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Setting a Velocity profile for a circular boundary

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Old   February 5, 2016, 13:55
Default Setting a Velocity profile for a circular boundary
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Dear all,

Could you recommend the best way to assign a velocity profile to a circular surface? I´m making a wind flow study on a circular domain, but I don´t know how to introduce the velocity boundary condition. How can I just assign a velocity magnitude and direction for this case when the velocity signal must change whit the angle?

Thanks in advance!
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Old   February 5, 2016, 17:07
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What is the geometry of the domain and what velocity profile would you like to implement? You can either specify a velocity boundary condition in the normal direction of each cell face or specify the velocity in each direction (x, y, z).
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Old   February 8, 2016, 08:47
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A cylinder delimits a portion of a hilly terrain where the wind blows with a heading of 120 degrees west of north. The velocity value could be positive or negative if the vector is entering or leaving the domain, respectively.

Thanks 'e'!
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Old   February 8, 2016, 23:21
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Break the vector up into components (x and y; as well as z in 3-D). For example, your 120 degrees west of north unit vector would be:

\cos(\dfrac{4}{3}\pi){\boldsymbol{\hat{\textbf{\i}}}} + \sin(\dfrac{4}{3}\pi){\boldsymbol{\hat{\textbf{\j}}}} = -\dfrac{1}{2}{\boldsymbol{\hat{\textbf{\i}}}} - \dfrac{\sqrt{3}}{2}{\boldsymbol{\hat{\textbf{\j}}}}

Under Define > Boundary Conditions... select the velocity inlet condition and use "Components" for the "Velocity Specification Method". Enter the unit vector (above) multiplied by your wind speed.
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Old   February 11, 2016, 08:22
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Quote:
Originally Posted by `e` View Post
Break the vector up into components (x and y; as well as z in 3-D). For example, your 120 degrees west of north unit vector would be:

\cos(\dfrac{4}{3}\pi){\boldsymbol{\hat{\textbf{\i}}}} + \sin(\dfrac{4}{3}\pi){\boldsymbol{\hat{\textbf{\j}}}} = -\dfrac{1}{2}{\boldsymbol{\hat{\textbf{\i}}}} - \dfrac{\sqrt{3}}{2}{\boldsymbol{\hat{\textbf{\j}}}}

Under Define > Boundary Conditions... select the velocity inlet condition and use "Components" for the "Velocity Specification Method". Enter the unit vector (above) multiplied by your wind speed.

Thanks again 'e',
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