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Old   August 4, 2011, 12:22
Default Pressure far field
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Hi,

I am trying to resolve the flow around an aerofoil. I want to use the pressurefarfield boundary condition around my aerofoil instead of walls, velocity inlet and pressure outlet. Is this possible?? I tried to run the simulation but id does no converge! Can anyone explain how do you set up the pressurefarfield boundary condition? I am running in 2D and my boundary conditions are:

Pressurefafield (around aerofoil)

Wall (aerofoil)

Fronandback empty.

Thank you in advance,

A.D.E.

PS: I am running incompressible flows v=80m/s.
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Old   August 9, 2011, 04:44
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Old   August 9, 2011, 09:08
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Hello A.D.E
Can you explain what is far field boundary condition ?
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Old   August 9, 2011, 12:23
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Hi,

Thank you for your interest. I used Fluent before and at compressible flows it recommends the use of Pressure far field boundary conditions:

The definition in the fluent manual is:

Pressure far-field conditions are used to model a free-stream condition at infinity, with free-stream Mach number and static conditions being specified. The pressure far-field boundary condition is often called a characteristic boundary condition, since it uses characteristic information (Riemann invariants) to determine the flow variables at the boundaries.

I donít know if something similar exist in OpenFOAM since I just started using the software.

Thank you in advance for your consideration and time,

Sincerely,

A.D.E
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Old   August 10, 2011, 03:31
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A.D.E,
Far field and near filed are two approaches in CFD to calculate drag.

i.e. both these approach would give same drag force

If you use far field you need to calculate "induced drag" + "wave drag" + "vortex drag"
If you are using Near field approch you need to calculate "pressure drag"+"friction drag".

Which ever approach one uses be sure sum of all components will be equal for both approach.

Cheers
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