Dear Mark,



    As I understand the saline is transparent to the magnetic field. That is you can put the ferromagnetic body in saline and place permanent magnet somewhere. The attraction force will be the same as in the air.

    The same is true for the alternating current at _low_ frequencies. High frequency alternating magnetic field could induce eddy currents in saline and cause saline heating (like in a microwave oven). But I doubt that the coils will be operating at such high frequencies.




    The particle motion simulation stays apart from electromagnetic simulation. The nature of the applied force is not important (it could be permanent magnet attraction force, gravity force, acceleration force,...) Modeling the motion in the air is simple - we can neglect the air resistance. Modeling in liquid requires to take into account liquid viscosity.
    QuickField has no facilities to simulate fluid dynamics problem. But taking into account that particle motion is slow the problem could be simulated analytically.
https://en.wikipedia.org/wiki/Drag_(physics)

    Yes, we can compute the particle dynamics. The particle would accelerate till the magnetic force prevails over the drag force. After the forces become equal the motion will continue with constant speed.
    For example, I take the result calculated on November 8. The magnetic force at x=0 is 18.46 times the weight of the particle. That is  8.4e-16 N for a 100 nm iron particle. Then maximal particle speed would be 2.7 cm/s. At higher speed the drag force will prevail over the magnetic force.
    If the particle is free to move all the distance towards the coil then we should take into account the changing magnetic force and compute speed for each particle position. I believe the space is limited by the blood vessels so we can consider the magnetic force to be uniformly distributed.
    The particle will not reach the maximum speed instantly and it is possible to compute the particle dynamics too (speed and distance as a function of time). Please let me know if I should do this.
    
    
    Time spent: 1.5 hours.


       

Best regards,
        Alex

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






On 26.12.2018 18:41, Mark Arokiaraj wrote:
> Dear Alex,
>
>             Is it possible to evaluate the displacement of a magnetic nanoparticle in static saline, with the effect of magnetic field. We will test with 7 x 7T coils (with 3 Central Hallbach), which we got good results. We can use A/C current.
>
> with regards,
> Mark