Creating liquid flow with the help of RealFlow

VFX artist Vikrant Dalal reveals the top tools and techniques for using RealFlow to create liquid effects...

Hello everyone, I'm back again with a new tutorial that will help you to create liquid flow using RealFlow software. As with my previous tutorial, we'll be making with the minimum parameters, so get ready for one more exciting tutorial!

You might have seen this kind of effect in TV commercials, as they are often used to enhance the look of a product or shot. There are a number of software that can give this type of liquid effect, for example, Naiad, RealFlow and Houdini, but in this tutorial I'll show you how I created this effect with the help of RealFlow.

I can't teach you each and every parameter of this software, as this software is very vast and needs a lot of time to go through. So as far as the liquid flow is concerned we will learn as much as required for this particular tutorial only.

So get ready for this exciting tutorial!

The liquid flow effect we'll be creating using RealFlow

Create a new project

As we have seen in a lot of software, first we work on a file and then we save it in our specific folder with specific name. But in this software we can create the folder first and allocate the proper name of the file before working on it.

So let's create a file and folder. First, start the RealFlow application and you will see the Project management window – this is where you can set the file name and specific folder. Go to the Project Name tab and type the file name as appropriate and then move ahead to location, where you have to follow the path of specific folder, to determine where you want to save the file.

For example:
• File Name: Liquid Flow
• Location: D:/Tutorial
• Full Path: D:/Tutorial/Liquid Flow/Liquid Flow.flw

Now Hit the CREATE A NEW PROJECT button, and you can see that our file is ready to go.

This is the startup Project management window

This is the startup Project management window

Scene scale

Now we have to change the Scene Scale of our project file, because if we kept it default (which is 10) then it will take a lot of time to simulate. So let's reduce this amount. First go to Scale Option and change the Geometry Scale from
10 to 1.

Setting the scale options

Setting the scale options

Export Central

Export Central is an option to export everything you want from RealFlow. Within Export Central you can specify almost everything regarding location, naming and attributes of your simulation data. By simply activating and deactivating export options you can decide what you want to export, e.g. RealFlow Particles or RealFlow Mesh or Objects and so on.

To open Export Central got to Menu Bar > Export > Export Central, or simply press F12 on your keyboard. New nodes are automatically activated in Export Central when you create new project, but it's still important to open the window and go through that. The most important thing we want to export is RealFlow Mesh. After you open the window you can see the Particle Mesh option, but there is no Tick Mark option – don't worry, you will get this Tick Mark option after you create the Particle Mesh in our file. So don't forget to check this option before you hit the simulation button.

Working with the Export Central window

Working with the Export Central window

Emitters

We need to create three emitters to generate particles, and for that we will use circle emitters.
So go to Show Particle Fluid Menu > Circle and create three circle emitters. Use the following co-ordinates:

1. Circle 1
• Position – X:0.08034 | Y: 0.0 | Z: 3.58911
• Rotation – X:0.0 | Y: -102.5462 | Z:0.0
• Scale – X:0.5 | Y:0.5 | Z:0.5

2. Circle 2
• Position – X: -0.36873 | Y: -0.24856 | Z: 4.53896
• Rotation – X:0.0 | Y: -90.07204 | Z:0.0
• Scale – X:0.5 | Y:0.5 | Z:0.5

3. Circle 3
• Position – X: -0.20424 | Y: 0.14289 | Z: 4.04042
• Rotation – X:0.0 | Y: -81.90521 | Z:0.0
• Scale – X:0.5 | Y:0.5 | Z:0.5

Placing the circle emitters

Placing the circle emitters

Modify the parameters of emitters

Here, we have to change the parameters of our emitters. We will not change all the emitters, just modify the first emitter and then copy all the parameters and paste them in to the other two emitters.
To modify the parameters, select the emitter and go to Node Params, which should be on the right-side of the screen. Apply these to each of the three emitters:

• Type - Liquid
• Resolution - 20
• Density - 1000
• Int Pressure - 1.0
• Ext Pressure - 10.0
• Viscosity - 5.0
• Surface Tension - 100
• Interpolation - None
• Compute Vorticity - No
• Max Particles - 5000000

Tip: If you increase the resolution, you will get detail and hi-res simulation, but it will also increase the simulation time.

Changing the parameters of emitters

Changing the parameters of emitters

Noise Field Daemon

This Daemon can be used to randomly disturb particles or objects, which is particularly useful for simulating air turbulences.

To create this Daemon, go to Daemon Menu > Noise Field, and place this Daemon exactly on the emitters.

Noise Field
• Position – X: 0.0 | Y: 0.0 | Z: 3.9376
Parameters
• Affect - Force
• Strength - 60.0
• Scale Factor - 5.0
• Bounded - No

Applying Noise Field Daemon and modifying the parameters

Applying Noise Field Daemon and modifying the parameters

The Wind Daemon

To create this Daemon, go to Daemon Menu > Wind, then place it near the emitters in the co-ordinates as below.

Wind
• Position – X: -3.2396 | Y: 0.0 | Z: 4.43852
• Rotation - X: 0.0 | Y: -130.0* | Z: 0.0

* We are going to animate the Rotation of this wind in the Y axis. Go to Frame 0 and set the Rotation to 130. Now click the right-button of the mouse and select Add Key. Then go to Frame 20 and set the Rotation to 50 and select the Add Key. At Frame 40, set the Rotation to 130 and select Add Key.

After this, click the right-button on the mouse and select Open Curve. Here you can see the three key frames. Select Key Frame 40 and go to the Keys option in the Menu Bar and select Show Key Properties. Now set the Post Behavior to Loop Offset. After these changes you can see that we don't need to animate this wind manually until the last frame – it's automatically animated after frame 40.
Now let's modify the parameters of the wind.

Parameters
• Affect - Force
• Strength - 4.0
• Noise Strength - 25.0
• Noise Scale - 2.0
• Bounded - No

Adding the Wind Daemon and modifying the parameters

Adding the Wind Daemon and modifying the parameters

The Vortex Daemon

With a Vortex Daemon you're able to create a center of rotation around a certain point in space. To create this Daemon, go to Daemon Menu > Vortex, then place this Daemon exactly on the emitters.

• Position – X: -0.09342 | Y: 0.0 | Z: 3.91978
• Rotation - X: 0.0 | Y: 77.47419 | Z: 0.0

Now let's modify the parameters:
• Affect - Force
• Rot Strength - 2.5
• Central Strength - 20.0
• Attenuation - Linear
• Bounded - No
• Vortex Type - Classic
• Bound Sup - 1.0
• Bound Inf - 1.0

Adding the Vortex Daemon and modifying the parameters

Adding the Vortex Daemon and modifying the parameters

K-Volume Daemon
This Daemon eliminates unwanted particles from the scene. There are many cases where particles become invisible in the final camera view or leave a certain area. In most cases these particles only increase the simulation time without any additional benefit for the project. It's a real necessity to remove all these kinds of unwanted particles and K-Volume Daemon does this very accurately.

To create this Daemon, go to Daemon Menu > K Volume, and then place it near the emitters.

K-Volume Parameters
There is no need to place this Daemon manually. Just select it and go to Node Params – here you will see two options: Fit to Object and Fit to Scene. If you select the Fit to Object option then it will automatically adjust its scale as per the object size, or if you select Fit to Scene then it will adjust as per the scene size.

Adding the K-Volume Daemon

Adding the K-Volume Daemon

Simulation

After we finish the setups of the Emitters and Daemons, now it's time to hit the Simulation button.

The Simulation button

The Simulation button

RealFlow meshing

After you finish the simulation, it's time to create the mesh for our particles. To create the mesh, go to Mesh Menu > Particle Mesh (Standard). Now you can see that the ParticleMesh_ST01 node still appears in the Nodes section. Just right-click with the mouse and select Insert all Emitters. Now you can see the + sign near the ParticleMesh Node. This means all emitters have been inserted into this node.
Now select the Particle Mesh and go to Node Params and make the changes mentioned below:

Mesh
• Build - Yes
• Type - Metaballs
• Polygon Size - 0.01713
• LOD Resolution - No

Now click on that + sign, select the first emitter and go to Node Params and make these changes below:

Field
• Blend Factor - 95.0
• Radius - 0.012
• Subtractive Field - No

Now copy all the parameters and paste them into the other emitters. Select the Particle Mesh node, then go to Menu Bar and hit the Build Meshes button and wait till the process is finished.

Creating the RealFlow mesh for our particles

Creating the RealFlow mesh for our particles

The final output

After you finish the simulation and meshing, import the mesh into a 3D application, whichever is suitable for you. Just add some lights then render it and let's see how it looks.

Liquid flow in action

Related links

Check out Vikrant's studio website
Vikrant also has a YouTube page
Download assets to accompany this tutorial

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