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+--- Thread: Help Can I measure the fluid pressure? (/thread-3556.html)
Can I measure the fluid pressure? - Bertalicious - 15-08-2022
I haven't purchased Obi Fluid yet, as I'd like to know if it's possible to measure the amount of fluids' pressure on some objects.
For instance, if I had a balloon, and started filling it up with fluid, the balloon should expand as the liquid is being added and, at some point, pop. Let's assume I'd like to measure the amount of pressure the fluid acts on the balloon's "wall" because I'd like to determine where it should pop. The balloon could be of a generated shape, so the popping point might change depending on its structure. Or perhaps the balloon could be created using different-resistance materials, making the pressure distribution different. Would be great to be able to simulate situations like this one.
So the question is - could I do that with Obi Fluid? Furthermore, could I use Obi Softobdy in combination with Obi Fluid to achieve a balloon that reacts to that pressure as a soft body? For example, it slightly stretches if I rapidly inject fluid in a certain place. My end goal is to have deformable bodies with fluid(s) inside, which can be stretched or squished to create tears on their surfaces (and hence let the fluid(s) out in a rather explosive manner).
Thank you for your time and the great tools you've created.
Edit: Think something like Polybridge which shows which bridge elements are about to break under the vehicle(s) pressure.
RE: Can I measure the fluid pressure? - josemendez - 16-08-2022
(15-08-2022, 02:00 PM)Bertalicious Wrote: I haven't purchased Obi Fluid yet, as I'd like to know if it's possible to measure the amount of fluids' pressure on some objects.
Hi!
Depends on what you mean by "pressure on objects". You can measure the magnitude and direction of the contact impulses between particles and colliders, as well as between particles and other particles. See:
http://obi.virtualmethodstudio.com/manual/6.3/scriptingcollisions.html
Pressure is force per area unit, so you would have to factor in the area somehow to get a pressure value. For particle pairs, you could -very roughly- approximate it as the
average particle radius.
(15-08-2022, 02:00 PM)Bertalicious Wrote: For instance, if I had a balloon, and started filling it up with fluid,
Ok, fhere's the first problem: how would you simulate the balloon? If you want it to be a deformable ballon, you would have to use cloth physics for this. Collision detection between a particle-based cloth and fluid would require rather high collision quality settings to avoid tunneling, so chances are the filled-up ballon would be about all you could simulate on screen at once. This may be or may not be a problem for your use case.
(15-08-2022, 02:00 PM)Bertalicious Wrote: the balloon should expand as the liquid is being added and, at some point, pop.
Using tearable cloth all of this would happen automatically.
(15-08-2022, 02:00 PM)Bertalicious Wrote: Let's assume I'd like to measure the amount of pressure the fluid acts on the balloon's "wall" because I'd like to determine where it should pop.
No need to: tearable cloth has a tearing strength threshold. Once its walls stretch past this threshold, the ballon would pop.
(15-08-2022, 02:00 PM)Bertalicious Wrote: The balloon could be of a generated shape, so the popping point might change depending on its structure. Or perhaps the balloon could be created using different-resistance materials, making the pressure distribution different. Would be great to be able to simulate situations like this one.
Obi only supports a single, isotropic material per actor (eg, per cloth, rope or softbody). You cannot have spatially-varying stretch distributions on the surface of a cloth.
(15-08-2022, 02:00 PM)Bertalicious Wrote: So the question is - could I do that with Obi Fluid?
To some extent, yes. The limitations are mainly what I outlined above:
- It's a very expensive scenario to simulate.
- You cannot have spatially-varying materials on cloth.
(15-08-2022, 02:00 PM)Bertalicious Wrote: Furthermore, could I use Obi Softobdy in combination with Obi Fluid to achieve a balloon that reacts to that pressure as a soft body?
Using softbodies in this context doesn't make sense. Ballons are thin membranes with basically zero thickness, cloth is a much better fit for this. Softbodies in general are assumed to have some volume, and their simulation method is optimized for this.
kind regards,