Particle Orientation matrix

Hi,

Internally everything is done using quaternions but the user should only see the 3x3 rotation matrix representation. It's pretty trivial to convert between the two, should you need to.

https://en.m.wikipedia.org/wiki/Quaternions_and_spatial_rotation

Richard

Thanks Richard 

Hi 

Do you know why the matrix is not symmetric ? 

And why the some of the diagonal values are minus (-)

Hi 

 

Do you know why the matrix is not symmetric ? 

And why the some of the diagonal values are minus (-)

Replied in your other post

https://community.altair.com/community?id=community_Question&sys_id=35270f5a1b8955d0507ca6442a4bcbf3

Hi 

 

Do you know why the matrix is not symmetric ? 

And why the some of the diagonal values are minus (-)

Hi,

With regard to the -ve values this is a useful link for visualising the different orientations:

http://www.euclideanspace.com/maths/algebra/matrix/transforms/examples/index.htm

This would be the matrix to rotate a particle from the position in the Creator at 45degrees in Y axis for example:

If I do 10 degrees in X, 20 in Y and 30 in Z we get:

I use the attached spreadsheet to help with regard to helping understand the different orientations.

Hi Stephen

Thank you for the clarification, But how can I determine the angle value from edem ? 

Hi Stephen,

I want to predicate the intra-particle coating uniformity as a function of the particle's orientation as they pass through the spray zone, and am simulating a spherical shape. From the orientation matrix, how can I determine which vector is the direction of the particle's face?

particle 1

type: Urea
velocity: x = 0.621758 m/s, y = -0.263098 m/s, z = -0.00719657 m/s
position: x = -100.179 mm, y = -99.7823 mm, z = 26.0024 mm
angular velocity: x = 76.4974 rad/s, y = -38.4065 rad/s, z = 46.7943 rad/s
force: x = -1.22761e-05 N, y = -7.95452e-05 N, z = 0.000232114 N
total force: 0.000245672 N
compressive force: 0.000225682 N
torque: x = 5.3362e-07 Nm, y = -2.50706e-07 Nm, z = 4.16641e-07 Nm
mass: 4.46103e-05 kg
residence time: 60 s

orientation

x: x = -0.490355, y = -0.448063, z = -0.747524
y: x = 0.753977, y = 0.212096, z = -0.621718
z: x = 0.437116, y = -0.868478, z = 0.233827

Custom Properties

Liquid Volume: 9.38404e-11 m³
Custom Residence Time: 0.768615 s

Hi,

With regard to the -ve values this is a useful link for visualising the different orientations:

 

http://www.euclideanspace.com/maths/algebra/matrix/transforms/examples/index.htm

 

This would be the matrix to rotate a particle from the position in the Creator at 45degrees in Y axis for example:

 

If I do 10 degrees in X, 20 in Y and 30 in Z we get:

I use the attached spreadsheet to help with regard to helping understand the different orientations.

 

 

Hi Stephen,

I am trying to create a cubic particle which has a fixed orientation. The cube should be rotated 45 degrees about the y-axis, so I used the orientation matrix you presented above. However, EDEM then gives the following message: 

Why is this a problem?

Hi Stephen,

I am trying to create a cubic particle which has a fixed orientation. The cube should be rotated 45 degrees about the y-axis, so I used the orientation matrix you presented above. However, EDEM then gives the following message: 

Why is this a problem?

Hi Raisa,

Do the particles still get created?  This is a warning typically generated due to the accuracy of the inputs but can still allow the particle to be created.

You could try adding the values at a different precision to check if this is accepted by the matrix.  Just to note this error checking has been improved in EDEM 2022.3, it allows inputs to greater accuracy and only checks if it's orthogonal to 3 decimal places. 

2022.3 should be released this week so it maybe best to check with that version once uploaded to the community site.

Regards

Stephen

Hi Raisa,

 

Do the particles still get created?  This is a warning typically generated due to the accuracy of the inputs but can still allow the particle to be created.

You could try adding the values at a different precision to check if this is accepted by the matrix.  Just to note this error checking has been improved in EDEM 2022.3, it allows inputs to greater accuracy and only checks if it's orthogonal to 3 decimal places. 

2022.3 should be released this week so it maybe best to check with that version once uploaded to the community site.

Regards

Stephen

 

Thanks for your reply Stephen! Unfortunately EDEM 2022.2 does not allow me to increase the accuracy beyond 3 decimal places. I will try this in version 2022.3!