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VERY SIMPLE question from people works on unsteady flow |
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December 6, 2011, 11:44 |
VERY SIMPLE question from people works on unsteady flow
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#1 |
Member
Amin Shariat KHah
Join Date: Apr 2011
Location: Shiraz
Posts: 86
Rep Power: 15 |
I want simulate flow between two plate, transient flow which starts to flow from rest according to constant pressure gradient.
I use Finite-Diffrence-Method and fractional step scheme with a staggered mesh. which boundary condition I should use for inlet velocity? |
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December 6, 2011, 17:11 |
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#2 |
Member
Amin Shariat KHah
Join Date: Apr 2011
Location: Shiraz
Posts: 86
Rep Power: 15 |
Anybody know about "the Womersley boundary conditions" ?
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December 6, 2011, 17:58 |
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#3 |
Member
Amin Shariat KHah
Join Date: Apr 2011
Location: Shiraz
Posts: 86
Rep Power: 15 |
I understood
Womersley is BC which use in blood simulating Anybody can help me what should I do for a starting simulation when I know pressure gradient but does not know velocity inlet? |
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December 7, 2011, 06:19 |
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#4 |
Senior Member
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I would use pressure inlet at inlet and pressure outlet at outlet and you will get a flow driven by difference of pressures at the beginning and end of your "pipe" consisting of top and bottom plates. That what people usually do when considering flows in long pipes.
Could you say more about your problem: is it just a simulation of flow between two plates, or they are a part of a bigger system? |
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December 7, 2011, 06:59 |
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#5 |
Member
Amin Shariat KHah
Join Date: Apr 2011
Location: Shiraz
Posts: 86
Rep Power: 15 |
Thanks Dear truffaldino
my problem is that in fractional step on staggered mesh with Finite Difference Method, it need velocity for inlet! Is there any method that need pressure for inlet? Or am I doing any big mistake about problem? |
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December 7, 2011, 19:44 |
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#7 |
Senior Member
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Hello again Amin,
It seems that in order to use pressure BC on inlet/outlet on staggered grids one has to add extra momentum equations on the inlet/outlet cells for velocity components tangential to the inlet/outlet planes. The normal velocities will be fixed by continuity equation. |
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December 8, 2011, 05:13 |
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#8 |
Member
Amin Shariat KHah
Join Date: Apr 2011
Location: Shiraz
Posts: 86
Rep Power: 15 |
Thanks very much
Could you introduce me some references to study more about boundary conditions and transient simulatation? |
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December 9, 2011, 04:58 |
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#9 | |
Senior Member
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Quote:
I am not specialist in this field, but It seems that finite-difference method on staggered grid is not very popular for the kind of the transient channel flow problem you are solving, but anyway it can be used. |
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December 9, 2011, 05:18 |
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#10 |
Member
Amin Shariat KHah
Join Date: Apr 2011
Location: Shiraz
Posts: 86
Rep Power: 15 |
thanks very much dear Truffaldino
I am thinking of changing my method too |
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