Using Fluid Simulations with Render Farms
How to use fluid simulations, like Mantaflow, with Renderjuice, the Blender render farm.
Status: ✅ Fully Supported
Fluid simulations, including those created with Mantaflow, are fully supported on Renderjuice and should work as expected out of the box 🎉 without much hassle.
Key Requirements: The key requirement is that you bake your fluid simulations and include the cache files when uploading your scene. Since fluid simulations rely on cache data that isn’t automatically embedded in the .blend
file, you must zip your fluid caches along with your scene before uploading.
If you’re seeing E:/
or similar in your cache path, you’ve not set the path correctly and it is still absolutely linked.
Here’s an incorrect and absolutely linked example:
Incorrect and absolutely linked cache path
Example Files
Below are example .blend
files demonstrating the correct and incorrect setups for fluid simulations.
Unbaked Example Incorrect ❌
Unbaked .blend
file with fluid simulation
Baked Example Correct ✅
Zipped .blend
file with baked fluid simulation cache
The examples feature a simple fluid simulation setup, showcasing how baking affects the simulation during rendering.
Instructions
To use fluid simulations with Renderjuice (and likely other render farms), you need to bake the simulation and include the cache files when uploading. The most common mistakes here
are forgetting to Save
after hitting Free All
and Bake All
or forgetting to make sure the cache paths are relative. In the case that your paths are incorrect,
we may either try to automatically fix them or your render might just miss the fluid simulation so be careful!
Set Up Your Fluid Simulation
Create your scene with the fluid simulation. This might involve setting up a domain, inflow objects, and configuring the simulation settings as desired.
Bake the Fluid Simulation
After setting up your simulation, you need to bake it.
To bake the fluid simulation:
- Select the domain object.
- Go to the Physics Properties panel.
- Under Fluid settings, navigate to the Settings section.
- Click on Bake All or Bake Data (depending on your Blender version). Or Free All in the case that you’ve already baked.
Physics Tab (1) Cache Path - note the `//` in the path. (2) Free All and Bake All Button (3) Bake Path Folder Icon
In this diagram we point out the following:
- the
//
is Blender’s way of saying “relative to the current file”, you may either type in your path here using//my-cache-folder-name
or use the folder icon to navigate to the cache location. If you have a drive likeC:\
orD:\
here you’ve not set the path correctly and it is still absolutely linked. - Click on Free All and Bake All to bake the simulation.
- You can use the folder icon to navigate to the cache location (which we elaborate on below).
Choose Cache Storage Location
By default, Blender will pick a random temporary directory for you if you haven’t saved your .blend
file yet which we don’t want!
- Verify the Cache Directory: In the Fluid settings under Cache, verify the Cache Directory path. It should be set to a folder that you can include when uploading.
- Ensure Cache Pathing is Correct: You should Free and Bake as needed so that the cache files are generated. Then make sure to save your
.blend
file. The last save ensures the pathing is persisted into the.blend
and the bake step writes the cache out to the disk.
You can do this by either:
- Typing in the path using
//my-cache-folder-name
- Using the GUI folder picker by pressing the folder icon (3 in the diagram above) to navigate to the cache location.
The name you set here does not matter, we only care that the path is relative.
When using the folder icon (via GUI), you should see something like this, note that you have to click on the Cog Icon to display the option to make the pathing relative.
When using the folder picker GUI, you *must* click on the Cog Icon to show the option for 'Relative Path'
Save Your Scene
After baking, make sure to save your .blend
file. The baked simulation references are now part of your scene.
Zip Your Scene and Cache
Zip your .blend
file along with the cache folder.
- Ensure the Cache Folder is Included: The cache folder typically has a name like
cache
blob
or similar and contains the baked simulation data.
Your zip file should have a structure similar to this, where your file is included in the zip
with your selected cache folder. Note that these extensions may vary from case to case.
Upload and Render
Upload your zipped file to Renderjuice and start your render.
Checklist
- Did you bake your fluid simulation?
- Did you save your
.blend
file after baking? - Did you include the cache folder when zipping your project?
- Is the cache directory path in Blender set correctly?
- Are all necessary objects included in the bake?
FAQ
Why do I need to bake fluid simulations?
Why do I need to bake fluid simulations?
Fluid simulations in Blender are not automatically included when rendering on a render farm. The simulation data is stored externally in cache files. Baking the simulation ensures that the fluid behavior is calculated and saved, and including the cache files ensures that the render farm can access this data to render your scene correctly.
Can I pack the fluid cache into the `.blend` file?
Can I pack the fluid cache into the `.blend` file?
No, Blender does not support packing fluid simulation caches into the .blend
file. You must include the cache files separately by zipping them along with your .blend
file.
How do I make sure the cache path is correct?
How do I make sure the cache path is correct?
In the Fluid settings under Cache, ensure the Cache Directory is set to a relative path. Ideally, it should be a folder next to your .blend
file. This way, when you zip the .blend
file and cache folder together, the simulation can find the cache files.
I'm seeing my simulation, but it's the old version!
I'm seeing my simulation, but it's the old version!
If you’re seeing your simulation, but it’s the old version, you’ve likely not saved your .blend
file after baking. Make sure to save your .blend
file after baking. As a reminder, baking writes the cache out to the disk, saving ensures your pathing is updated inside your .blend
file to point to the baked information you just made.
Do I need to bake other types of simulations?
Do I need to bake other types of simulations?
Yes, other simulations like smoke, fire, and particle systems also require baking and including their cache files when rendering on a render farm, but it’s usually the same process! We are looking into ways to make this a little easier in the future.
Can I use the 'Replay' cache type for fluid simulations?
Can I use the 'Replay' cache type for fluid simulations?
Sometimes, but it’s not recommended. Instead use the Modular or Final cache type rather than Replay. The Replay cache is intended for interactive playback in the viewport and more for iterating on the simulation in the viewport and not necessarily for final renders. The Replay option basically bakes for you as you work on your scene, but if you make changes and Blender hasn’t baked, then your changes won’t be persisted.
The Replay Cache Type
Having trouble or something doesn’t seem right? Just chat with us—we’re happy to help and respond quickly!