Two-Way Coupling with Fluent and Rocky: Applications in Water Treatment

Two-Way Coupling with Fluent and Rocky: Applications in Water Treatment Hello, today I would like to show how to create a model for Rocky-Fluent coupling. So I'll start with Fluent, so basically I have loaded my geometry which I created in DesignModeler.

Please note that I will be using ANSYS Fluent and Rocky. So basically, air is added here and we have three phases as you can see here, which are defined in the Eulerian tab, so the Eulerian dialog box.

So if you go into multi-phase, this is the key to actually making sure that your model works with Rocky as well. So you have to basically select the Eulerian model and make sure it's implicit. For the phases, I have basically three phases.

I have a phase containing water that I have defined as a mixture of water and some dissolved gases. Air, which is an air mixture containing oxygen, some nitrogen of course, and a little bit of CO 2. And the particles are defined here. Here I define a certain material for the particles.

I have here air as added as bubbles, mono-dispersed bubbles of 5mm each, water is my continuous primary phase, and that's basically it. Thank you for watching.

So basically, once we establish the model, we can go on into Rocky, but before I do that, I can advise you to run the model a bit to make sure it's working well, so I've done that already, and you can see here in the volume fraction for air, we can see how air is getting injected into the domain.

The main point here is the evolution of ANSYS software. The water is blue, the air is red, and the air is interacting with the water. To initialize, I had to first go into solutions and then patch. I have regions here for air and water. The region for water is defined by the cell zone.

I selected a region in my domain. My domain goes from 0 to 0.2 meters, the model bar texts data traces of the velocity profile is also a part of the ANSYS software. I've added other physics to it, but we're not really looking at that for now, such as mass transfer between gases from gas to liquid.

Let's look at the velocity profile. You can see the velocity profile here for the water phase, as well as for the air.

For now, you see that I have this phase called Particles here, which I'm not really using at this point, it's only defined, and this is where Rocky comes in, Rocky will link this phase, and this will become my DEM phase in Rocky. But I do have to have that phase reserved for Rocky.

So moving over to Rocky, here is the simulation that I loaded already from Fluent using the two-way coupling. So to do that, first thing is you go into study and there will be an option to enable CFD coupling and I enabled two-way coupling with Fluent.

So this will show up in Fluent and then this is where you can basically couple your simulation with Fluent. To do that, you also have to prepare the environment here in Rocky, so you have to define your particles, your DEM particles.

Here I define particles with a size of 1 mm, the same as what I have in Fluent for my particle phase. And you can define other properties like movement, composition, as well as things like the density of the particle, for example, and so on. So basically, this is what we have.

You also have to define where the particles are going to come in. Here I defined an inlet at the outlet boundary, so the outlet is for gas, but I defined that as my inlet for the particles to drop into the domain so they can reach the water level and basically interact with the aeration.

So basically, I've defined a mass flow rate of 0.04 tons per hour, and that happens for a period of one second as shown here. Starts at 0, goes all the way to 1 second, and I'm running the whole model for 3 seconds just for demonstration purposes.

So basically, this is where we load the particles, this is where we load the inlet for the particles. We also have to, after enabling CFD coupling, we have to enable interactions for the particles.

The fraction value is defined as 0.7, and then for zones and interfaces, I just clicked on the fluid, which is my domain basically in Fluent, and then this is where you actually load your case file from Fluent, so you can basically check this, click on load, and then locate your file, and then once you click on use data initialization, add your data file as well.

So that is basically the summary of how to set it up. I also put the additional arguments of this one. Basically, this is to make sure that the GUI doesn't pop up when you start running your simulation, which makes running things faster.

So your Fluent won't show up, you can still track its progress. Here you can choose a network interface, which offers some configuration and referencing options. And here we have how the particles work using ANSYS tools.

The evolution of particles dropping, so they have a fairly high velocity in the gas phase, but they drop significantly once they encounter the water surface. And then they are allowed to mix. You can see the arrows here are for the fluid phase.

If I approach a little bit, you can see arrows that are for the gas water phase, and the particles are basically the dots of different colors, colored by the translation velocity. Something I should mention also is the modules.

There are a number of different modules that you can add to keep track of certain physics, certain parameters. Please contact us at https://ozeninc.com/contact for more information.