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 jack2000 June 4, 2007 23:16

Could anybody explain to me wh

Could anybody explain to me why in the tutorial (pitzDaily)of SimpleFoam solver, the dimensions of pressure is:
dimensions [0 2 -2 0 0 0 0];

But based on Henry's explanation
________________________________________
By Henry Weller on Wednesday, June 01, 2005 - 07:49 am: Edit Post
> Excuse me, Henry, isn't pd = p - g*h ?

No pd = p - rho*(g.h) and you can calculate p from pd using this expression. Notice the dimension of pd:

dimensions [1 -1 -2 0 0 0 0];

h is the position vectors of the cell centres and g is the gravitational force vector.

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I am confused by that.
If I need to use pressure as my inlet boundary, should I use Pd/rho? Thanks.

Jack

 jackdaniels83 June 5, 2007 03:51

the p in that case is p/rho.

the p in that case is p/rho.

formula: p [kg/(m*s²) / rho [kg/m³] = p' [m²/s²]

Daniel

 zakifoam June 5, 2007 03:56

Hi Jack, There are two type

Hi Jack,

There are two types of pressure used in OF. The first is dynamic pressure, the dimension of which is kg/(ms2) or [1 -1 -2 0 0 0 0]. The second is kinematic pressure [0 2 -2 0 0 0 0], which is simply dynamic pressure divided by density. If you are not sure which pressure you are dealing with, you can always refer to *Foam.cfg file in directory FoamX. There you can find which pressure is used, under the entry 'fields'.

zaki

 jack2000 June 5, 2007 10:24

Thank you very much, Daniel an