Is it possible to define magnet material with sinusoidal Br?

Yes, it is. In Flux (2D and 3D) a magnet material with sinusoidal Br can be defined by using spatial quantity.

The procedure to follow is described below:

1	Create new spatial quantity defined as follow: Name: ex. BR_SPATIAL Type: spatial formula Formula: Cos(FK(Atan2(Y1,X1)-A))B_R*Vec3(Cos(Atan2(Y1,X1)),Sin(Atan2(Y1,X1)),0) The following spatial quantities should be previously created in the project to use them in the formula above: A=0 (it allows setting the phases) FK=360/magnet_segment_presented (ex. 360/180 for ½ cylindrical magnet). B_R is the remanent induction in (T) X1= CLCS(COORDSYS_CARTESIAN,1) Y1= CLCS(COORDSYS_CARTESIAN,2)
2	Create magnet material defined as follow: Name: ex. MAGNET_SINUS Magnetic property: Spatial linear magnet Spatial remanent flux density: BR_SPATIAL
3	Use the created material in the magnet region definition

Create new spatial quantity defined as follow:
Name: ex. BR_SPATIAL
Type: spatial formula
Formula: Cos(FK*(Atan2(Y1,X1)-A))*B_R*Vec3(Cos(Atan2(Y1,X1)),Sin(Atan2(Y1,X1)),0)

The following spatial quantities should be previously created in the project to use them in the formula above:
A=0 (it allows setting the phases)
FK=360/magnet_segment_presented (ex. 360/180 for ½ cylindrical magnet).
B_R is the remanent induction in (T)
X1= CLCS(COORDSYS_CARTESIAN,1)
Y1= CLCS(COORDSYS_CARTESIAN,2)

Create magnet material defined as follow:
Name: ex. MAGNET_SINUS
Magnetic property: Spatial linear magnet
Spatial remanent flux density: BR_SPATIAL

Use the created material in the magnet region definition

To check the result, you can display a 2D curve on a path located in the middle of the magnet region.

Note: The curve should be displayed with respect to cylindrical coordinate system. For instance Comp(1,VLCS(COORDSYS_CYL,Br))