Dear Mark,

    It is possible to adjust the scale so that the flux density distribution in some regions is visualized with high contrast.
    For once - in the point located 10 cm away from the coil the flux density is about 0.8 T, The flux density at the coil surface is 5 T. So I set the scale limits from -2 to 5 T. That eventually puts some regions out of scale (coil internals with flux density above +5T and the violet areas with flux density below -2 T).
    Please see 5_coils_setup.gif picture.


    Now I have studied the flux density distribution in the violet zone (violet_part.gif). Again I adjusted the scale to see better the field distribution within the violet zone (violet_scale.gif).

    The general rule is that the ferromagnetic particle is pulled toward the zones with higher magnetic field intensity. There is a crest where the filed gradient is zero and so is the force. For other regions it is difficult to calculate gradient, as the vector field changes in value and in direction.

    So I performed the simulation with test particle of 1 mm-diameter. The exact location is dX=1 cm, dY=1cm away from the coil top-left corner.
    The force calculated is 0.19 N and points right-bottom (force_1mm.gif). Next I simulated the case with 0.1 mm-particle. The force is 0.19e-3. From previous experiments (Aug 23) we know that the force is proportional to the particle's volume. Here we find the agreement with that statement - 0.1 mm particle volume is 1000 times smaller than that of the 1-mm particle and so is the force.

    We can deduce that the force acting on the 100-nm particle would be 0.19e-12 N. That is 4100 times the particle weight.
    In the usual point of interest, located on the coil axis 10 cm-away from the coil, the force is only 395 times the particle weight (please see the pdf file attached).

    
    Time spent 2 hours.
    


Best regards,
    Alex

-------------------------------------
Aleksandr Liubimtcev
QuickField Support team
http://quickfield.com
e-mail: aleksandr.liubimtcev@quickfield.com





On 16.10.2018 18:15, Mark Arokiaraj wrote:
> Dear Alex,
>            If you any good results of the violet area you can send me.
> The violet area has some advantages though the force is negative. The
> force can be generated with few coils...
> with regards,
> Mark