[Nek5000-users] Problem when running with variable fluid properties

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

Thanks a lot Antonio,

Indeed you are right the name even suggests udiff for diffusion term. I'll fix it asap.
Oana
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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, March 30, 2016 12:43 PM
To: nek5000-users at lists.mcs.anl.gov
Subject: Re: [Nek5000-users] Problem when running with variable fluid   properties

Hi again, NEK users.

I think I have found the problem. Following the table on page 17 of http://nek5000.github.io/NekDoc/Nek_users.pdf, I was mistakenly setting density in udiff and viscosity in utrans (field=1). Please correct this typo in the manual. NEK examples are however correct.

Regards
Antonio

2016-03-15 20:14 GMT+01:00 ANTONIO ANTORANZ PERALES <anantora at ing.uc3m.es<mailto:anantora at ing.uc3m.es>>:
Hi,

After successfully running some DNS cases of a turbulent pipe with heat transfer in NEK (http://www.sciencedirect.com/science/article/pii/S0142727X15000533), I am now struggling to run a similar case but with variable fluid properties (Re and Pe being functions of temperature).

I am currently using Pn-Pn2 (lx2=lx1-2 in SIZE) method and stress formulation (IFSTRS=true), together with IFUSERVP=true (p030=1.0 in REA file) to be able to define the viscosity and conductivity functions. Initial flow conditions are taken from a previous constant fluid properties turbulent pipe case.

My problem is that, when setting IFUSERVP=true, the flow velocities go to zero in very few time steps, even though I was setting constant fluid properties in USERVP subroutine for trial purposes.

I have checked that the forcing in the momentum equation (subroutine USERF) is correctly set.

Could you please give me some indications as to what I can be doing wrong? Thanks in advance.

Regards
Antonio



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ANTONIO ANTORANZ PERALES
Universidad Carlos III de Madrid



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ANTONIO ANTORANZ PERALES
Universidad Carlos III de Madrid