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Old   August 11, 2009, 13:36
Default movingRotatingWallVelocity
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Primoz Ternik
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Hi all,

within OF1.5-dev I am trying to use "movingRotatingWallVelocity" (for Taylor-Couette problem). Here is my set for this type of boundary conditions (for velocity):
.
.
.
WallRotating
{
type movingRotatingWallVelocity;
centre (0 0 0);
axis (0 0 1);
rpm 10;
value uniform (0 0 0);
}
.
.
.

Unfortunately I can not find any reasonable (physical) description for "value"; can anybody , please, explain what is "value"!

Thanks in advance.
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Old   August 11, 2009, 14:23
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Mike Ebert
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I don't have the code in front of me, but I'm pretty sure it is not being used. So you should be able to set it to anything and be ok. Also, beware in earlier revisions of 1.5-dev this BC was missing a 2*pi for converting rpm to rad/sec.
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Old   August 12, 2009, 03:36
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Primoz Ternik
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Quote:
Originally Posted by ebertmp View Post
I don't have the code in front of me, but I'm pretty sure it is not being used. So you should be able to set it to anything and be ok. Also, beware in earlier revisions of 1.5-dev this BC was missing a 2*pi for converting rpm to rad/sec.
Thanks for the answer! Examining the movingRotatingWallVelocityFvPatchVectorField.C file looks like the "value" (by the way it should be set as a vector!) is not used in calculation of rotational speed but it is used for the following:


void Foam::movingRotatingWallVelocityFvPatchVectorField ::write
(
Ostream& os
) const
{
fvPatchVectorField::write(os);
os.writeKeyword("centre") << centre_ << token::END_STATEMENT << nl;
os.writeKeyword("axis") << axis_ << token::END_STATEMENT << endl;
os.writeKeyword("rpm") << rpm_ << token::END_STATEMENT << endl;
writeEntry("value", os);
}

Last but not least, the rotational speed is calculated (I think properly) as:

vectorField Urot =
(axis_ ^ (patch().Cf() - centre_))*rpm_*2*mathematicalConstant::Pi/60;

Cheers,
Primoz.
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