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Subject: Re: Ansys FSI nightmare
Author: Christopher Astefanous
Date: 2008-04-25 20:44:57Tan,
I have no answers for you, but I can't help but comment. First off,
where is your dissertation advisor on this? (Is this for PhD or
Masters?)
If you don't get your dissertation in by the deadline, you have next
semester to do it, don't you? Hopefully, that's the case. You can relax,
it'll be a big pain but it won't be the end of life.
Secondly, with 1 week to go you now ask can ANSYS even solve this type
of problem? Have you tried breaking apart the problem iteratively? Like
I said before I have no answers for you as I have not worked with CFD.
Yet, can you manually iterate the coupled problem, i.e., Solve for the
geometry, set your geometry as fixed, solve for the flow field and
internal pressure, apply the pressure, resolve for the geometry. Instead
of trying to have ANSYS solve the coupling on its own. It sounds like
the degree of non-linearity is very difficult to over come since the
buckled shape will continually change as the internal pressure/flow
field changes in a flexible pipe.
Confused,
Christopher Astefanous
Frequency Electronics
-----Original Message-----
From: xansys-bounces_at_xansys.org [mailto:xansys-bounces_at_xansys.org] On
Behalf Of Y Y Tan
Sent: Friday, April 25, 2008 4:30 PM
To: xansys_at_xansys.org
Subject: [Xansys] Ansys FSI nightmare
Hi guys,
Its now 1 week away from my dissertation deadline, I have posted up my
problem
several times and people here have helped me clarify alot of things.
Yet, I
still can not get the results that I want, I really feel that my FE
skills are
letting me down or maybe its just how i approach things. I have ran my
FE model
for almost 300 times now for the past few months and I have really ran
out of
ideas what I can do.
Let me just explain my model again, I have a circular pipe, with a
steady state
laminar flow through it. The pipe walls are flexible and an external
pressure
is applied onto the pipe walls. Because the external pressure is greater
than
the internal pressure of the fluid, the pipe will buckle inwards and
because of
that, the flow will have to squeeze through the constriction and the
local
pressure will drop because of Bernoulli, and as a result the pipe will
further
deform. This is a highly non-linear and highly coupled problem.
My question is, can Ansys actually solve this type of problem? I am
currently
using MFX and doing the sequential analysis where I run CFX first before
I run
Ansys. Would a simultaneous analysis be a better option?
I'm about to burst out in tears as I write this post, I really really
hope that
someone here could understand the situation which I'm going through and
help me
go through this modelling problem and consequently help save me from
failing my
degree. :(
Regards,
Tan Yi Yong
The University of Sheffield
E: mea05yyt_at_sheffield.ac.uk
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