[Nek5000-users] Convergence problem in 2D square cylinder

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

Dear Victor,

Do you have sufficient boundary layer resolution near your cylinder?
You'll want to have a relatively thin layer of elements surrounding the cylinder.

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: Friday, January 13, 2017 5:48 AM
To: nek5000-users at lists.mcs.anl.gov
Subject: [Nek5000-users] Convergence problem in 2D square cylinder

Dear Nek users,

I am a PhD student at School of Aeronautics and Astronautics, Technical
University of Madrid, Spain.
I am really interested in using Nek5000 in order to generate a flow
field database. After that, I will apply reduced order modelling
techniques. The final goal is to study the reduced order models and to
investigate possible ways to speed up the calculations.

My first run in Nek5000 is bidimensional flow over a square cylinder for
low Reynolds numbers (Re = 100). Sadly, I am getting some convergence
problems, Courant number grows up and explodes in a few iterations.
Plotting the velocity fields, I have noticed that the velocity near the
square cylinder corners is very big compared to what should be expected.

Anyone has any recommendation? Is there any way to introduce artificial
viscosity or to increment dissipation?

Regards,

VBeltranM

--
Víctor Beltrán Martínez
Ph.D. Student in Applied Mathematics
Escuela Técnica Superior de Ingeniería Aeronáutica y del Espacio
Universidad Politécnica de Madrid

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