protected void applyVelocityVariation(Particle particle) {
        particle.velocity.set(initialVelocity);
        temp.set(FastMath.nextRandomFloat(), FastMath.nextRandomFloat(), FastMath.nextRandomFloat());
        temp.multLocal(2f);
        temp.subtractLocal(1f, 1f, 1f);
        temp.multLocal(initialVelocity.length());
        particle.velocity.interpolateLocal(temp, velocityVariation);
    }
This method applies the variation to the particle with already set velocity.
@param particle
       the particle to be affected
jme3-core/src/main/java/com/jme3/effect/influencers/DefaultParticleInfluencer.java