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October 17, 2012, 05:11
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(U_j+Ug_j)*d(U_i+Ug_i)/dx_j...how to insert properly?
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#1 |
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Member
Tom
Join Date: Jan 2012
Location: France
Posts: 43
Rep Power: 14  |
Hi there,
My question can be seen even from this prospective. I have to insert in the equation this term: (U_j+Ug_j)*d(U_i+Ug_i)/dx_j where Ug_i are the components of a given velocity field and U is the velocity I want to solve. This above is the convective term in the expression "u*grad(u)"-like how can I do? Is it possible? Thank you in advance! Last edited by sawyer86; October 17, 2012 at 13:08. |
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October 17, 2012, 05:23
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#2 |
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Member
Join Date: Mar 2012
Location: Munich, Germany
Posts: 67
Rep Power: 14 |
Hi,
how did you initialise Ug, is it equal to the initialisation of U? Or perhaps there are some problems with the implicit and explicit treatment. You can have a look at this thread: http://www.cfd-online.com/Forums/ope...operation.html. There is a description of the same problem. regards treima |
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October 17, 2012, 05:24
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#3 |
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Senior Member
Anton Kidess
Join Date: May 2009
Location: Germany
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You do not solve for Ug, hence that term is explicit. phi is not the variable you solve for, it's the data from the previous iteration.
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*On twitter @akidTwit *Spend as much time formulating your questions as you expect people to spend on their answer. |
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October 17, 2012, 05:32
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(U_j+Ug_j)*d(U_i+Ug_i)/dx_j
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#4 | |
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Member
Tom
Join Date: Jan 2012
Location: France
Posts: 43
Rep Power: 14 |
Quote:
one question. Do you say that the volume velocity flux is given from the previous iteration...that's so the way how icoFoam treats the non linear-convective term in the way to linearize it, am I right? This linearization influence the calculation of UEqn.H()...but if I do insert that term explict how does UEqn.H() must change? My question can be seen even from this prospective. I have to insert in the equation this term: (U_j+Ug_j)*d(U_i+Ug_i)/dx_j how can I do? Is it possible? Thank you very much |
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October 17, 2012, 05:36
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#5 | |
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Member
Tom
Join Date: Jan 2012
Location: France
Posts: 43
Rep Power: 14 |
Quote:
Sorry I did not explain this term. It is essentially the convective term when you do a kind of linearization starting from a base flow...like in the RANS, but different... Then the term i exactly want to add is the part of the above expression: U_j*dUg_i/dx_j ...? Last edited by sawyer86; October 17, 2012 at 06:24. |
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October 17, 2012, 05:45
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#6 | |
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Member
Tom
Join Date: Jan 2012
Location: France
Posts: 43
Rep Power: 14 |
Quote:
Regards |
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