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mpm vary source property questions

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Message 1 of 6
userX4542
513 Views, 5 Replies

mpm vary source property questions

Hello everyone,

 

I've been playing around with the mpm solver and when loading in an example from the browser, I can't get the vary_source_property to have an effect on the simulation. Even when I enter extreme values. This includes new ones, ones that come with the existing graphs, and ones for different data types such as direction or friction. 

Nothing has been cached and other nodes are working fine in the simulations. Has onyone else experienced this? Am I doing something wrong?

5 REPLIES 5
Message 2 of 6
wongt
in reply to: userX4542

Hello,

Here is a quick test with 'friction' (attached is a scene file and videos comparing default value and vary value).

The values I used in the vary_source_property are:

General>Property - friction

Random Variation>Min - 0

Random Variation>Max - 10

Random Variation>Bias - 0.85 (leaning towards the max value)

NOTES:

-friction in this case is not against he collider but between particles

-the values are set at start frame (so the animated flag can be turned off)

 

It looks like there might be an issue with 'direction'.  I continue to take a look and update when I have some results.

 

Message 3 of 6
wongt
in reply to: wongt

Hello,

After a bit of investigation, it looks like 'direction' is currently not supported.  We have listed the supported properties in the documentation.  

  • source_mpm_sand : "volume_preservation", "viscosity", "vibration_speed", "friction", "cohesion", "initial_speed", "inherit_velocity".
  • source_mpm_snow : "initial_firmness", "hardening", "volume_preservation", "viscosity", "vibration_speed", "friction", "cohesion", "initial_speed", "inherit_velocity".
  • source_mpm_fluid : "surface_tension", "viscoelasticity", "relaxation_time", "viscosity", "vibration_speed", "initial_speed", "inherit_velocity".

I have checked some of these other parameters and have been getting expected results.  Please let us know if you are are seeing something different.

NOTE:  I have logged an issue with reference BIFROST-3462  for added support. 

 

Message 4 of 6
userX4542
in reply to: wongt

Thanks for the reply. I had a look at the scene files and it's very helpful. The friction property is working correctly for me when I change the vary_source_property values. However I'm still having trouble affecting other properties like initial_speed.

 

Is it the case that the vary_source_property should override the corresponding property in the source_mpm_sand? In my graph, the source_mpm_sand value of the initial_speed still seems to take presedence. 

 

vary_source_property_02.JPGvary_source_property_03.JPG

Message 5 of 6
wongt
in reply to: userX4542

Hello,

Yes, the vary_source_property should override the property that is it varying.  Current behavior is that if the min and max values are 0, it will return to the values set on the source node.  After a design review, we have decided to respect all values on the vary_source_property node.

I will investigate the issue with the initial_speed.

Message 6 of 6
wongt
in reply to: wongt

Hello,

I can confirm the issue with initial_speed and have logged something internally (reference: BIFROST-3481)

Thanks for reporting.

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