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-   -   when use 3ddp? (https://www.cfd-online.com/Forums/fluent/43819-when-use-3ddp.html)

Txema February 20, 2007 03:41

when use 3ddp?
 
I know that 3ddp is for a 3d mesh with a double precision,
but when is it used?? I havn't found it in help. Txema

Kasper Skriver February 20, 2007 03:53

Re: when use 3ddp?
 
it is used when you wan't double precision, meaning higher level of accuracy in the computer round off.

It consume more ram and require more time i think. Give it a try and compare results if you want to see what the difference is!

BR

Kasper Skriver

sam February 20, 2007 04:28

Re: when use 3ddp?
 
what about the using dp on 64 system and windows. As indicated by joans larrson(in his thesis) (Sys Admin of cfd-online)

Razvan February 21, 2007 17:11

Re: when use 3ddp?
 
Double-precision solvers are extremely useful when dealing with very sensitive analisys like aerodynamic drag prediction, multiphase systems, pollutant formation in very small fractions in multi-species+reactions in combustion systems, porous media with high resistance coefficients on highly skewed grids, an so on.

One very important thing to know: double precision solvers on 64-bit machines (and 64-bit executables, of course) are much more easily handled than on 32-bit machines (almost same memory requirements and more important, very little difference on execution times!). So don't aviod using them if you have Opterons or 64-bit Xeons.

Razvan


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