wind / pressure inside a volume?

with blender's simulation system, is it possible to simulate s.th. like an airdancer, a party horn, or the blowing up of a balloon?

is there a way to create a force field that – when placed inside an object's volume – creates air pressure / flow and only acts on the surrounding mesh? (as opposed to the wind force field, which works globally, which is why it does not matter what its actual location is.)

• Blender has several types Force Field types of objects in the add menu, I'm sure one of those will cover these use cases – Duarte Farrajota Ramos Jun 11 '17 at 22:27
• What a neat idea. I like the advertising man with the floppy arms. – SDsolar Jun 12 '17 at 2:38
• Can you use soft body physics for this? Rather than simulating blowing air in and it expanding, you could vary the soft body settings to cause it to collapse/"inflate" back to its original shape. I'm not very familiar with soft body - I'll play around with it and see if this is feasible. – Rich Sedman Jun 15 '17 at 16:30

Simulating actual airflow and pressure would require complicated fluid dynamics simulation - but you could simulate the effect using Soft Body physics.

Create you mesh and add Soft Body in the Physics properties.

Select the vertices that you want to tie to a fixed point (eg, the ground) and assign them to a new Vertex Group. This will be used to pin them in place so that the mesh is anchored.

It is then just a matter of adjusting the Soft Body properties to get the desired effect, simulating the lack of air pressure by reducing the Soft Body Edge Spings and applying the pressure/air flow by increasing the Edge Springs.

The Soft Body Goal pins vertices in place - set the Vertex Group to the group created to act as the 'anchor' and increate the Strengths and Stiffness to force them to stay in place (otherwise they'll be allowed to drift from their start points).

Decrease the 'Bending' Soft Body Edges setting to allow the body to collapse and increase it to "inflate". You may need to adjust the other settings to get the desired effect.

To prevent the mesh from collapsing too far, set the Edge and Face collision checkboxes and enable Soft Body Self Collision. You might want to change the Self Collision settings to prevent the mesh folding too far into itself and/or change the Soft Body Solver settings for a more accurate simulation if it's behaving erratically (eg, reduce the Error Limit).