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November 17, 2014, 19:16 |
the meaning of "mag"?
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#1 |
New Member
Yongxiao Wang
Join Date: Nov 2014
Posts: 16
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Hello there,
I met some problems about unit. What is the result of the following formula? (2.0)*mag(symm(fvc::grad(U))) Is it the square of strain rate (unit:s^-2) ? What is the meaning of "mag"? |
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November 18, 2014, 02:20 |
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#2 |
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Hrvoje Jasak
Join Date: Mar 2009
Location: London, England
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mag = magnitude
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Hrvoje Jasak Providing commercial FOAM/OpenFOAM and CFD Consulting: http://wikki.co.uk |
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November 18, 2014, 05:46 |
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#3 |
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Yongxiao Wang
Join Date: Nov 2014
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Thank you for your reply.
Dose this means "mag(symm(fvc::grad(U)))" has no unit? But the error information shows the unit of "(2.0)*mag(symm(fvc::grad(U)))*nu()" is "[0 2 -2 0 0 0 0]". Why is it the unit of nu [0 2 -1 0 0 0 0]? |
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November 18, 2014, 07:13 |
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#4 |
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Philipp
Join Date: Jun 2011
Location: Germany
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nu is the kinematic viscosity with unit m^2/s.
U is velocity with unit m/s grad is derivative with unit 1/m Multiply all of them and you get m^2/s * m/s * 1/m = m^2/s^2 Everything is fine.
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