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density variation in rotating fluid

Posted Dec 27, 2010, 5:23 a.m. EST 3 Replies

bluesmoke
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Hi,

Is it possible to model density variation in a rotating fluid?
3 Replies Last Post Dec 27, 2010, 12:16 p.m. EST
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 1 decade ago Dec 27, 2010, 5:47 a.m. EST
Hi

that depeds what you mean by "density" variations. If it's simply to add a centrifugal body load then yes this is rather straight-forward you add a force in a cylindrical reference as

Fr=rho*w^2*R

there is an example in structural doc for a rotating shaft

--
Good luck
Ivar
Hi that depeds what you mean by "density" variations. If it's simply to add a centrifugal body load then yes this is rather straight-forward you add a force in a cylindrical reference as Fr=rho*w^2*R there is an example in structural doc for a rotating shaft -- Good luck Ivar
bluesmoke
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Posted: 1 decade ago Dec 27, 2010, 8:27 a.m. EST
Thanks Ivar,

I could not find the example you referred. Can you please give me more information about that. Moreover how (in which node) I can add the centrifugal body load. If I am using rotating machinery, should I express this under 'volume forces'.
Thanks Ivar, I could not find the example you referred. Can you please give me more information about that. Moreover how (in which node) I can add the centrifugal body load. If I am using rotating machinery, should I express this under 'volume forces'.
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 1 decade ago Dec 27, 2010, 12:16 p.m. EST
Hi

Volume for ce or body force are forces acting on each element of a domain therefore the

F[N/m^3] = solid.rho[kg/m^3]*(w[1/s])^2*r[m]

where w is the rotation speed

--
Good luck
Ivar
Hi Volume for ce or body force are forces acting on each element of a domain therefore the F[N/m^3] = solid.rho[kg/m^3]*(w[1/s])^2*r[m] where w is the rotation speed -- Good luck Ivar

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