Learning Forum

[yamamoto]

I want to electromagnetical analize the magnetic field, magnetic flux density, magnetic force about ferrofluid and magnets.
Which ansys soft should I use (or combine which of them)? And, how to analyze the state of the ferrofluid and magnets are put together in near area?

[wrbulat]

 

Hello Kaito,

I am not familiar with the details of using CFX, but perfhaps you might start there. It appears to have the ability to calculate volumetrically distributed magnetic forces:

 

 

I don't know if the ability to define viscosity as a function of magnetic flux density or magnetic force density is a supported feature. If not, perhaps CEL can be used to define this relationship (if it known):

On the other hand, if the analysis you are considering is of a more fundamental nature (say, you want to calculate the increase in effective fluid viscosity as a function of the externally applied B field), you might be able to model a regular arrangement (e.g., body center cubic or face center cubic) of a small number of magnetically permeable nano-scale spheres in Mechanical or MAPDL subjected to an external B field. Presumably the oil in which the spheres are suspended as well as the surfactant that coats them have free space permeability - the spaces between the spheres can be a mesh of free-space permeable magnetic media. If the surfactant is a solid material that coats the spheres, its presence will prevent direct contact of the spheres. Surface to surface contact around each sphere could be assigned a "contact normal offset" (CNOF) to represent the surfactant structure. The elements could be coupled field SOLID226/227 with KEYOPT(1)=10001, giving them the AZ magnetic edge DOF and structural UX, UY, & UZ DOFs. Bidirectional force-displacement interaction is automatic with this element formulation.

The entire assembly could then be subjected to a shear displacement or traction force and its resistance to that mechanical load used to infer an effective fluid viscosity. This approach probably would not work if you wanted to investigate large shear/traction loads that significantly distort the original undeformed sphere arrangement.

I hope this gives you some ideas,

Bill