Fluids

Create a plume of CO2 in an air stream

• peteroznewman
Subscriber

My curiosity got me to open Fluent and try something new. My experience with Fluent has been with single fluids: turbulent air flow over a wing and laminar water flow in a pipe from the edX course.

A discussion this week asked about a plume of CO2 and Raef's tutorial on Species transport hooked me to try to build what I hoped to be a simple model with two fluids that could mix together.

What I have so far is a Steady State, 2D planar domain with an air inlet velocity of 1 m/s on the left and a pressure outlet on the right plus a symmetry boundary at the top and bottom. I created a Named Selection called plumeinlet on a small square where I  have a CO2 inlet of 0.1 m/s.  Below is the velocity contour showing the square where the CO2 is coming out, which seems to be acting as a wall and casts a velocity shadow behind it.

Here is a snapshot of the Setup.

Here is the Species details.

In Raef's tutorial, he says to check Reactions, Volumetric, but  don't expect any reaction between air and CO2, as it is an inert-mixture so I leave it unchecked.

When I go to edit the Boundary Conditions, the Species Tab is not available to use until I change the Cell Zone Conditions to have inert-mixture replace air for the domain, then the Species tab is available in the Boundary Conditions window. On the inlet at the left edge, the co2 mass fraction is 0, which means pure air.

Here is the plot of CO2 mass fraction for air velocity of 1 m/s and CO2 velocity of 0.1 m/s

If I increase the velocity of CO2 3 times from the plumeinlet, then the contour of CO2 is shown below.

Below is the plot of CO2 mass fraction for air velocity of 0.2 m/s CO2 velocity of 0.3 m/s

If anyone has comments, I would like to hear them.

Regards,

Peter

• Rob
Ansys Employee

Looks fine from the plots.  As a more general comment the most common species (highest concentration overall) should be last in the list of species in the mixture as Fluent solves for n-1 species, whatever isn't accounted for is then species n.  In the species mixture properties you also want to think about the properties, can you use a constant or do you need to consider the mixture effects: in this example I'd use a mixture density and turn on gravity for 3d.

• vkt1990
Subscriber

I also want to design a 2D model just like peteroznewman  .
but I am not able to do that as I am new on ANSYS. it's my request to you kindly provide me a video link for such type of designs.that will be very helpful for me

• Rob
Ansys Employee

There are some species examples on YouTube and probably in the tutorials section on here, you'll need to adjust to suit your configuration.  For 2d in Fluent, set Workbench to 2d and build the model on the z=0 plane.

• Raef.Kobeissi
Subscriber

One of my favourite species transport simulations is this one:

• vkt1990
Subscriber

thank you Raef.Kobeissi  .

• peteroznewman
Subscriber

The original discussion showed a transient plume, so I wanted to run my first transient simulation and made the following video.