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September 6, 2018, 04:18 |
Turbulence Model Solver Fail
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#1 |
Senior Member
Pedro Oliveira
Join Date: Feb 2018
Location: Portugal
Posts: 109
Rep Power: 8 |
My simulation consists of a Multiphase simulation where the heated recepient is cooled by surrounding water flow in a channel.
In the recipient I have water vapour and liquid water with buyoancy, turbulence, Total energy, particle and thermal phase change model. In the cooling water domain I have buyoancy model, Total energy model and when I consider the flow of cooling water laminar the solver runs normally, but when I add the Turbulence model it fails in the first iteration at the 4th coeefficient loop. I have an optimized mesh ( with good skewness and small elements) and small iteration steps time(1*10-5 s). The solver fails when I activate the the turbulence model on the cooling water. What can I do to make the solver work? |
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September 6, 2018, 06:17 |
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#2 |
Senior Member
Gert-Jan
Join Date: Oct 2012
Location: Europe
Posts: 1,928
Rep Power: 28 |
It can be anything. Please share your output files (the laminar case and the crashing turbulent case) so we can take a closer look.
And maybe a picture of your case.......... |
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September 6, 2018, 16:33 |
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#3 |
Senior Member
Pedro Oliveira
Join Date: Feb 2018
Location: Portugal
Posts: 109
Rep Power: 8 |
Here it is the OUT file when crashes
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September 6, 2018, 21:48 |
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#4 |
Super Moderator
Glenn Horrocks
Join Date: Mar 2009
Location: Sydney, Australia
Posts: 17,871
Rep Power: 144 |
__________________
Note: I do not answer CFD questions by PM. CFD questions should be posted on the forum. |
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September 7, 2018, 14:28 |
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#5 |
Senior Member
Join Date: Jun 2009
Posts: 1,880
Rep Power: 33 |
This type of problem is best to build one step at a time.
1- You are using a beta feature not fully tested; therefore, be prepared. 2- Go single phase on both sides first, so the basics are easier and checked out 3- Introduce multiphase with the previous single phase being the dominant phase, or alternatively, remove the interphase interaction (be sure the setup is consistent) and set both a 50% volume fraction. Both phases should behave the same as single phase, then slowly moves towards your goal. |
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September 9, 2018, 09:57 |
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#6 |
Senior Member
Gert-Jan
Join Date: Oct 2012
Location: Europe
Posts: 1,928
Rep Power: 28 |
Pedro,
you are trying so solve a very difficult physical problem. In CFX-Pre, you turn on all physical models, and let the CFX-solver find out for himself, while keeping fingers crossed. That is not how it is going to work. As Opaque mentioned, start as simple as possible (start with plain air through your system) and if the results are fine, increase complexity. Do it step by step. Some specific help - show me your dimensional analysis where you prove gravity is an important phenomena to include. - Why do you run transient? Why not steady state? - if you want to run transient, then why not use your 'converged' laminar solution as an initial guess? - you have an inlet and an outlet, both with massflow sepcified 2.2kg/s. Why don't you use a pressure boundary? That is much more logical. |
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