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]

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]

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]

Hi,

Here is a reference for PRESTO! scheme

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

Good Luck

[Ronnfors]

Hi,

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

BR
Andreas

[Baran]

Hello there,

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

Thank you
Baran