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Application of standard rolling friction model to geometry in EDEM.

Hello everyone,

I noticed that it is mentioned in the help document that EDEM ignores the rolling friction calculation of geometry by default, but it can be opened manually. And the distance of the contact point from the center of mass (Ri) is required to calculate the torque of rolling friction. What I want to know is what Ri means for geometry? Or where can I see the relevant code (I didn't find it in the rolling friction API)?

Thank you！

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v2020.2

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RWood

Hi,

I'm not sure what you mean by the rolling friction is ignored by default? The default behaviour for both p-p and p-g is the standard rolling friction model.

The API model for the rolling friction model calculates the torque here:

Does that help?

Richard

Yu Mu

Hi,

I'm not sure what you mean by the rolling friction is ignored by default? The default behaviour for both p-p and p-g is the standard rolling friction model.

The API model for the rolling friction model calculates the torque here:

Does that help?

Richard

Hello Richard,

I saw this paragraph in the help document:

Maybe I misunderstood the meaning of this passage?

Thank you for your answer, but I also want to know what "coP1toConatactDistance" means when calculating the torque of geometry? Does it calculate the distance from the contact point to the center of the mesh where the geometry is divided?

Sincerely,

Yu Mu

Hi,

I'm not sure what you mean by the rolling friction is ignored by default? The default behaviour for both p-p and p-g is the standard rolling friction model.

The API model for the rolling friction model calculates the torque here:

Does that help?

Richard

Hi Richard,

I went to check the code of rolling friction and saw that there was a judgment condition (if statement) when calculating the element2, as shown in the following figure：

My personal understanding is that this if statement needs to determine that the element2 is a sphere before it can run. I don't know if I understand it right? If it is correct, how to calculate the geometry?

Sincerely，

RWood

Hello Richard,

I saw this paragraph in the help document:

Maybe I misunderstood the meaning of this passage?

Thank you for your answer, but I also want to know what "coP1toConatactDistance" means when calculating the torque of geometry? Does it calculate the distance from the contact point to the center of the mesh where the geometry is divided?

Sincerely,

Yu

Hi,

I wasn't aware this was switched off by default actually and that's quite the surprise. I'm trying to find out more on why.

Here, coP1toContactDistance is the distance of the centre of particle to the contact point, where the centre of the particle is taken to be the centre of mass.

As for the contact point, that is not the centre of the mesh element but is the point at which the particle is contacting the mesh element.

Cheers,
Richard

RWood

Hi Richard,

I went to check the code of rolling friction and saw that there was a judgment condition (if statement) when calculating the element2, as shown in the following figure：

My personal understanding is that this if statement needs to determine that the element2 is a sphere before it can run. I don't know if I understand it right? If it is correct, how to calculate the geometry?

Sincerely，

Yu

Hi,

That's correct. As I say, I hadn't been aware this was disabled to the geometry torque by default.

For a bit of background, element1 is always a particle, but element2 can be a particle or a geometry. The way to determine if it's a geometry is with the .isSphere method. So in this case the model always calculates the torque on the particle but not the geometry.

Cheers,
Richard

Yu Mu

Hi,

That's correct. As I say, I hadn't been aware this was disabled to the geometry torque by default.

For a bit of background, element1 is always a particle, but element2 can be a particle or a geometry. The way to determine if it's a geometry is with the .isSphere method. So in this case the model always calculates the torque on the particle but not the geometry.

Cheers,
Richard

Hello Richard,

Thank you for your patience and hope you can find the reason for this problem. If you make progress, I hope you can tell me the answer.

Sincerely,