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David Sumners March 9, 2009 10:41

Storage Location in phi file

I am using a staggered grid (default in CARTs) and was interested to know what information is passed to the phi file at the end of the computation? In a staggered grid the velocity is stored at the cell face and the pressure at the cell centre...

..if the data is stored at the cell centre then this must be some sort of average. In this case, does anyone know how this is calculated and if it is possible to output data from the cell face?

Thanks in advance

Mike March 12, 2009 07:28

Re: Storage Location in phi file
I am not sure if I understand your question. For the default staggered grid, PHOENICS writes the nodal pressures and cell-face velocities to the PHI file.

David Sumners March 13, 2009 11:06

Re: Storage Location in phi file
Thanks for your response; yes this is what I was asking. I was under the impression that the outputted data was co-located. In this case, I have a further question:

For a NX*NY*NZ mesh, there are NX*NY*NZ pressure nodes (at the centre) and (NX+1)*(NY+1)*(NZ+1) velocity faces. The output in phi is an NX*NY*NZ array. For a given cell, pressure p is solved and stored at the cell centre. In 2-D; represneting the vertical and primary velocity through the cell as Ws/Wn (south and north face) and Ue/Uw (east and west face) respectively. Which velocity is stored to the same array location that corosponds to the pressure node p at the centre once saved to phi?

It would make sense that Ue and Wn is stored for the active cell but I would like confirmation of this.

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