Emitter reaction (Newtons 2nd Law) after emission?

[Anonymous]

Hi Humans.

Any guide in how to make an emiter react from its fluid emission acording  2nd Newtons Law ?

Best Regards ...

-- Sergio

[syracoj]

what is the 'implied' force (excluding gravity)? nParts just spit out of a point in space (when gravity is off). There is no force motivating them like you would find in a collision reaction with RBD. So I would guess you would need an implied force.

where 

F=ma

and F is Kg(m/s^2)

you would need 

impliedForce/m = a

or

impliedForceAttribute / (getAttr nParticleShape1.pointMass) = a

so you would kill the speed attr on the emitter node

and then input the equation into the per particle array attribute for Acceleration as an expression.

(if you test this out though, remember to disable the nucleus gravity while you tweak it to get the result you need, and then turn the grav back on when you have your look/solution)

this may work. 

I'll ask duncan, because I may be wrong about implied force. Maybe the system models a generic 'default' force built in (when grav is off).

[syracoj]

I did a quick test with a directional emitter.

turned gravity and wind off (ignore solver grav and wind checked on)

set the speed on the emitter node to 0

Force is a vector quantity

but Maya nPart shape has a localForce attribute. 

I tried an expression on the PerParticle (Array) Attributes Acceleration but discovered that the expression applies the acceleration in all cartesian directions (its not constrained to any particular direction) It shoots off, up, and out in X,Y,Z.

So an expression may need to be made from the localForce attributes (but this is going to depend on what you want to do)

expression tried on the Accelerator perPart attr

float $aForce = `getAttr "nParticleShape1.localForceX"`;
float $getMass = `getAttr nParticleShape1.pointMass`;
nParticleShape1.acceleration = ($aForce/$getMass);

is this operating in Newtons? Not sure. Will ask about this also.

[syracoj]

re-readin your original question...

did you mean to ask if there was any way to make an emitter react to newtons 3rd law? Every action is an opposite and equal reaction?

also, in my previous post, perhaps the syntax I need to deal with the vector requirements of the accel is this:

acceleration = acceleration + << int/float, int/float, int/float >> 

so...

// float $aForce = 10;
float $aForce = `getAttr "nParticleShape1.localForceX"`;
float $getMass = `getAttr nParticleShape1.pointMass`;
nParticleShape1.acceleration = nParticleShape1.acceleration + << ($aForce/$getMass), 0, 0 >>;

[syracoj]

hey Sergio,

taking a second look at this...

you were inquiring to this in regards to fluids (such as maya classic fluids) specifically?

If so, I apologize for the nParticle example

could you explain some more what you are trying to do?

tnx.

[Anonymous]

= =
Hi Syracoj,
thanks for the idea.

Your nPart helpped me alot.
The case that I m talking is basically the fololwoing model-problem:

Consider a ball , falling in the moon surface and emiting a particle-jet.
The challenge is: how desacelerate ( or acelerate ) the ball due the
jet-flow and the reaction ?

It also should work if we apply the jet if the ball is on the moon surface.

Here is a link for the primitive prototipation ...

https://www.youtube.com/watch?v=2tdNa6WwvgE

BTW, this is for the Google Lunar XPrize SpaceMETA Open Source Project...

Best,

--
-- *Sergio* Cabral Cavalcanti
www.IdeaValley.com.b r
,
& www.SpaceMETA.com.br
--


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