Outlet Fluid Speed

James · August 2019

When simulating inlet/outlet cases, it is quite common that the inlet fluid speed is known but outlet fluid speed is unknown. Is that possible to solve this kind of problems in DSPH? What is the correct configation of xml files for this kind problem?

Asalih3d · August 2019

I advise you to look through some of the examples for "inlet/outlet". What you request is possible, you have to use setting "2" and has been showcased in the examples, see for example "CurrentHull".

Kind regards

cube · January 2020

https://forums.dual.sphysics.org/discussion/comment/3213#Comment_3213

do you mean that if the velocity is unknown, I should set the velocity mode as extrapolated velocity?

I am simulating a pressure flow. the inlet velocity is known, and the outlet is a free outflow with the velocity and free surface unknown. so how to set the velocity, rhop and zsurf at the inlet/outlet respectively.

if I don't add the outlet buffer zone and just let the particles run out of the calculation domain, would it affect the calculation, like the calculation speed and accuracy?

kind regards

Asalih3d · January 2020

Normally one would specify an inlet velocity and a outlet pressure, and then the CFD simulation will figure out what the inlet pressure has to be to accomodate this inlet velocity and outlet pressure. I have never heard as such one specifying only velocities, since pressure differences is what drives the flow. It is in some software though possible to have inlet velocity, outlet pressure and then also velocity constraint on outlet - don't know if DualSPHysics allows for this.

Hope it helps a bit

Kind regards

cube · January 2020

thanks very much @Asalih3d ！

you mean that I should specify inlet velocity and outlet free surface to simulate a pressure flow

kind regards

Asalih3d · January 2020

My advice is to try some different options out and see how things go :-)

CFD is pretty tough, the best way is simply to keep on trying and noting what one does etc.

Kind regards

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Outlet Fluid Speed

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