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#1 |
New Member
Amadeo Moran
Join Date: Jan 2012
Location: Madrid
Posts: 10
Rep Power: 14 ![]() |
Dear community,
I was trying to perform a simulation of an actuator disk and reviewing the source code C++ in "actuationDiskSourceTemplates.C" there is a line with the calculation of T (total thrust). Code:
scalar T = 2.0*upRho*diskArea_*mag(upU)*a*(1 - a); Code:
scalar T = 2.0*upRho*diskArea_*sqr(mag(upU))*a*(1 - a); Thanks and regards from Spain! amg. Last edited by a.morang; July 9, 2018 at 04:06. |
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#2 |
Senior Member
Michael Alletto
Join Date: Jun 2018
Location: Bremen
Posts: 616
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I think this is correct since mag calculates the magnitude and not the magnitude squared
see, e.g. http://foam.sourceforge.net/docs/Gui...mmersGuide.pdf |
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#3 | |
New Member
Amadeo Moran
Join Date: Jan 2012
Location: Madrid
Posts: 10
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Quote:
Code:
sqr(mag(U)) == mag(U)*mag(U) Code:
mag(U) = Ux^2 + Uy^2 + Uz^2 |
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#4 |
Senior Member
Michael Alletto
Join Date: Jun 2018
Location: Bremen
Posts: 616
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The units are correct since the complete calculation of the force is:
scalar T = 2.0*upRho*diskArea_*mag(upU)*a*(1 - a); forAll(cells, i){Usource[cells[i]] += ((Vcells[cells[i]]/V())*T*E) & upU;} |
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#5 |
New Member
Amadeo Moran
Join Date: Jan 2012
Location: Madrid
Posts: 10
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#6 |
Senior Member
Michael Alletto
Join Date: Jun 2018
Location: Bremen
Posts: 616
Rep Power: 16 ![]() |
yes. The dot product of two vectors is equal to the magnitude squared:
u & u = ux*ux + uy*uy + uz*uz |
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#7 |
New Member
Amadeo Moran
Join Date: Jan 2012
Location: Madrid
Posts: 10
Rep Power: 14 ![]() |
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actuationdisksource |
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