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Magnetic force imposing on magnetic fluid in 3D magnetostatic field (no currents)
Posted 02.09.2012, 06:09 GMT-4 Low-Frequency Electromagnetics, Fluid & Heat Version 3.5a 6 Replies
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Everyone
I try to do with a simulation of magnetic fluid imposed on magnetic force in magnetostatic field (no
currents), but the results show that there seems to be no magnetic force on magnetic fluid.
Equations of magnetic force are expressed as:
Fx= mu0_emqa*(Mx_emqa*d(Hx_emqa,x)+My_emqa*d(Hx_emqa,y)+Mz_emqa*d(Hx_emqa,z))
Fy= mu0_emqa*(Mx_emqa*d(Hy_emqa,x)+My_emqa*d(Hy_emqa,y)+Mz_emqa*d(Hy_emqa,z))
Fz= mu0_emqa*(Mx_emqa*d(Hz_emqa,x)+My_emqa*d(Hz_emqa,y)+Mz_emqa*d(Hz_emqa,z))
I am sorry that I could find out what went wrong, and your help is highly appreciated!
Thanks!
Best wishes
Hongliang Zhou
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What magnetic force equations you are following?
The equation is:
F=mu0*M*(detaH)
Do you have any suggestions?
I am looking forward to your replies.
Best regards
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did you find the answer? i'm finding exact same one as yours
Thanks for your attention!
I am sorry that I still could not find the answer, and I am wondering if the magnetic force is related to the distribution
of magnetic field intensity and magnetization, foe the reason that the magnetic force is defined from the relation
F=mu0*M*(detaH).
What is more, would you mind giving me some suggestions about the yield stress simulated with COMSOL?
I am looking forward to your replies.
Best regards
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I don't know if this helps, but one thing you should check is the spatial derivatives of the magnetic field H. Is every single one of them zero by itself? This is for example the case, if you are solving in some sort of magnetostatic mode, the governing equations are formulated for a scalar potential phi and the field follows from H = - grad phi. Therefore, all the components in the force expressions are indeed second order derivatives.
An easy work around is to add additional (auxiliary) variables (Hx, Hy, Hz) which are defined as, e.g. Hx = - diff(phi,x). This way, you should be able to evaluate all expressions diff(Hx,x) and so on.
Alex
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Hi,
I don't know if this helps, but one thing you should check is the spatial derivatives of the magnetic field H. Is every single one of them zero by itself? This is for example the case, if you are solving in some sort of magnetostatic mode, the governing equations are formulated for a scalar potential phi and the field follows from H = - grad phi. Therefore, all the components in the force expressions are indeed second order derivatives.
An easy work around is to add additional (auxiliary) variables (Hx, Hy, Hz) which are defined as, e.g. Hx = - diff(phi,x). This way, you should be able to evaluate all expressions diff(Hx,x) and so on.
Alex
Dear Alex,
Thanks fou your suggestions, I will try my best to do it as what you said.
Best wishes,
Hongliang