URGENT:fluids emiter question?

[Scob]

Hi all,
i'm looking for a way to emit Fluid from the emitter in the -y axis.


Hi ,

You just need to set the density (and temperature) Buoyancy in a negative value .

Hope it helps ...:rolleyes:

Jerome

[thematt]

thanks Scob but if I set the buoyency to a negative value, the fluids won't go up after the collision happen.It will push down all the time which is not what I want.I need the fluids to maintain a normal behavior dissipating while elevating in the air.that' why i nedthe emitter itself to push the fluids in the direction and not the container.
Sorry if I wasn't clear.

thanks anyway.

cheers

[Scob]

Ah , ok , sorry ...:D

A few weeks ago i found a solution for that on this forum.
I don t remember exactly the thread , but i "know " the process.

I will try to do short and clear :

-You need the have a volumeAxisField in cylinder with a strong magnitude , and with the along axis set to 1 (or -1 ) ( away from axis =0 , alround axis = 0)

- Position your emitter inside the volume axis

- the emission will follow the fields

- animate your volumeAxisField and your emitter in transalte Y

- and enjoy ;)

Hope to be understandable !!:rolleyes:

Jerome

[thematt]

Thanks, yes it's exactly what I did so far, weird enough when I do that it sems that the collision on the surface is not well taken into account..the fluids collide with too much force maybe I don't know, but has trouble going up again, it true that I have to push the fluid very strongly. But yes it works, but not very good.
i find it strange that you can set your emitter to be any volume type you want but have no attribute whatso ever to control the way it emit, seems quite akward to me.

thanks for help though.
cheers

[darktding]

Simply animate the boyancy...
I have said this many times and I will say it again for good measure:
Never use fields for fluid containers to get the motion. Never force the simulaton to do what you want by taking shortcuts and using fields you will crash the simulator and things will not work right. Use fields only for certain cases like a constant wind direction.
Animate the boyancy both temperature and density, and use fuel and reaction speed to seduce the temperature to spread around the base. When you feel it is time to move up then set boyance to a posivite value. Rinse and repeat till you get the desired results; use fields only as the last line of defence.

[thematt]

darktiding, thanks it's intersting, do you mean by setting the fuel is having the temperature of the fluids burn some fuel at collision? How wold you set that up?
Not sure I understand what you want to do but seems intersting.
how would you do then to have the emitter push the fluids downward, and then have the fuel push the fluids upward, seems a bit complicated animated the buoyency since it will affect all the fluids and not simply the position of the emiiter, this mean that once I start animating the buoyency to go up, the emitter itself will emit upward? is there something I'm missing.

Also do any of you render fluids in mental ray, I have big problem with the Alpha of the fluids in mental ray (CustomEntity pass alpha is set to 1), is there a way around that? or do I have to have my color set to 1 over a black Bg to create the alphaChannel, would be too bad to use trick like that though.

cheers

[darktding]

ok I am confused now...
hey matt, can you do me a small favor and please draw/sketch what you are trying to achieve?
It would really help me understand your problem.
Thanks

[thematt]

haha yes of course will do that.In the meantime, just imagine a rocket that would emit some gaz to takeoff, it would emit a lot of fluids, this fluids would collide with the floor and would elevate, but the fluids being emmited from the rocket reactor would continue to emit downward.
Then the rocket would take off and and the fluids around the reactor wold still emit downward while being slow down by the air and push back upward. do you follow me?

Anyway the problem i have is that everything seems fine with the field action (i understand it's bad sorry) but the collision with the floor or bottom of the container is not pushing back my fluids upward, and wit ha buoyency being negative it will definetly not happen.

Thanks a lot.
cheers

[darktding]

thematt, pick up the attachment to see a result I got.

[thematt]

thanks so much..very helpfull.I was actually trying to do it all ,only with density being dynamic, I beleive that's what was making it unable to do correct simulation.
We learn everyday and fluids are a special beast.Now time to go study what's going on in the sim.(So in your scene the temperature is pushing hte fluids down nad the fuel is bring it up after the collision).

anyway thanks a lot own you a big one.
Do you allow me to Pm you if I have trouble getting stuff right with fluids? you seems to know your way pretty good in it.If I can help you in other way just ask.

cheers

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