[Nek5000-users] turbulent channel flow

[nek5000-users at lists.mcs.anl.gov]

Hi,

I am trying to reproduce the results for the turbulent channel flow
using DNS.

However, instead of using the bulk velocity or the flow rate to drive
the flow, I would like to use a mean pressure gradient.

Using the non-dimensional equations resulting from selecting the
friction velocity (u_tau) as the velocity scale, only the Reynolds
number based on u_tau needs to be specified because the mean pressure
gradient is equal to -1.
Consequently the pressure gradient in the streamwise direction is grad
p=-1+grad p* where * means fluctuation.

I assumed that this could be done by simply setting:
ffx=1.0
ffy=0.0
ffz=0.0
in subroutine userf.

All my trials initializing the flow with some kind of synthetic
turbulent flow ended up damping the fluctuation and converging towards
the laminar solution.

Any help?.

-- 
Alexandre Fabregat, PhD.

Mail: afabrega at uottawa.ca
Phone: 630 562-5800 (ext. 6293)
Office: B207

Mechanical Engineering Department
University of Ottawa
161 Louis Pasteur, K1N6N5, Ottawa ON