Fluid Sim - how to increase outflow?

[revolt_randy]

Hi all!

I’m using the fluid sim to create a small creek/stream. Here’s a screenshot of what I working with

The wireframe cube in the upper right corner is the inflow object. The other solid cube, which can barely be seen in the middle bottom, is the outflow object. Currently, the outflow object is less than the inflow object and as the sim runs, the water level rises. I need to increase the outflow to regulate the water level and I’m not seeing a place to control that. But I am new to the fluid sim.

WC_1058-1.blend (1.2 MB)

Thanks for any help!

Randy

[Zebrahead]

Hi Randy,
i think the problem is, that the fluid is slowly piling up back where the inflow is. If you change the size of the domain, so that it’s overlapping a bit with the inflow, the fluid can only flow along the river. Everything beyond the domain is out of scope of the simulation / will be deleted:

Edit: Haven’t read the post carefully enough if you want to increase the outflow, simply scale up the outflow object.

[revolt_randy]

Thanks @Zebrahead for your advice.

I think your advice works, but I’m not sure. I think my approach here is wrong. I want a small stream in an outdoor nature scene.

With an 8m cube as outflow and a 2m cube as inflow, over the course of 1000 frames, the level of the stream rises. Like it’s still not draining faster than filling. So maybe I should shut off the outflow until the stream fills to the desired level, then turn on the outflow.

Guess I will be working on a sink with a faucet and drain to figure it out.

Thanks,
Randy

[Zebrahead]

Hmmm, maybe the canal just can’t handle the amount of fluid

What i find interesting is, that it seams that there is no option to control the amount of fluid that is coming from the volume of the inflow object

You can however control the surface emission! Therefore, i would probably use a plane instead and adjust the surface emission to control the inflow:

It looks like as if the level is constant at around 800 frames then

[Blender_Fun1 (Blender.Fun)]

AFAIK you can kind of control the amount of fluid by

• the size of the inflow
• the velocity of the inflow

so here i made your inflow planar and some starting velocity, hopefully it helps.

WC_1058-1_rep.blend (1.1 MB)

[revolt_randy]

Had some time to play with the fluid sim, and I found a good video on the subject as well.

I ran a couple of tests with just 3 cubes, a domain, an inflow, and an outflow. With the inflow and outflow cubes at the same size, after 1000 frames I got this

The water level is at the bottom of the outflow cube (which can’t be seen here) and all the blue/green stuff is the splashing above the water level.

Scaled up the inflow cube 2x and I got this at 1000 frames -

Now you can see the outflow cube because it’s mostly below the water level.

Se yes @Zebrahead & @Blender_Fun1 you can control the infow by the scale of the inflow object. And likewise, you control the outflow -

@Zebrahead

if you want to increase the outflow, simply scale up the outflow object.

This video was very useful, at the 6:00 minute mark, it explains scaling up the inflow object to increase fluid amount. The whole video is worth watching, but I quit when it moved to materials and rendering.

And yes to this -

@Zebrahead

maybe the canal just can’t handle the amount of fluid

The canal can’t handle the fluid and I didn’t notice that. It gets a bit narrow right before the bend and the fluid backs up there before flowing to the rest of the stream.

On the right is the inflow, and on the left is the outflow, notice how the level is higher on the right? That’s because of the narrow section and the fluid backing up.

So here’s what I’m going to do. As I mentioned before, I’m going to turn off the outflow and allow the area to fill with fluid. Once the water level is even, then turn on the outflow object. Position of the outflow object should be raised to the level of the water also.

Of course, I should also model a better canal…

Thanks for the help,
Randy