Can I customize the particle orientation using Edem API

Saeed Naamnh

Hi 

Can I customize the particle orientation using Edem API ?

 

 

Best 

Richard Wood_20774

Hi,

Depends what you mean. You could use a custom factory to make them start in whatever orientation you like, though you can do similar in a regular factory without the API.

If you mean mid simulation, then yes - kind of - but you can't explicitly set the orientation in the API, you would need to back calculate it from an appropriate force/torque. The same concept, but with velocity, is mentioned in this post:

https://community.altair.com/community?id=community_question&sys_id=b219e5811bd59d14507ca6442a4bcb8b&anchor=answer_88763c761b1dd954507ca6442a4bcbad

Cheers,

Richard

 

satri

The random orientation is not truly random. I am trying to generate a bunch of particles and i have kept the orientation random but whenever the meta-particles get generated it is slightly biased in one direction why is ti so? Is there a workaround? can the orientation be set to a truly random number through an API at the beginning when the particle is generated? 

Please see the image below

There is some kind of a bias

why are there very less particles in y direction? i don't have too many constraint for factory generation the dimensions of the factory is 300*300 sq units Which is ample room to have a lot more orientations.

How to get a truly random orientation?

Richard Wood_20774

Shyam Prasad V Atri said:

The random orientation is not truly random. I am trying to generate a bunch of particles and i have kept the orientation random but whenever the meta-particles get generated it is slightly biased in one direction why is ti so? Is there a workaround? can the orientation be set to a truly random number through an API at the beginning when the particle is generated? 

Please see the image below

There is some kind of a bias

why are there very less particles in y direction? i don't have too many constraint for factory generation the dimensions of the factory is 300*300 sq units Which is ample room to have a lot more orientations.

How to get a truly random orientation?

Hi,

I'd say that's not a huge sample size but I get your point - it certainly looks like it has a bias based on that sample. At first glance it doesn't look totally random but I'd maybe leave it running just to double check? Is it the same when looking along X and Y axes as well?

I couldn't tell you our implementation off the top of my head so it would require some investigation on our side.

In the mean time, if you did want to do a more random distribution (you will never get true random in code, without external input of some nature) you could write a custom factory using the API, where you can control the orientation. Alongside that, it's up to you what random number generator you want to use.

Cheers,

Richard

Richard Wood_20774

Shyam Prasad V Atri said:

The random orientation is not truly random. I am trying to generate a bunch of particles and i have kept the orientation random but whenever the meta-particles get generated it is slightly biased in one direction why is ti so? Is there a workaround? can the orientation be set to a truly random number through an API at the beginning when the particle is generated? 

Please see the image below

There is some kind of a bias

why are there very less particles in y direction? i don't have too many constraint for factory generation the dimensions of the factory is 300*300 sq units Which is ample room to have a lot more orientations.

How to get a truly random orientation?

I just did my own meta particle random test and it seems fine to me:



Are you sure there's plenty of room for it to be oriented in all those different orientations? I could see how in a very small volume that there would only be a limited number of orientations possible

satri

Please let me know how to write a custom factory?

I looked for examples in knowledge Base and couldn't find any examples for a API of custom factory to give orientation

satri

Shyam Prasad V Atri said:

Please let me know how to write a custom factory?

I looked for examples in knowledge Base and couldn't find any examples for a API of custom factory to give orientation

Never mind i found it EDEM tutorial 6 is for custom factory. 

I have a question about that API now. suppose i want to use that API to create particles of different orientations and random positions.

If there is any particle already present in that random position I pick how will I make the API skip that position? How can I check for the presence of another particle at that position? is there any inbuilt command for that?Please let me know

I only want to create particles with the API in the initial step only after that i don't want to control its position

 

satri

Also can you create meta particles with this factory? because i get this error

 

Richard Wood_20774

Shyam Prasad V Atri said:

Also can you create meta particles with this factory? because i get this error

 

Hi,

No, currently you can only place 'regular' particles. You can recreate the same behaviour as a meta-particle through a custom factory and bond the particles after creation, but it's a bit of work to do so. This is essentially what meta-particles are though.

Cheers,

Richard