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-   -   standard Vs PRESTO! scheme (http://www.cfd-online.com/Forums/fluent/40309-standard-vs-presto-scheme.html)

parag March 25, 2006 10:53

standard Vs PRESTO! scheme
 
If one uses standard pressure interpolation scheme & for same problem with same all other settings except now PRESTO scheme is employed then converging answers should be same or there will be a huge differnce in answers?

aliabadi May 20, 2010 12:58

Differences Between PRESTO! and Standard Pressure Discretization
 
To discretize momentum equation, one needs pressure values on the control volume faces.

Standard pressure discretization interpolates the pressure on the faces using the cell center values. On the other hand PRESTO! discretization for pressure actually calculates pressure on the face. This is possible using staggered grids where velocity and pressure variables are not "co-located".

PRESTO! discretization gives more accurate results since interpolation errors and pressure gradient assumptions on boundaries are avoided. This scheme works better for problems with strong body forces (swirl) and high Rayleigh number flows (natural ventilation). PRESTO! however, is more computationally costly, since you need more memory for "alternate" grids.

For example when you solve natural ventilation flows using standard discretization, you assume zero pressure gradient at the wall which gives erroneous velocities at the boundary, but if you use PRESTO! you account for pressure gradient at the boundary and get the correct answer.

Ronnfors August 23, 2010 08:09

Reference
 
HI!
I am currently studying different pressure schemes for multiphase flows. I try to motivate Fluent recommendation on using PRESTO!.

May I ask if you have a reference for what you wrote?

Thanks!

aliabadi August 23, 2010 14:16

Reference for PRESTO scheme
 
Hi,

Here is a reference for PRESTO! scheme

Peyret, R., 1996. Handbook of Computational Fluid Mechanics.
Academic Press Limited, USA.

Good Luck

Ronnfors August 24, 2010 02:26

Thanks!
 
Hi,

Great! Thanks!
I tried to find in Tannehill, Versteeg, Pantakar but no luck in those books!

BR
Andreas

Baran August 13, 2013 23:01

Hello there,

I wondered which section explain the PRESTO method?
I was not able to find it in the book?

Thank you
Baran


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