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Mantaflow: Effect of forces increases over time.
Confirmed, NormalPublicBUG


System Information
Operating system: Windows 10
Graphics card: Nvidia GeForce GTX 650 Ti
Processor: Intel® Core™ i7-3770

Blender Version
Broken: 2.82, master. (this is a general problem with Mantaflow; previous versions of Blender with Mantaflow implementation also possess this problem)
Worked: (previous gas simulation framework)

Short description of error
The effects of external forces on smoke (vorticity, force-fields, etc.) seem to increase in strength over time, despite not being animated. I am not sure if this is intended behavior; however, it certainly hinders the use of Mantaflow and I believe it should be minimized.

Demo with vorticity. (I am using a very medium strength for vorticity. This problem becomes much more dramatic, when using greater values, such as 1.0)

Demo with a "Force" force-field.

Exact steps for others to reproduce the error

  1. Add a mesh.
  2. Press F3, type in and select "Quick Smoke"
  3. In domain settings, set vorticity to a medium value (ie: 0.3; 0.5; etc.)
  4. Bake the simulation.

Here are two .blend files, one with just the vorticity changes and one with a force field:

Event Timeline

Evan Wilson (EAW) changed the task status from Needs Triage to Confirmed.Feb 15 2020, 4:24 PM

Confirmed using 2.82 release

Bastien Montagne (mont29) changed the subtype of this task from "Report" to "Bug".