# Free surface flow modelling using SPH with periodic boundary condition

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February 14, 2018, 21:12
Free surface flow modelling using SPH with periodic boundary condition
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Victoria
Join Date: Feb 2018
Posts: 3
Rep Power: 8
Hi all,
I am trying to simulate a free surface flow over an inclined surface with explicit incompressible SPH and periodic boundary conditions in x-direction. The flow is driven by gravity in x direction (gsin(theta)). But I can't get the analytical solution and the velocity keeps increasing until it converges to a value which is not what I expect (as you can see in the figure). Does any of you have any idea what could cause this problem?
Thanks a lot
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 SPH problem.jpg (52.4 KB, 6 views)

 February 15, 2018, 00:33 #2 Senior Member     Uwe Pilz Join Date: Feb 2017 Location: Leipzig, Germany Posts: 744 Rep Power: 15 I don't know how you set up your case. Inclined and periodical b.c. does not fit. Do you use inclined gravity? Periodic b.c. couples the outlet with the inlet. You have to ensure, that from physics both sides are real equal. If the outlet transforms energy to the inlet, your velocity will increase until blowup. hosseinbasser likes this. __________________ Uwe Pilz -- Die der Hauptbewegung überlagerte Schwankungsbewegung ist in ihren Einzelheiten so hoffnungslos kompliziert, daß ihre theoretische Berechnung aussichtslos erscheint. (Hermann Schlichting, 1950)

 February 15, 2018, 00:42 #3 New Member   Victoria Join Date: Feb 2018 Posts: 3 Rep Power: 8 Thank you for your response. What I did was I set up a horizontal domain and inserted a body force in horizontal direction to account for the gravity (g*sin(theta)). Best regards

 Tags free surface flow, periodic boundary, sph method

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