CFD Online Discussion Forums

CFD Online Discussion Forums (http://www.cfd-online.com/Forums/)
-   Phoenics (http://www.cfd-online.com/Forums/phoenics/)
-   -   Ground coding enquiry (http://www.cfd-online.com/Forums/phoenics/51461-ground-coding-enquiry.html)

Wenqing Zhang August 12, 2002 07:32

Ground coding enquiry
 
After reading CHAM's website on GROUND coding, I have the following enquiries:

(1) On the website it says "Group 19 is always visited" and "Group 1 of GROUND is ALWAYS VISITED at the beginning of each run". What does this "each run" exactly mean? is it a slabwise operation? a sweep? or a whole EARTH run?

(2) Due to the confusion described in (1), I am also not sure when to use the following "if" conditions in ground coding.

IF(ISTEP.GE.1.and.ISTEP.LE.LSTEP) THEN

IF(IZ.GE.1.and.IZ.LE.NZ) THEN

......

ENDIF

ENDIF

As can be seen from the ground codings in http://www.cham.co.uk/phoenics/d_pol.../plan3.htm#3.6, the above "if" conditions are used in the setting of nonlinear property in Group 9, but they are absent when setting non-linear source in Group 13.

(3) There seems no equivalent in Z direction to IXF, IXL in X direction or IYF, IYL in Y direction. Are they not necessary if we need ground coding for a source term on a PATCH as follows?

PATCH(SOR1, NORTH, 1, NX, NY, NY, 2, 5, 1, LSTEP)

Can anyone give me some tips? Many many thanks!

Wenqing Zhang

Michael Malin August 12, 2002 11:24

Re: Ground coding enquiry
 
(1)The Q1 input file can be configured to perform several runs of the earth cfd solver, i.e. a multi-run facility is available from a single q1 input file. The term 'run' refers to a single run of several runs that have been set up in the Q1 file. The multi-run is hardly ever used nowadays so I would forget about it.

(2)Normally, Group 9 and Group 13 do not require use of the IZ and ISTEP conditions. The doccumentation you refer to considers PLANT, which writes GROUND coding based on instructions provided in the Q1 file. PLANT, which I do not use, may not be intelligent enough to realise that such conditions are unnecessary in these groups.

The IZ, ISWEEP, and ISTEP conditions are most often used in Group 19.

(3) Group 13 is visited on only those IZ slabs for the PATCH is active. In your case Group 13 would only be visited for IZ = 2 through to 5. EARTH will arrange through YOUR use of the L0F function that the solved and stored variables you are using in Group 13 are for the correct IZ slab.

Wenqing Zhang August 12, 2002 11:56

Thank you, Dr. Malin!
 
Dear Dr. Malin,

Thank you very much for your prompt reply. Your reply has cleared up all my doubts.

Best regards!

Wenqing Zhang


All times are GMT -4. The time now is 17:22.