Why P-W force is more than P-P force?

Fatemeh Hosseini_22198

Hello everyone,
I used HM-JKR as the P-P and P-W forces in the CFD-DEM simulation.
I have a horizontal tube with turbulent flow.
When I plotted the P-W and P-P forces I noticed the P-W force was 10 times more than the P-P.
I can't understand why!
There are 550000 particles in a tube. I expected that P-P is higher than P-W.
Could you please guide me in this field?

Regards,
Fatemeh

Stephen Cole

Hi Fatemeh,

 

What measure are you plotting (total, max, average) and which force measure?

 

For flow in a horizontal tube I'd expect all the particles to be moving at approximately the same velocity, in which case the relative velocity in a collision would be low and the force may be low.

Assuming the geometry is stationary this would mean any particle-geometry collisions would have a much higher relative velocity and higher forces?

 

Some images of the system may help, I'd also look at plotting number of p-p and p-g contacts.

 

Regards

Stephen

Fatemeh Hosseini_22198

Stephen Cole_21117 said:

Hi Fatemeh,

 

What measure are you plotting (total, max, average) and which force measure?

 

For flow in a horizontal tube I'd expect all the particles to be moving at approximately the same velocity, in which case the relative velocity in a collision would be low and the force may be low.

Assuming the geometry is stationary this would mean any particle-geometry collisions would have a much higher relative velocity and higher forces?

 

Some images of the system may help, I'd also look at plotting number of p-p and p-g contacts.

 

Regards

Stephen

Many thanks for your answer.
I plot the average force in both P-P and P-W. 
Please see the attached.
I also attached the P-P and P-W numbers of contact.

The first picture is the P-P number of contacts and the second one is P-W number of contacts.

Regards,
Fatemeh

Fatemeh Hosseini_22198

Fatemeh Hosseini_22198 said:

Many thanks for your answer.
I plot the average force in both P-P and P-W. 
Please see the attached.
I also attached the P-P and P-W numbers of contact.

The first picture is the P-P number of contacts and the second one is P-W number of contacts.

Regards,
Fatemeh

I also plotted the average relative velocity in P-P and P-W collisions but the P-P relative velocity is more than P-W.
Please see the attached.

The first picture is P-W relative velocity and the second one is P-P  relative velocity in collision.

Regards,
Fatemeh