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June 20, 2020, 04:20 |
Modelling a piston by inlet
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#1 |
New Member
Suk Tan
Join Date: Nov 2019
Posts: 19
Rep Power: 6 |
Can I simply use an inlet to model the flow generated by a piston? A circular piston is located somewhere on a face of a rectangular box. It vibrates back and forth in sinusoidal manner. I want to simulate the flow in the box.
Thanks. |
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June 20, 2020, 04:31 |
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#2 | |
Senior Member
Filippo Maria Denaro
Join Date: Jul 2010
Posts: 6,833
Rep Power: 73 |
Quote:
If the movement of the piston in the is small, you could use a sinusoidal normal velocity compontent on the boundary. This is like a synthetic jet condition see https://en.wikipedia.org/wiki/Synthetic_jet But if the movement is large that can be quite approximate |
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June 20, 2020, 21:01 |
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#3 |
New Member
Suk Tan
Join Date: Nov 2019
Posts: 19
Rep Power: 6 |
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June 21, 2020, 03:02 |
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#4 |
Senior Member
Filippo Maria Denaro
Join Date: Jul 2010
Posts: 6,833
Rep Power: 73 |
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June 21, 2020, 21:19 |
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#5 |
New Member
Suk Tan
Join Date: Nov 2019
Posts: 19
Rep Power: 6 |
Thanks again Filippo. Is selection of BC type: velocity, pressure and mass flow matter? Which can do a better job to simulate the flow generated by the piston?
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June 22, 2020, 04:09 |
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#6 | |
Senior Member
Filippo Maria Denaro
Join Date: Jul 2010
Posts: 6,833
Rep Power: 73 |
Quote:
I suppose that the piston does not allow a net mass to enter, you could prescribe e normal velocity on the boundary, a the whole period it is inflow and outflow so that the total mass vanishes. |
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June 22, 2020, 04:35 |
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#7 |
New Member
Suk Tan
Join Date: Nov 2019
Posts: 19
Rep Power: 6 |
From the text book, an outlet is necessary for any case with an inlet (potential mass source). If the rectangular box is essentially sealed and there is only an inlet, will I encounter numerical problem? It is said the mass is not conserved.
At the moment, air (fluid) within the box is incompressible. |
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June 22, 2020, 04:45 |
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#8 | |
Senior Member
Filippo Maria Denaro
Join Date: Jul 2010
Posts: 6,833
Rep Power: 73 |
Quote:
I was thinking your problem was modelled by a compressible flow. |
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June 22, 2020, 04:56 |
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#9 |
New Member
Suk Tan
Join Date: Nov 2019
Posts: 19
Rep Power: 6 |
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