Fatal overflow in linear solver

James113 · June 2, 2012, 04:11

Hi all,
I am trying to solve a two way FSI Problem in CFX (Ansys 13).

First I will explain the CFX problem:
Blood simulator flows in an elastic pipe (latex).
The elastic pipe is deformed by an external pressure acting on the surface
(limitted area). The pressure is a time dependent function -- P0*sin(F0*t).

Now, to my problem:
The CFX is working great on frequencies (F0) varying from 6Hz to 21Hz, but when I am trying to apply a 22Hz pressure, the simulation crashes after 1,500 iterations (nothing is changed except the frequency).

I read a little about this error and I know it's related to unphysical boundary conditions. But the boundary conditions haven't changed.

Thanks in advance,
James

ghorrocks · June 2, 2012, 07:29

No, this error means the linear solver has diverged. See FAQ: http://www.cfd-online.com/Wiki/Ansys...do_about_it.3F

June 2, 2012, 04:11	Fatal overflow in linear solver	#1
James113 New Member James Join Date: Apr 2011 Posts: 13 Rep Power: 15	Hi all, I am trying to solve a two way FSI Problem in CFX (Ansys 13). First I will explain the CFX problem: Blood simulator flows in an elastic pipe (latex). The elastic pipe is deformed by an external pressure acting on the surface (limitted area). The pressure is a time dependent function -- P0sin(F0t). Now, to my problem: The CFX is working great on frequencies (F0) varying from 6Hz to 21Hz, but when I am trying to apply a 22Hz pressure, the simulation crashes after 1,500 iterations (nothing is changed except the frequency). I read a little about this error and I know it's related to unphysical boundary conditions. But the boundary conditions haven't changed. Thanks in advance, James

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June 2, 2012, 07:29		#2
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,854 Rep Power: 144	No, this error means the linear solver has diverged. See FAQ: http://www.cfd-online.com/Wiki/Ansys...do_about_it.3F