Changing Particle speed over time?

[katherinepyra]

Hello,
I am working on a project that requires me to have particles that increase and decrease their speed over time. I am fairly new to using the particle system in max, and I haven't been able to find any tutorials that have been able to help me with this. The particles need to gain speed over a period of time, and then slow back down. Does anyone have any ideas for how I could go about doing something like this? I am using pf source, I don't wish to download any external plugins(unless they are free for commercial use)

[BenBisares · Accepted solution]

It depends on what you are using to make the particles move. Off the top of my head:

-If you are using the "Speed" operator you can animate the speed value

-Use forces like drag or wind to change their speed

-Use the "Speed Test" operator to take particles over/under a certain speed and then output them to another event where there's another operator that will change the speed

Can you show me an example or give more detail as to what you would like to achieve? I could then try to give you something more specific.

[katherinepyra]

Thanks for the response:)
I can give an explanation of what I am trying to do...I am working on an animation demonstrating how a client's oil filter works. I have a cylindrical containter filling up with oil. There is a float to measure the level of oil in the container,and a pipe that the oil travels out of the container from. As the level of oil rises, the float goes up, and the oil travels faster through the output pipe. The client wanted me to show this visually,so I used particles in the shape of arrows indicating the speed of oil travelling out of the pipe. So the arrow particles need to gain speed until the oil level reaches its top point,and then drop speed as it lowers. It is a bit of a long winded explanation,sorry!
I have tried using autokey and then changing the speed operator, but it doesn't seem to make a noticeable difference..so I am a bit stuck.

[katherinepyra]

I tried some of your suggestions, and worked something out that is to my liking...Thanks a bunch!

[BenBisares]

Glad to hear that they helped. If you have any follow-up questions don't hestiate to ask.

[jdong04]

Can you explain how you did this type of particle animation, I have a similar situation where a container is filled up with yogurt and then empties as the rotators spin. I can't seem to find too many tutorials on 3ds max particles that would help me in this particular situation, any advice would be greatly appreciated. 🙂

[katherinepyra]

I actually just turned on 'autokey' and changed my speed operator value. For some reason, the first time I tried it, it didnt work, and I was like 'oh well,must not be right'. But upon trying it again, it worked..I started by turning on autokeying, adding a key manually at the beginning, and then moving to the frame I wanted the particle's speed to be at the maximum, went and changed the value in the particle system's speed operator. This makes a key for you, and from there you can just go on changing the speed operator at the frame you want it to slow down or speed up at.