Software Simulation of Magnetic Viscosity

[gravityblock]

According to Sean McCarthy in 2007, they use an FEA package called Flux3D from Cedrat ( http://www.cedrat.com ). Sean says, "I should point out that the system does require some code changes in order to demonstrate the effect which is based around Magnetic Viscosity", http://peswiki.com/index.php/Steorn#Software_Modeling

The purpose of this thread is to use Flux3D or other simulation software in order to simulate the effect of magnetic viscosity with the main focus on the needed code changes to demonstrate this effect.  After we know what the needed code changes are, then we can have a discussion on the simulation results.

Flux3D, http://www.cedrat.com/en/software-solutions/flux.html

Flux is suitable for designing, analyzing and optimizing a variety of devices and applications such as :  Rotating machines, Linear actuators, Electromagnetic compatibility, Transformers, Induction heating devices, Sensors - HV devices, Cables, Nondestructive Evaluation

I think this would be an exciting project.

GB

[gravityblock]

Flux 3D is a finite element software (FEA) application and isn't open sourced, so it may not be the best choice in order to have the greatest amount of participation with this project.  There is however, alot of good documents on Cedrat. 

FEMM, http://www.femm.info/wiki/HomePage is also an FEA software, is open-sourced, and is well known to most users here.  FEMM may be a good choice, but I would like to know if it's the best choice for this purpose by reviewing the list of simulation software on wiki.  Here is a list of Finite Element Software packages found on wiki, http://en.wikipedia.org/wiki/List_of_finite_element_software_packages

Thanks,

GB

[gmeast]

Flux 3D is a finite element software (FEA) application and isn't open sourced, so it may not be the best choice in order to have the greatest amount of participation with this project.  There is however, alot of good documents on Cedrat. 

FEMM, http://www.femm.info/wiki/HomePage is also an FEA software, is open-sourced, and is well known to most users here.  FEMM may be a good ---
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Thanks,

GB

@ thread,

Magnetic viscosity has been observed and characterized countless times.

Changing simulation software can end up being a monumental task and may only serve to raise suspicion
as to motive ... not from me, but why give anyone the ammunition?

How about a table tabulated from data points acquired from a test rig built to specifically characterize magnetic viscosity in an Orbo motor configuration?  Then you use that data to "correct" the results of the simulation.

I personally don't like doing this since this is what the climate folks recently did that resulted in "ClimateGate".  Their "correction" was actually a 'biasing' of the data to keep their grants rolling in.

Quoting and crediting the following from the link:
http://prola.aps.org/abstract/PR/v54/i4/p288_1
(Look at the date.  I'm sure there are earlier references)

My 2 cents,

Greg
-----------------------------------------------------
C. W. Heaps
The Rice Institute, Houston, Texas

Received 20 June 1938

Magnetic viscosityâ€"the change of induction occurring after the magnetizing field has ceased to varyâ€"has been measured in a bar of commercial iron, with a measuring circuit designed to eliminate spurious effects arising from sparking at switches. Magnetic viscosity is found to depend on previous magnetic states, in agreement with observations of Mitkevitch and contrary to Preisach's results. It appears, therefore, as if reversible domains could retain their lagging propensity while the magnetic force is varying over a considerable range. The viscous effect is found to depend on the magnitude of the previous change of induction if the latter is small, but is independent of this change if it is greater than 60 gauss. In small, subsidiary hysteresis loops, such as are used in determining reversible permeability, it is found that the Barkhausen effect is not present although there is hysteresis and magnetic viscosity. It is therefore concluded that the movement of the boundaries of saturated domains in the material is subject to time-lag.

© 1938 The American Physical Society
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[gravityblock]

@ thread,

Changing simulation software can end up being a monumental task and may only serve to raise suspicion
as to motive ... not from me, but why give anyone the ammunition?

How about a table tabulated from data points acquired from a test rig built to specifically characterize magnetic viscosity in an Orbo motor configuration?  Then you use that data to "correct" the results of the simulation.

I personally don't like doing this since this is what the climate folks recently did that resulted in "ClimateGate".  Their "correction" was actually a 'biasing' of the data to keep their grants rolling in.

Quoting and crediting the following from the link:
http://prola.aps.org/abstract/PR/v54/i4/p288_1
(Look at the date.  I'm sure there are earlier references)

My 2 cents,

Greg
-----------------------------------------------------
C. W. Heaps
The Rice Institute, Houston, Texas

Thanks for your input and your concerns are valid.  If FEMM could simulate the magnetic viscosity, then it would help us to determine the best core materials and properties.  From the little research I have done so far, I don't think it's much more than a few equations based around the B-H hysteresis loop.  Here's an article on computer software simulation of magnetic viscosity with a few equations, http://www.overunity.com/index.php?action=downloads;sa=downfile&id=376

If FEMM isn't programmed to take this effect into account, then I don't see anything wrong with making a few code changes in order to simulate an effect.  This is probably more common than you think. This is what Steorn has done with Flux3D and probably for a good reason.

I think a table tabulated from data points acquired from a test rig built to specifically characterize magnetic viscosity in an Orbo motor configuration is a good idea also.  I have an article from the late 1800's on magnetic viscosity by E. Rutherford, http://www.overunity.com/index.php?action=downloads;sa=downfile&id=375  This research was undertaken to see if steel or soft iron exhibited any appreciable magnetic viscosity when under the influence of very rapidly changing fields.  It describes a special form of apparatus for measuring short intervals.  It also says soft iron and steel exhibit the effect of magnetic viscosity quite strongly for a frequency of 1,000 (This could be very important).

GB

[ken_nyus]

Have you guys seen the Steorn patent for a test rig?

http://www.google.com/patents?id=1dOyAAAAEBAJ&zoom=4&pg=PA1#v=onepage&q=&f=true