type solver.

This change has been brought about with very little internal change to the logic and storage arrangements of PHOENICS, which still "thinks" it is a structured-grid code.

Some simple "passive-demonstrations" can be viewed as option k of hlp.

Some multi-block grids can be seen by entering: Q, then F,  then  d_grids/mb1 d_grids/mb2  d_grids/mb3    d_grids/mb4

2.3 Colocated-variables extension

2.4 Alternative discretization methods for convection and diffusion.

2.5 Parallelization progress

CHAM is participating in EEC-supported Projects PASHA, EuroPort and SHIPS; and it has also been collaborating with Southampton University's Parallel Application Centre.

As a consequence, PHOENICS-2 has now been successfully ported to:-

  1. the Distributed Array Processor of Cambridge Parallel Computing (formerly call Active Memory Technology);
  2. several multi-transputer computers manufactured by Parsytech GmbH;
  3. clusters of IBM RS 6000, and other, work-stations.

The ports to (1) and (2) make use of domain-decomposition techniques which have been found to give excellent efficiency.

3. Utilities and interfaces

    3.1 The CHEMKIN interface
    3.2 The IGES interface
    3.3 New grid-generation features
    3.4 The Q1 interpreter
    3.5 HLP
    3.6 The phi-file stripper

3.1 The CHEMKIN interface

A new interface has been written (by JK Worrell of CHAM) which connects PHOENICS with the public-domain code CHEMKIN created by the Sandia Laboratories. It is a PHOENICS add-on, and is supplied with a special library of Q1's.

See: "About PHOENICS-2" items in "description of modules", "how to run", and "FORTRAN files".

3.2 The IGES interface

See: About PHOENICS-2 items in description of modules, how to run, and FORTRAN

3.3 New grid-generation features

3.4 The Q1 interpreter

This feature, which has existed in primitive form for at least one year, has been upgraded.

Enter LOAD(20) at the SATELLITE command prompt to try is out.

It is capable of much extension, especially by users.

3.5 HLP

A set of DOS utilities is provided when HLP is typed.

If users like the idea, many more can be provided.

HLP is not "fancy"; but it is quick, and easy to extend.

3.6 The phi-file stripper

3.7 Menu improvements

GENERAL-menu improvements December 1993

For PHOENICS Version 2.0 General Menu has undergone some fundamental changes in the way it operates and was enriched by many new features:

4. Distribution methods

PHOENICS is now being distributed in three distinct manners:

See item: How to acquire.., under About PHOENICS-2.

Note: There are opportunities for experienced academic PHOENICS users to participate in (and profit from) the PHOENICS-Plus distribution effort.

5. Other