[Nek5000-users] param(2)

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

Thanks Carl Erik.

It should be p2 = \mu.   (I hadn't noticed that error in the manual.)

Examples are stand-alone entities and thus as long as they are self-consistent,
that suffices.  Thus, in turbChannel (originally set up by me), I know that rho==1,
and therefore ignore it always... such that \mu=p2==\nu, and I never bother to
divide by rho.

So, I think the answer to your question, if you want physical variables is:

p1 = rho
p2 = mu
p7 = rhoCp
p8 = conduct.

You should also then set

p21=0
p22=0

and 

p24=.01
p25=.01

These latter changes will turn off the non dimensional tolerances and tell
the iterative solvers to set the tolerances in a relative sense according to the
anticipated scale of your variables.

Paul


________________________________________
From: nek5000-users-bounces at lists.mcs.anl.gov [nek5000-users-bounces at lists.mcs.anl.gov] on behalf of nek5000-users at lists.mcs.anl.gov [nek5000-users at lists.mcs.anl.gov]
Sent: Wednesday, January 18, 2017 8:07 AM
To: nek5000-users at lists.mcs.anl.gov
Subject: [Nek5000-users] param(2)

Hi all,

There seems to be some inconsistencies regarding dynamic (\mu)/kinematic
(\nu) viscosity in nek:

- The manual says that P002 is kinematic viscosity (\nu)
- param(2) is stored in VDIFF, which is split by nu_star in split_vis
- In the turbChannel example, param(2) is added to the Dynamic
Smagorinsky term, which has dimension m^2/s, as has \nu

On the other hand:
- MAKEVIS is stated to calculate 2*DEL*[mue*(S ....)], using VDIFF_E
- The manual says about P008: mavier5.f: param(8) = param(2) ! conduct =
dyn.visc.
- \mu is listed as a parameter in Chapter 3.3.1 of the manual, regarding
the .rea file.

In all the examples, param(1) = 1, so \nu = \mu, but for some physical
cases it is convenient to keep the dimensional variables.

So what is the correct use of param(2)?

Thanks,
Carl Erik,
FFI, Norway


_______________________________________________
Nek5000-users mailing list
Nek5000-users at lists.mcs.anl.gov
https://lists.mcs.anl.gov/mailman/listinfo/nek5000-users